Expressions (mongodb-async-driver 2.0.1 API)

java.lang.Object
- com.allanbank.mongodb.builder.expression.Expressions

```
public final class Expressions
extends Object
```
Expressions provides a collection of static helper method for constructing complex expression.

API Notice:

This class is part of the driver's API. Public and protected members will be deprecated for at least 1 non-bugfix release (version numbers are <major>.<minor>.<bugfix>) before being removed or modified.

Copyright ©:

2012-2013, Allanbank Consulting, Inc., All Rights Reserved

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`ADD` The "$add" operator token
`static String`	`ALL_ELEMENTS_TRUE` The "$allElementsTrue" operator token
`static String`	`AND` The "$and" operator token
`static String`	`ANY_ELEMENT_TRUE` The "$anyElementTrue" operator token
`static String`	`COMPARE` The "$cmp" operator token
`static String`	`CONCATENATE` The "$concat" operator token
`static String`	`CONDITION` The "$cond" operator token
`static String`	`DAY_OF_MONTH` The "$dayOfMonth" operator token
`static String`	`DAY_OF_WEEK` The "$dayOfWeek" operator token
`static String`	`DAY_OF_YEAR` The "$dayOfYear" operator token
`static String`	`DIVIDE` The "$divide" operator token
`static String`	`EQUAL` The "$eq" operator token
`static String`	`GREATER_THAN` The "$gt" operator token
`static String`	`GREATER_THAN_OR_EQUAL` The "$gte" operator token
`static String`	`HOUR` The "$hour" operator token
`static String`	`IF_NULL` The "$ifNull" operator token
`static String`	`LESS_THAN` The "$lt" operator token
`static String`	`LESS_THAN_OR_EQUAL` The "$lte" operator token
`static String`	`LITERAL` The "$literal" operator token
`static String`	`MILLISECOND` The "$millisecond" operator token
`static String`	`MINUTE` The "$minute" operator token
`static String`	`MODULO` The "$mod" operator token
`static String`	`MONTH` The "$month" operator token
`static String`	`MULTIPLY` The "$multiply" operator token
`static String`	`NOT` The "$not" operator token
`static String`	`NOT_EQUAL` The "$ne" operator token
`static String`	`OR` The "$or" operator token
`static String`	`SECOND` The "$second" operator token
`static String`	`SET_DIFFERENCE` The "$setDifference" operator token
`static String`	`SET_EQUALS` The "$setEquals" operator token
`static String`	`SET_INTERSECTION` The "$setIntersection" operator token
`static String`	`SET_IS_SUBSET` The "$setIsSubset" operator token
`static String`	`SET_UNION` The "$setUnion" operator token
`static String`	`SIZE` The "$size" operator token
`static String`	`STRING_CASE_INSENSITIVE_COMPARE` The "$strcasecmp" operator token
`static String`	`SUB_STRING` The "$substr" operator token
`static String`	`SUBTRACT` The "$subtract" operator token
`static String`	`TO_LOWER` The "$toLower" operator token
`static String`	`TO_UPPER` The "$toUpper" operator token
`static String`	`WEEK` The "$week" operator token
`static String`	`YEAR` The "$year" operator token

Method Summary

Methods
Modifier and Type	Method and Description
`static NaryExpression`	`add(Expression... expressions)` Returns an `NaryExpression` "$add" expression.
`static UnaryExpression`	`allElementsTrue(Expression expression)` Returns a `UnaryExpression` "$allElementsTrue" expression.
`static NaryExpression`	`and(Expression... expressions)` Returns an `NaryExpression` "$and" expression.
`static UnaryExpression`	`anyElementTrue(Expression expression)` Returns a `UnaryExpression` "$anyElementTrue" expression.
`static NaryExpression`	`cmp(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$cmp" expression.
`static NaryExpression`	`concatenate(Expression... expression)` Returns a `NaryExpression` "$concat" expression.
`static NaryExpression`	`cond(Expression test, Expression trueResult, Expression falseResult)` Returns a `NaryExpression` "$cond" expression.
`static Constant`	`constant(boolean value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constant(Date value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constant(double value)` Returns a `Constant` expression with the provided `value`.
`static Expression`	`constant(Element element)` Returns a `Constant` expression wrapping the provided `element`.
`static Constant`	`constant(int value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constant(long value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constant(ObjectId value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constant(Pattern value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constant(String value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constantMongoTimestamp(long value)` Returns a `Constant` expression with the provided `value`.
`static Constant`	`constantTimestamp(long value)` Returns a `Constant` expression with the provided `value`.
`static UnaryExpression`	`dayOfMonth(Expression expression)` Returns a `UnaryExpression` "$dayOfMonth" expression.
`static UnaryExpression`	`dayOfWeek(Expression expression)` Returns a `UnaryExpression` "$dayOfWeek" expression.
`static UnaryExpression`	`dayOfYear(Expression expression)` Returns a `UnaryExpression` "$dayOfYear" expression.
`static NaryExpression`	`divide(Expression numerator, Expression denominator)` Returns a `NaryExpression` "$divide" expression.
`static NaryExpression`	`eq(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$eq" expression.
`static Constant`	`field(String fieldName)` Returns a `Constant` expression with the provided `fieldName`.
`static NaryExpression`	`gt(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$gt" expression.
`static NaryExpression`	`gte(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$gte" expression.
`static UnaryExpression`	`hour(Expression expression)` Returns a `UnaryExpression` "$hour" expression.
`static NaryExpression`	`ifNull(Expression first, Expression second)` Returns a `NaryExpression` "$ifNull" expression.
`static UnaryExpression`	`let(Expression inExpression, Element... variables)` Creates a `$let` expression with the provided variables and `in` expression.
`static UnaryExpression`	`let(List<Element> variables, Expression inExpression)` Creates a `$let` expression with the provided variables and `in` expression.
`static LetBuilder`	`let(String name, DocumentAssignable document)` Starts the creation of a `$let` expression.
`static LetBuilder`	`let(String name, Expression expression)` Starts the creation of a `$let` expression.
`static Constant`	`literal(String value)` Returns a `Constant` expression wrapping the `value` in a "$literal" sub-document.
`static NaryExpression`	`lt(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$lt" expression.
`static NaryExpression`	`lte(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$lte" expression.
`static MapStage1`	`map(String inputField)` Returns a `UnaryExpression` expression for the `$map` operation.
`static UnaryExpression`	`map(String inputField, String variableName, Expression mapOperation)` Returns a `UnaryExpression` expression for the `$map` operation.
`static UnaryExpression`	`millisecond(Expression expression)` Returns a `UnaryExpression` "$millisecond" expression.
`static UnaryExpression`	`minute(Expression expression)` Returns a `UnaryExpression` "$minute" expression.
`static NaryExpression`	`mod(Expression numerator, Expression denominator)` Returns a `NaryExpression` "$mod" expression.
`static UnaryExpression`	`month(Expression expression)` Returns a `UnaryExpression` "$month" expression.
`static NaryExpression`	`multiply(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$multiply" expression.
`static NaryExpression`	`ne(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$ne" expression.
`static UnaryExpression`	`not(Expression expression)` Returns a `UnaryExpression` "$not" expression.
`static Constant`	`nullConstant()` Returns a `null` `Constant` expression.
`static NaryExpression`	`or(Expression... expressions)` Returns an `NaryExpression` "$or" expression.
`static UnaryExpression`	`second(Expression expression)` Returns a `UnaryExpression` "$second" expression.
`static Element`	`set(String name, DocumentAssignable document)` Returns an element to set the value to.
`static Element`	`set(String name, Expression expression)` Returns an element to set the value to.
`static NaryExpression`	`setDifference(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$setDifference" expression.
`static NaryExpression`	`setEquals(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$setEquals" expression.
`static NaryExpression`	`setIntersection(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$setIntersection" expression.
`static NaryExpression`	`setIsSubset(Expression subSet, Expression completeSet)` Returns a `NaryExpression` "$setIsSubset" expression.
`static NaryExpression`	`setUnion(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$setUnion" expression.
`static UnaryExpression`	`size(Expression expression)` Returns a `UnaryExpression` "$size" expression.
`static NaryExpression`	`strcasecmp(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$strcasecmp" expression.
`static NaryExpression`	`substr(Expression string, Expression skip, Expression length)` Returns a `NaryExpression` "$substr" expression.
`static NaryExpression`	`subtract(Expression lhs, Expression rhs)` Returns a `NaryExpression` "$subtract" expression.
`static UnaryExpression`	`toLower(Expression string)` Returns a `UnaryExpression` "$toLower" expression.
`static UnaryExpression`	`toUpper(Expression string)` Returns a `UnaryExpression` "$toUpper" expression.
`static Constant`	`var(String variableName)` Returns a `Constant` expression with the provided `variableName`.
`static UnaryExpression`	`week(Expression expression)` Returns a `UnaryExpression` "$week" expression.
`static UnaryExpression`	`year(Expression expression)` Returns a `UnaryExpression` "$year" expression.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- ADD
```
public static final String ADD
```
  The "$add" operator token
  
  See Also:
  Constant Field Values
- ALL_ELEMENTS_TRUE
```
public static final String ALL_ELEMENTS_TRUE
```
  The "$allElementsTrue" operator token
  
  See Also:
  Constant Field Values
- AND
```
public static final String AND
```
  The "$and" operator token
  
  See Also:
  Constant Field Values
- ANY_ELEMENT_TRUE
```
public static final String ANY_ELEMENT_TRUE
```
  The "$anyElementTrue" operator token
  
  See Also:
  Constant Field Values
- COMPARE
```
public static final String COMPARE
```
  The "$cmp" operator token
  
  See Also:
  Constant Field Values
- CONCATENATE
```
public static final String CONCATENATE
```
  The "$concat" operator token
  
  See Also:
  Constant Field Values
- CONDITION
```
public static final String CONDITION
```
  The "$cond" operator token
  
  See Also:
  Constant Field Values
- DAY_OF_MONTH
```
public static final String DAY_OF_MONTH
```
  The "$dayOfMonth" operator token
  
  See Also:
  Constant Field Values
- DAY_OF_WEEK
```
public static final String DAY_OF_WEEK
```
  The "$dayOfWeek" operator token
  
  See Also:
  Constant Field Values
- DAY_OF_YEAR
```
public static final String DAY_OF_YEAR
```
  The "$dayOfYear" operator token
  
  See Also:
  Constant Field Values
- DIVIDE
```
public static final String DIVIDE
```
  The "$divide" operator token
  
  See Also:
  Constant Field Values
- EQUAL
```
public static final String EQUAL
```
  The "$eq" operator token
  
  See Also:
  Constant Field Values
- GREATER_THAN
```
public static final String GREATER_THAN
```
  The "$gt" operator token
  
  See Also:
  Constant Field Values
- GREATER_THAN_OR_EQUAL
```
public static final String GREATER_THAN_OR_EQUAL
```
  The "$gte" operator token
  
  See Also:
  Constant Field Values
- HOUR
```
public static final String HOUR
```
  The "$hour" operator token
  
  See Also:
  Constant Field Values
- IF_NULL
```
public static final String IF_NULL
```
  The "$ifNull" operator token
  
  See Also:
  Constant Field Values
- LESS_THAN
```
public static final String LESS_THAN
```
  The "$lt" operator token
  
  See Also:
  Constant Field Values
- LESS_THAN_OR_EQUAL
```
public static final String LESS_THAN_OR_EQUAL
```
  The "$lte" operator token
  
  See Also:
  Constant Field Values
- LITERAL
```
public static final String LITERAL
```
  The "$literal" operator token
  
  See Also:
  Constant Field Values
- MILLISECOND
```
public static final String MILLISECOND
```
  The "$millisecond" operator token
  
  See Also:
  Constant Field Values
- MINUTE
```
public static final String MINUTE
```
  The "$minute" operator token
  
  See Also:
  Constant Field Values
- MODULO
```
public static final String MODULO
```
  The "$mod" operator token
  
  See Also:
  Constant Field Values
- MONTH
```
public static final String MONTH
```
  The "$month" operator token
  
  See Also:
  Constant Field Values
- MULTIPLY
```
public static final String MULTIPLY
```
  The "$multiply" operator token
  
  See Also:
  Constant Field Values
- NOT
```
public static final String NOT
```
  The "$not" operator token
  
  See Also:
  Constant Field Values
- NOT_EQUAL
```
public static final String NOT_EQUAL
```
  The "$ne" operator token
  
  See Also:
  Constant Field Values
- OR
```
public static final String OR
```
  The "$or" operator token
  
  See Also:
  Constant Field Values
- SECOND
```
public static final String SECOND
```
  The "$second" operator token
  
  See Also:
  Constant Field Values
- SET_DIFFERENCE
```
public static final String SET_DIFFERENCE
```
  The "$setDifference" operator token
  
  See Also:
  Constant Field Values
- SET_EQUALS
```
public static final String SET_EQUALS
```
  The "$setEquals" operator token
  
  See Also:
  Constant Field Values
- SET_INTERSECTION
```
public static final String SET_INTERSECTION
```
  The "$setIntersection" operator token
  
  See Also:
  Constant Field Values
- SET_IS_SUBSET
```
public static final String SET_IS_SUBSET
```
  The "$setIsSubset" operator token
  
  See Also:
  Constant Field Values
- SET_UNION
```
public static final String SET_UNION
```
  The "$setUnion" operator token
  
  See Also:
  Constant Field Values
- SIZE
```
public static final String SIZE
```
  The "$size" operator token
  
  See Also:
  Constant Field Values
- STRING_CASE_INSENSITIVE_COMPARE
```
public static final String STRING_CASE_INSENSITIVE_COMPARE
```
  The "$strcasecmp" operator token
  
  See Also:
  Constant Field Values
- SUB_STRING
```
public static final String SUB_STRING
```
  The "$substr" operator token
  
  See Also:
  Constant Field Values
- SUBTRACT
```
public static final String SUBTRACT
```
  The "$subtract" operator token
  
  See Also:
  Constant Field Values
- TO_LOWER
```
public static final String TO_LOWER
```
  The "$toLower" operator token
  
  See Also:
  Constant Field Values
- TO_UPPER
```
public static final String TO_UPPER
```
  The "$toUpper" operator token
  
  See Also:
  Constant Field Values
- WEEK
```
public static final String WEEK
```
  The "$week" operator token
  
  See Also:
  Constant Field Values
- YEAR
```
public static final String YEAR
```
  The "$year" operator token
  
  See Also:
  Constant Field Values

Method Detail

add
```
public static NaryExpression add(Expression... expressions)
```
Returns an NaryExpression "$add" expression.

Parameters:
expressions - The sub-expressions.

Returns:
The NaryExpression "$add" expression.

allElementsTrue
```
public static UnaryExpression allElementsTrue(Expression expression)
```
Returns a UnaryExpression "$allElementsTrue" expression.

Parameters:
expression - The expression that will be evaluated to create the set to inspect for a true element.

Returns:
The UnaryExpression "$allElementsTrue" expression.

and
```
public static NaryExpression and(Expression... expressions)
```
Returns an NaryExpression "$and" expression.

Parameters:
expressions - The sub-expressions.

Returns:
The NaryExpression "$and" expression.

anyElementTrue
```
public static UnaryExpression anyElementTrue(Expression expression)
```
Returns a UnaryExpression "$anyElementTrue" expression.

Parameters:
expression - The expression that will be evaluated to create the set to inspect for a true element.

Returns:
The UnaryExpression "$anyElementTrue" expression.

cmp
```
public static NaryExpression cmp(Expression lhs,
                 Expression rhs)
```
Returns a NaryExpression "$cmp" expression.

Parameters:
lhs - The left hand side of the operation.
rhs - The left hand side of the operation.

Returns:
The NaryExpression "$cmp" expression.

concatenate
```
public static NaryExpression concatenate(Expression... expression)
```
Returns a NaryExpression "$concat" expression.

Parameters:
expression - The string expressions for the operator.

Returns:
The NaryExpression "$concat" expression.
Since:

MongoDB 2.4

cond
```
public static NaryExpression cond(Expression test,
                  Expression trueResult,
                  Expression falseResult)
```
Returns a NaryExpression "$cond" expression.

Parameters:
test - The conditions test.
trueResult - The result if the test is true.
falseResult - The result if the test is false.

Returns:
The NaryExpression "$cond" expression.

constant
```
public static Constant constant(boolean value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant
```
public static Constant constant(Date value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant
```
public static Constant constant(double value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant

public static Expression constant(Element element)

Returns a Constant expression wrapping the provided element. This method is intended mainly for wrapping arrays using the BuilderFactory.a() method.

 
 import static com.allanbank.mongodb.bson.builder.BuilderFactory.a
 import static com.allanbank.mongodb.builder.expression.Expressions.constant
 
 constant( a( "This", "is", "an", "array" ) );

Parameters:: element - The element value.
Returns:: The Constant expression.

constant
```
public static Constant constant(int value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant
```
public static Constant constant(long value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant
```
public static Constant constant(ObjectId value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant
```
public static Constant constant(Pattern value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constant
```
public static Constant constant(String value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constantMongoTimestamp
```
public static Constant constantMongoTimestamp(long value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

constantTimestamp
```
public static Constant constantTimestamp(long value)
```
Returns a Constant expression with the provided value.

Parameters:
value - The constants value.

Returns:
The Constant expression.

dayOfMonth
```
public static UnaryExpression dayOfMonth(Expression expression)
```
Returns a UnaryExpression "$dayOfMonth" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$dayOfMonth" expression.

dayOfWeek
```
public static UnaryExpression dayOfWeek(Expression expression)
```
Returns a UnaryExpression "$dayOfWeek" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$dayOfWeek" expression.

dayOfYear
```
public static UnaryExpression dayOfYear(Expression expression)
```
Returns a UnaryExpression "$dayOfYear" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$dayOfYear" expression.

divide
```
public static NaryExpression divide(Expression numerator,
                    Expression denominator)
```
Returns a NaryExpression "$divide" expression.

Parameters:
numerator - The numerator of the division.
denominator - The denominator of the division.

Returns:
The NaryExpression "$divide" expression.

eq
```
public static NaryExpression eq(Expression lhs,
                Expression rhs)
```
Returns a NaryExpression "$eq" expression.

Parameters:
lhs - The left hand side of the equals.
rhs - The right hand side of the equals.

Returns:
The NaryExpression "$eq" expression.

field
```
public static Constant field(String fieldName)
```
Returns a Constant expression with the provided fieldName.
Prepends a $ to the field name if not already present.
```
 
 Constant field = Expressions.field("field");
 
 // Produces output: 
 //      $field
 System.out.println(field);
 
 
```
Parameters:
fieldName - The name of the field.

Returns:
The Constant expression.

gt
```
public static NaryExpression gt(Expression lhs,
                Expression rhs)
```
Returns a NaryExpression "$gt" expression.

Parameters:
lhs - The left hand side of the comparison.
rhs - The right hand side of the comparison.

Returns:
The NaryExpression "$gt" expression.

gte
```
public static NaryExpression gte(Expression lhs,
                 Expression rhs)
```
Returns a NaryExpression "$gte" expression.

Parameters:
lhs - The left hand side of the comparison.
rhs - The right hand side of the comparison.

Returns:
The NaryExpression "$gte" expression.

hour
```
public static UnaryExpression hour(Expression expression)
```
Returns a UnaryExpression "$hour" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$hour" expression.

ifNull
```
public static NaryExpression ifNull(Expression first,
                    Expression second)
```
Returns a NaryExpression "$ifNull" expression.

Parameters:
first - The first expression.
second - The second expression.

Returns:
The NaryExpression "$ifNull" expression.

let

public static UnaryExpression let(Expression inExpression,
                  Element... variables)

Creates a $let expression with the provided variables and in expression.

Here is the let expression's documentation aggregation pipe line using this helper class.

 
 import static com.allanbank.mongodb.builder.AggregationProjectFields.include;
 import static com.allanbank.mongodb.builder.expression.Expressions.add;
 import static com.allanbank.mongodb.builder.expression.Expressions.cond;
 import static com.allanbank.mongodb.builder.expression.Expressions.constant;
 import static com.allanbank.mongodb.builder.expression.Expressions.field;
 import static com.allanbank.mongodb.builder.expression.Expressions.let;
 import static com.allanbank.mongodb.builder.expression.Expressions.multiply;
 import static com.allanbank.mongodb.builder.expression.Expressions.set;
 import static com.allanbank.mongodb.builder.expression.Expressions.var;
 
 Aggregate.Builder aggregate = Aggregate.builder();
 
 //   $project: {
 //      finalTotal: {
 //         $let: {
 //            vars: {
 //               total: { $add: [ '$price', '$tax' ] },
 //               discounted: { $cond: { if: '$applyDiscount', then: 0.9, else: 1 } }
 //            },
 //            in: { $multiply: [ "$$total", "$$discounted" ] }
 //         }
 //      }
 //   }
 final Aggregate.Builder aggregation = Aggregate.builder();
 aggregation.project(
         include(),
         set("finalTotal",
                 let(
                    multiply(var("total"), var("discounted"))
                    set("total", add(field("price"), field("tax"))),
                    set("discounted",
                         cond(field("applyDiscount"), constant(0.9),
                                 constant(1))))));
 
 // Aggregation Pipeline : '$pipeline' : [
 //   {
 //     '$project' : {
 //       finalTotal : {
 //         '$let' : {
 //           vars : {
 //             total : {
 //               '$add' : [
 //                 '$price', 
 //                 '$tax'
 //               ]
 //             },
 //             discounted : {
 //               '$cond' : [
 //                 '$applyDiscount', 
 //                 0.9, 
 //                 1
 //               ]
 //             }
 //           },
 //           in : {
 //             '$multiply' : [
 //               '$$total', 
 //               '$$discounted'
 //             ]
 //           }
 //         }
 //       }
 //     }
 //   }
 // ]
 System.out.println("Aggregation Pipeline : " + aggregation);

Parameters:: inExpression - The expression to be evaluated with the variables within the $let expression.; variables - The variables for the $let expression.
Returns:: The Element to set the value to the document.

let

public static UnaryExpression let(List<Element> variables,
                  Expression inExpression)

Creates a $let expression with the provided variables and in expression.

Here is the let expression's documentation aggregation pipe line using this helper class.

 
 import static com.allanbank.mongodb.builder.AggregationProjectFields.include;
 import static com.allanbank.mongodb.builder.expression.Expressions.add;
 import static com.allanbank.mongodb.builder.expression.Expressions.cond;
 import static com.allanbank.mongodb.builder.expression.Expressions.constant;
 import static com.allanbank.mongodb.builder.expression.Expressions.field;
 import static com.allanbank.mongodb.builder.expression.Expressions.let;
 import static com.allanbank.mongodb.builder.expression.Expressions.multiply;
 import static com.allanbank.mongodb.builder.expression.Expressions.set;
 import static com.allanbank.mongodb.builder.expression.Expressions.var;
 
 Aggregate.Builder aggregate = Aggregate.builder();
 
 //   $project: {
 //      finalTotal: {
 //         $let: {
 //            vars: {
 //               total: { $add: [ '$price', '$tax' ] },
 //               discounted: { $cond: { if: '$applyDiscount', then: 0.9, else: 1 } }
 //            },
 //            in: { $multiply: [ "$$total", "$$discounted" ] }
 //         }
 //      }
 //   }
 final Aggregate.Builder aggregation = Aggregate.builder();
 aggregation.project(
         include(),
         set("finalTotal",
                 let(
                    Arrays.asList(
                       set("total", add(field("price"), field("tax"))),
                       set("discounted",
                          cond(field("applyDiscount"), constant(0.9),
                                 constant(1))))
                    multiply(var("total"), var("discounted")))));
 
 // Aggregation Pipeline : '$pipeline' : [
 //   {
 //     '$project' : {
 //       finalTotal : {
 //         '$let' : {
 //           vars : {
 //             total : {
 //               '$add' : [
 //                 '$price', 
 //                 '$tax'
 //               ]
 //             },
 //             discounted : {
 //               '$cond' : [
 //                 '$applyDiscount', 
 //                 0.9, 
 //                 1
 //               ]
 //             }
 //           },
 //           in : {
 //             '$multiply' : [
 //               '$$total', 
 //               '$$discounted'
 //             ]
 //           }
 //         }
 //       }
 //     }
 //   }
 // ]
 System.out.println("Aggregation Pipeline : " + aggregation);

Parameters:: variables - The variables for the $let expression.; inExpression - The expression to be evaluated with the variables within the $let expression.
Returns:: The Element to set the value to the document.

let

public static LetBuilder let(String name,
             DocumentAssignable document)

Starts the creation of a $let expression. The returned LetBuilder can be used to add additional variables before setting the final expression to evaluate.

Here is the let expression's documentation aggregation pipe line using this helper class.

 
 import static com.allanbank.mongodb.builder.AggregationProjectFields.include;
 import static com.allanbank.mongodb.builder.expression.Expressions.add;
 import static com.allanbank.mongodb.builder.expression.Expressions.cond;
 import static com.allanbank.mongodb.builder.expression.Expressions.constant;
 import static com.allanbank.mongodb.builder.expression.Expressions.field;
 import static com.allanbank.mongodb.builder.expression.Expressions.let;
 import static com.allanbank.mongodb.builder.expression.Expressions.multiply;
 import static com.allanbank.mongodb.builder.expression.Expressions.set;
 import static com.allanbank.mongodb.builder.expression.Expressions.var;
 
 Aggregate.Builder aggregate = Aggregate.builder();
 
 //   $project: {
 //      finalTotal: {
 //         $let: {
 //            vars: {
 //               total: { $add: [ '$price', '$tax' ] },
 //               discounted: { $cond: { if: '$applyDiscount', then: 0.9, else: 1 } }
 //            },
 //            in: { $multiply: [ "$$total", "$$discounted" ] }
 //         }
 //      }
 //   }
 final Aggregate.Builder aggregation = Aggregate.builder();
 aggregation.project(
         include(),
         set("finalTotal",
                         let("total", add(field("price"), field("tax")))
                            .let("discounted", cond(field("applyDiscount"), 
                                                    constant(0.9),
                                                    constant(1)))
                            .in(multiply(var("total"), var("discounted")))));
 
 // Aggregation Pipeline : '$pipeline' : [
 //   {
 //     '$project' : {
 //       finalTotal : {
 //         '$let' : {
 //           vars : {
 //             total : {
 //               '$add' : [
 //                 '$price', 
 //                 '$tax'
 //               ]
 //             },
 //             discounted : {
 //               '$cond' : [
 //                 '$applyDiscount', 
 //                 0.9, 
 //                 1
 //               ]
 //             }
 //           },
 //           in : {
 //             '$multiply' : [
 //               '$$total', 
 //               '$$discounted'
 //             ]
 //           }
 //         }
 //       }
 //     }
 //   }
 // ]
 System.out.println("Aggregation Pipeline : " + aggregation);

Parameters:: name - The name of the first field to set.; document - The document to set the first field value to.
Returns:: The Element to set the value to the document.

let

public static LetBuilder let(String name,
             Expression expression)

Starts the creation of a $let expression. The returned LetBuilder can be used to add additional variables before setting the final expression to evaluate.

Here is the let expression's documentation aggregation pipe line using this helper class.

 
 import static com.allanbank.mongodb.builder.AggregationProjectFields.include;
 import static com.allanbank.mongodb.builder.expression.Expressions.add;
 import static com.allanbank.mongodb.builder.expression.Expressions.cond;
 import static com.allanbank.mongodb.builder.expression.Expressions.constant;
 import static com.allanbank.mongodb.builder.expression.Expressions.field;
 import static com.allanbank.mongodb.builder.expression.Expressions.let;
 import static com.allanbank.mongodb.builder.expression.Expressions.multiply;
 import static com.allanbank.mongodb.builder.expression.Expressions.set;
 import static com.allanbank.mongodb.builder.expression.Expressions.var;
 
 Aggregate.Builder aggregate = Aggregate.builder();
 
 //   $project: {
 //      finalTotal: {
 //         $let: {
 //            vars: {
 //               total: { $add: [ '$price', '$tax' ] },
 //               discounted: { $cond: { if: '$applyDiscount', then: 0.9, else: 1 } }
 //            },
 //            in: { $multiply: [ "$$total", "$$discounted" ] }
 //         }
 //      }
 //   }
 final Aggregate.Builder aggregation = Aggregate.builder();
 aggregation.project(
         include(),
         set("finalTotal",
                         let("total", add(field("price"), field("tax")))
                            .let("discounted", cond(field("applyDiscount"), 
                                                    constant(0.9),
                                                    constant(1)))
                            .in(multiply(var("total"), var("discounted")))));
 
 // Aggregation Pipeline : '$pipeline' : [
 //   {
 //     '$project' : {
 //       finalTotal : {
 //         '$let' : {
 //           vars : {
 //             total : {
 //               '$add' : [
 //                 '$price', 
 //                 '$tax'
 //               ]
 //             },
 //             discounted : {
 //               '$cond' : [
 //                 '$applyDiscount', 
 //                 0.9, 
 //                 1
 //               ]
 //             }
 //           },
 //           in : {
 //             '$multiply' : [
 //               '$$total', 
 //               '$$discounted'
 //             ]
 //           }
 //         }
 //       }
 //     }
 //   }
 // ]
 System.out.println("Aggregation Pipeline : " + aggregation);

Parameters:: name - The name of the field to set.; expression - The expression to compute the value for the first field.
Returns:: The Element to set the value to the expression.

literal
```
public static Constant literal(String value)
```
Returns a Constant expression wrapping the value in a "$literal" sub-document.

Parameters:
value - The constants value.

Returns:
The Constant expression.

lt
```
public static NaryExpression lt(Expression lhs,
                Expression rhs)
```
Returns a NaryExpression "$lt" expression.

Parameters:
lhs - The left hand side of the comparison.
rhs - The right hand side of the comparison.

Returns:
The NaryExpression "$lt" expression.

lte
```
public static NaryExpression lte(Expression lhs,
                 Expression rhs)
```
Returns a NaryExpression "$lte" expression.

Parameters:
lhs - The left hand side of the comparison.
rhs - The right hand side of the comparison.

Returns:
The NaryExpression "$lt" expression.

map

public static MapStage1 map(String inputField)

Returns a UnaryExpression expression for the $map operation.

Prepends a $ to the inputField name if not already present.

Here is the map expression's documentation aggregation pipe line using this helper class.

 
 import static com.allanbank.mongodb.builder.AggregationProjectFields.include;
 import static com.allanbank.mongodb.builder.expression.Expressions.map;
 import static com.allanbank.mongodb.builder.expression.Expressions.set;
 import static com.allanbank.mongodb.builder.expression.Expressions.add;
 import static com.allanbank.mongodb.builder.expression.Expressions.var;
 import static com.allanbank.mongodb.builder.expression.Expressions.constant;
 
 Aggregate.Builder aggregate = Aggregate.builder();
 
 // { $project: { adjustments: { $map: { input: "$skews",
 //                            as: "adj",
 //                            in: { $add: [ "$$adj", 12 ] } } } } }
 aggregate.project(
     include(),
     set( "adjustments", 
         map("skews").as("adj").in( add( var("adj"), constant(12) ) ) ) );
 
 // Produces output: 
 //    {
 //       '$project' : {
 //          adjustments : {
 //             '$map' {
 //                input : '$skews',
 //                as : 'adj',
 //                in : {
 //                   '$add' : [
 //                      '$$adj',
 //                      12
 //                   ]
 //                }
 //             }
 //          }
 //       }
 //    }
 System.out.println(aggregate);

Parameters:: inputField - The name of the input field. The map operation expression.
Returns:: The first stage of the $map expression construction.
See Also:: map expression documentation

map

public static UnaryExpression map(String inputField,
                  String variableName,
                  Expression mapOperation)

Returns a UnaryExpression expression for the $map operation.

Prepends a $ to the inputField name if not already present.

Here is the map expression's documentation aggregation pipe line using this helper class.

 
 import static com.allanbank.mongodb.builder.AggregationProjectFields.include;
 import static com.allanbank.mongodb.builder.expression.Expressions.map;
 import static com.allanbank.mongodb.builder.expression.Expressions.set;
 import static com.allanbank.mongodb.builder.expression.Expressions.add;
 import static com.allanbank.mongodb.builder.expression.Expressions.var;
 import static com.allanbank.mongodb.builder.expression.Expressions.constant;
 
 Aggregate.Builder aggregate = Aggregate.builder();
 
 // { $project: { adjustments: { $map: { input: "$skews",
 //                            as: "adj",
 //                            in: { $add: [ "$$adj", 12 ] } } } } }
 aggregate.project(
     include(),
     set( "adjustments", 
         map( "skews", "adj",
            add( var("adj"), constant(12) ) ) ) );
 
 // Produces output: 
 //    {
 //       '$project' : {
 //          adjustments : {
 //             '$map' {
 //                input : '$skews',
 //                as : 'adj',
 //                in : {
 //                   '$add' : [
 //                      '$$adj',
 //                      12
 //                   ]
 //                }
 //             }
 //          }
 //       }
 //    }
 System.out.println(aggregate);

Parameters:: inputField - The name of the input field.; variableName - The name of the as variable.; mapOperation - The map operation expression.
Returns:: The UnaryExpression expression.
See Also:: map expression documentation

millisecond
```
public static UnaryExpression millisecond(Expression expression)
```
Returns a UnaryExpression "$millisecond" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$millisecond" expression.

minute
```
public static UnaryExpression minute(Expression expression)
```
Returns a UnaryExpression "$minute" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$minute" expression.

mod
```
public static NaryExpression mod(Expression numerator,
                 Expression denominator)
```
Returns a NaryExpression "$mod" expression.

Parameters:
numerator - The numerator of the modulo operation.
denominator - The denominator of the modulo operation.

Returns:
The NaryExpression "$mod" expression.

month
```
public static UnaryExpression month(Expression expression)
```
Returns a UnaryExpression "$month" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$month" expression.

multiply
```
public static NaryExpression multiply(Expression lhs,
                      Expression rhs)
```
Returns a NaryExpression "$multiply" expression.

Parameters:
lhs - The left hand side of the operator.
rhs - The right hand side of the operator.

Returns:
The NaryExpression "$multiply" expression.

ne
```
public static NaryExpression ne(Expression lhs,
                Expression rhs)
```
Returns a NaryExpression "$ne" expression.

Parameters:
lhs - The left hand side of the comparison.
rhs - The right hand side of the comparison.

Returns:
The NaryExpression "$ne" expression.

not
```
public static UnaryExpression not(Expression expression)
```
Returns a UnaryExpression "$not" expression.

Parameters:
expression - The sub expressions for the $not.

Returns:
The UnaryExpression "$not" expression.

nullConstant
```
public static Constant nullConstant()
```
Returns a null Constant expression.

Returns:
The Constant expression.

or
```
public static NaryExpression or(Expression... expressions)
```
Returns an NaryExpression "$or" expression.

Parameters:
expressions - The sub-expressions.

Returns:
The NaryExpression "$or" expression.

second
```
public static UnaryExpression second(Expression expression)
```
Returns a UnaryExpression "$second" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$second" expression.

set
```
public static Element set(String name,
          DocumentAssignable document)
```
Returns an element to set the value to.

Parameters:
name - The name of the field to set.
document - The document to set the document to.

Returns:
The Element to set the value to the document.

set
```
public static Element set(String name,
          Expression expression)
```
Returns an element to set the value to.

Parameters:
name - The name of the field to set.
expression - The expression to compute the value for the field.

Returns:
The Element to set the value to the expression.

setDifference
```
public static NaryExpression setDifference(Expression lhs,
                           Expression rhs)
```
Returns a NaryExpression "$setDifference" expression.

Parameters:
lhs - The expression that will be evaluated to create the first set.
rhs - The expression that will be evaluated to create the second set.

Returns:
The NaryExpression "$setDifference" expression.

setEquals
```
public static NaryExpression setEquals(Expression lhs,
                       Expression rhs)
```
Returns a NaryExpression "$setEquals" expression.

Parameters:
lhs - The expression that will be evaluated to create the first set.
rhs - The expression that will be evaluated to create the second set.

Returns:
The NaryExpression "$setEquals" expression.

setIntersection
```
public static NaryExpression setIntersection(Expression lhs,
                             Expression rhs)
```
Returns a NaryExpression "$setIntersection" expression.

Parameters:
lhs - The expression that will be evaluated to create the first set.
rhs - The expression that will be evaluated to create the second set.

Returns:
The NaryExpression "$setIntersection" expression.

setIsSubset
```
public static NaryExpression setIsSubset(Expression subSet,
                         Expression completeSet)
```
Returns a NaryExpression "$setIsSubset" expression.

Parameters:
subSet - The expression that will be tested to see if it is a subset of the completeSet.
completeSet - The expression that will be evaluated to construct the complete set of values.

Returns:
The NaryExpression "$setIsSubset" expression.

setUnion
```
public static NaryExpression setUnion(Expression lhs,
                      Expression rhs)
```
Returns a NaryExpression "$setUnion" expression.

Parameters:
lhs - The expression that will be evaluated to create the first set.
rhs - The expression that will be evaluated to create the second set.

Returns:
The NaryExpression "$setUnion" expression.

size
```
public static UnaryExpression size(Expression expression)
```
Returns a UnaryExpression "$size" expression.

Parameters:
expression - The expression that will be evaluated to create the set to inspect for a true element.

Returns:
The UnaryExpression "$size" expression.

strcasecmp
```
public static NaryExpression strcasecmp(Expression lhs,
                        Expression rhs)
```
Returns a NaryExpression "$strcasecmp" expression.

Parameters:
lhs - The left hand side of the comparison.
rhs - The right hand side of the comparison.

Returns:
The NaryExpression "$strcasecmp" expression.

substr
```
public static NaryExpression substr(Expression string,
                    Expression skip,
                    Expression length)
```
Returns a NaryExpression "$substr" expression.

Parameters:
string - The string to pull a sub-string from.
skip - The number of characters to skip in the string.
length - The length of the string to extract.

Returns:
The NaryExpression "$substr" expression.

subtract
```
public static NaryExpression subtract(Expression lhs,
                      Expression rhs)
```
Returns a NaryExpression "$subtract" expression.

Parameters:
lhs - The left hand side of the operator.
rhs - The right hand side of the operator.

Returns:
The NaryExpression "$subtract" expression.

toLower
```
public static UnaryExpression toLower(Expression string)
```
Returns a UnaryExpression "$toLower" expression.

Parameters:
string - The string to modify.

Returns:
The UnaryExpression "$toLower" expression.

toUpper
```
public static UnaryExpression toUpper(Expression string)
```
Returns a UnaryExpression "$toUpper" expression.

Parameters:
string - The string to modify.

Returns:
The UnaryExpression "$toUpper" expression.

var
```
public static Constant var(String variableName)
```
Returns a Constant expression with the provided variableName. See the $let and $map expressions for example usage.
Prepends a $$ to the variable name if not already present.
```
 
 Constant variable = Expressions.var("variable");
 
 // Produces output: 
 //      $$variable
 System.out.println(variable);
 
 
```
Parameters:
variableName - The name of the field.

Returns:
The Constant expression.

week
```
public static UnaryExpression week(Expression expression)
```
Returns a UnaryExpression "$week" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$week" expression.

year
```
public static UnaryExpression year(Expression expression)
```
Returns a UnaryExpression "$year" expression.

Parameters:
expression - The date for the operator.

Returns:
The UnaryExpression "$year" expression.

Class Expressions

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ADD

ALL_ELEMENTS_TRUE

AND

ANY_ELEMENT_TRUE

COMPARE

CONCATENATE

CONDITION

DAY_OF_MONTH

DAY_OF_WEEK

DAY_OF_YEAR

DIVIDE

EQUAL

GREATER_THAN

GREATER_THAN_OR_EQUAL

HOUR

IF_NULL

LESS_THAN

LESS_THAN_OR_EQUAL

LITERAL

MILLISECOND

MINUTE

MODULO

MONTH

MULTIPLY

NOT

NOT_EQUAL

OR

SECOND

SET_DIFFERENCE

SET_EQUALS

SET_INTERSECTION

SET_IS_SUBSET

SET_UNION

SIZE

STRING_CASE_INSENSITIVE_COMPARE

SUB_STRING

SUBTRACT

TO_LOWER

TO_UPPER

WEEK

YEAR

Method Detail

add

allElementsTrue

and

anyElementTrue

cmp

concatenate

cond

constant

constant

constant

constant

constant

constant

constant

constant

constant

constantMongoTimestamp

constantTimestamp

dayOfMonth

dayOfWeek

dayOfYear

divide

eq

field

gt

gte

hour

ifNull

let

let

let

let

literal