AggregateCommand .allElementsTrue(value: Expression []): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

The aggregate operator. E nter an array, or an expression for an array field. I f all elements in the array are true, true is returned, otherwise false is returned. The empty array returns true forever.

Parameters

value: Expression[]

[<expression>]

Returns a value

Object

API description

The syntax is as follows:

allElementsTrue([<expression>])

The sample code

Suppose the collection test has the following records:

{ "_id": 1, "array": [ true ] }
{ "_id": 2, "array": [ ] }
{ "_id": 3, "array": [ false ] }
{ "_id": 4, "array": [ true, false ] }
{ "_id": 5, "array": [ 0 ] }
{ "_id": 6, "array": [ "stark" ] }

The following code uses allElementsTrue() to determine whether the array field is true:

const $ = db.command.aggregate
db.collection('price')
  .aggregate()
  .project({
    isAllTrue: $.allElementsTrue(['$array'])
  })
  .end()

The results are as follows:

{ "_id": 1, "isAllTrue": true }
{ "_id": 2, "isAllTrue": true }
{ "_id": 3, "isAllTrue": false }
{ "_id": 4, "isAllTrue": false }
{ "_id": 5, "isAllTrue": false }
{ "_id": 6, "isAllTrue": true }

---

AggregateCommand.anyElementTrue(value: Expression[]): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

The aggregate operator. E nter an array, or an expression for an array field. I f any of the elements in the array are true, true is returned, otherwise false is returned. An empty array returns false forever.

Parameters

value: Expression[]

[<expression>]

Returns a value

Object

API description

The syntax is as follows:

anyElementTrue([<expression>])

The sample code

Suppose the collection test has the following records:

{ "_id": 1, "array": [ true ] }
{ "_id": 2, "array": [ ] }
{ "_id": 3, "array": [ false ] }
{ "_id": 4, "array": [ true, false ] }
{ "_id": 5, "array": [ 0 ] }
{ "_id": 6, "array": [ "stark" ] }

The following code uses anyElementTrue() to determine if the array field contains a true value:

const $ = db.command.aggregate
db.collection('price')
  .aggregate()
  .project({
    isAnyTrue: $.anyElementTrue(['$array'])
  })
  .end()

The results are as follows:

{ "_id": 1, "isAnyTrue": true }
{ "_id": 2, "isAnyTrue": false }
{ "_id": 3, "isAnyTrue": false }
{ "_id": 4, "isAnyTrue": true }
{ "_id": 5, "isAnyTrue": false }
{ "_id": 6, "isAnyTrue": true }

---

AggregateCommand.setDifference(value: Expression[]): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

The aggregate operator enters two collections, and the output exists only in the elements in the first collection.

Parameters

value: Expression[]

[<expression1>, <expression2>]

Returns a value

Object

API description

This is used in the following form:

setDifference([<expression1>, <expression2>])

The sample code

Suppose the collection test has the following data:

{ "_id": 1, "A": [ 1, 2 ], "B": [ 1, 2 ] }
{ "_id": 2, "A": [ 1, 2 ], "B": [ 2, 1, 2 ] }
{ "_id": 3, "A": [ 1, 2 ], "B": [ 1, 2, 3 ] }
{ "_id": 4, "A": [ 1, 2 ], "B": [ 3, 1 ] }
{ "_id": 5, "A": [ 1, 2 ], "B": [ ] }
{ "_id": 6, "A": [ 1, 2 ], "B": [ {}, [] ] }
{ "_id": 7, "A": [ ], "B": [ ] }
{ "_id": 8, "A": [ ], "B": [ 1 ] }

The following code uses setDifference to find numbers that exist only in B:

db.collection('test')
  .aggregate()
  .project({
    isBOnly: $.setDifference(['$B', '$A'])
  })
  .end()

{ "_id": 1, "isBOnly": [] }
{ "_id": 2, "isBOnly": [3] }
{ "_id": 3, "isBOnly": [3] }
{ "_id": 4, "isBOnly": [5] }
{ "_id": 5, "isBOnly": [] }
{ "_id": 6, "isBOnly": [{}, []] }
{ "_id": 7, "isBOnly": [] }
{ "_id": 8, "isBOnly": [1] }

---

AggregateCommand.setEquals(value: Expression[]): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

Aggregate operators, enter two collections, and determine whether the elements contained in the two collections are the same (no order, de-weighting).

Parameters

value: Expression[]

[<expression1>, <expression2>]

Returns a value

Object

API description

This is used in the following form:

setEquals([<expression1>, <expression2>])

The sample code

Suppose the collection test has the following data:

{ "_id": 1, "A": [ 1, 2 ], "B": [ 1, 2 ] }
{ "_id": 2, "A": [ 1, 2 ], "B": [ 2, 1, 2 ] }
{ "_id": 3, "A": [ 1, 2 ], "B": [ 1, 2, 3 ] }
{ "_id": 4, "A": [ 1, 2 ], "B": [ 3, 1 ] }
{ "_id": 5, "A": [ 1, 2 ], "B": [ ] }
{ "_id": 6, "A": [ 1, 2 ], "B": [ {}, [] ] }
{ "_id": 7, "A": [ ], "B": [ ] }
{ "_id": 8, "A": [ ], "B": [ 1 ] }

The following code uses setEquals to determine whether the elements contained in the two collections are the same:

db.collection('test')
  .aggregate()
  .project({
    sameElements: $.setEquals(['$A', '$B'])
  })
  .end()

{ "_id": 1, "sameElements": true }
{ "_id": 2, "sameElements": true }
{ "_id": 3, "sameElements": false }
{ "_id": 4, "sameElements": false }
{ "_id": 5, "sameElements": false }
{ "_id": 6, "sameElements": false }
{ "_id": 7, "sameElements": true }
{ "_id": 8, "sameElements": false }

---

AggregateCommand.setIntersection(value: Expression[]): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

Aggregate operators, enter two collections, and output the intersection of two collections.

Parameters

value: Expression[]

[<expression1>, <expression2>]

Returns a value

Object

API description

This is used in the following form:

setIntersection([<expression1>, <expression2>])

The sample code

Suppose the collection test has the following data:

{ "_id": 1, "A": [ 1, 2 ], "B": [ 1, 2 ] }
{ "_id": 2, "A": [ 1, 2 ], "B": [ 2, 1, 2 ] }
{ "_id": 3, "A": [ 1, 2 ], "B": [ 1, 2, 3 ] }
{ "_id": 4, "A": [ 1, 2 ], "B": [ 3, 1 ] }
{ "_id": 5, "A": [ 1, 2 ], "B": [ ] }
{ "_id": 6, "A": [ 1, 2 ], "B": [ {}, [] ] }
{ "_id": 7, "A": [ ], "B": [ ] }
{ "_id": 8, "A": [ ], "B": [ 1 ] }

The following code uses setIntersection to output the intersection of two collections:

db.collection('test')
  .aggregate()
  .project({
    commonToBoth: $.setIntersection(['$A', '$B'])
  })
  .end()

The output is as follows:

{ "_id": 1, "commonToBoth": [ 1, 2 ] }
{ "_id": 2, "commonToBoth": [ 1, 2 ] }
{ "_id": 3, "commonToBoth": [ 1, 2 ] }
{ "_id": 4, "commonToBoth": [ 1 ] }
{ "_id": 5, "commonToBoth": [ ] }
{ "_id": 6, "commonToBoth": [ ] }
{ "_id": 7, "commonToBoth": [ ] }
{ "_id": 8, "commonToBoth": [ ] }

---

AggregateCommand.setIsSubset(value: Expression[]): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

Aggregate operators, enter two collections, and determine whether the first collection is a subset of the second collection.

Parameters

value: Expression[]

[<expression1>, <expression2>]

Returns a value

Object

API description

This is used in the following form:

setIsSubset([<expression1>, <expression2>])

The sample code

Suppose the collection test has the following data:

{ "_id": 1, "A": [ 1, 2 ], "B": [ 1, 2 ] }
{ "_id": 2, "A": [ 1, 2 ], "B": [ 2, 1, 2 ] }
{ "_id": 3, "A": [ 1, 2 ], "B": [ 1, 2, 3 ] }
{ "_id": 4, "A": [ 1, 2 ], "B": [ 3, 1 ] }
{ "_id": 5, "A": [ 1, 2 ], "B": [ ] }
{ "_id": 6, "A": [ 1, 2 ], "B": [ {}, [] ] }
{ "_id": 7, "A": [ ], "B": [ ] }
{ "_id": 8, "A": [ ], "B": [ 1 ] }

The following code uses setIsSubset to determine whether the first collection is a subset of the second collection:

db.collection('test')
  .aggregate()
  .project({
    AisSubsetOfB: $.setIsSubset(['$A', '$B'])
  })
  .end()

{ "_id": 1, "AisSubsetOfB": true }
{ "_id": 2, "AisSubsetOfB": true }
{ "_id": 3, "AisSubsetOfB": true }
{ "_id": 4, "AisSubsetOfB": false }
{ "_id": 5, "AisSubsetOfB": false }
{ "_id": 6, "AisSubsetOfB": false }
{ "_id": 7, "AisSubsetOfB": true }
{ "_id": 8, "AisSubsetOfB": true }

---

AggregateCommand.setUnion(value: Expression[]): Object

Support: Small program 2.7.4, cloud function 0.8.1, Web

Aggregate operators, enter two collections, and output the contrase of two collections.

Parameters

value: Expression[]

[<expression1>, <expression2>]

Returns a value

Object

API description

This is used in the following form:

setUnion([<expression1>, <expression2>])

The sample code

Suppose the collection test has the following data:

{ "_id": 1, "A": [ 1, 2 ], "B": [ 1, 2 ] }
{ "_id": 2, "A": [ 1, 2 ], "B": [ 2, 1, 2 ] }
{ "_id": 3, "A": [ 1, 2 ], "B": [ 1, 2, 3 ] }
{ "_id": 4, "A": [ 1, 2 ], "B": [ 3, 1 ] }
{ "_id": 5, "A": [ 1, 2 ], "B": [ ] }
{ "_id": 6, "A": [ 1, 2 ], "B": [ {}, [] ] }
{ "_id": 7, "A": [ ], "B": [ ] }
{ "_id": 8, "A": [ ], "B": [ 1 ] }

The following code uses setUnion to output a union of two collections:

db.collection('test')
  .aggregate()
  .project({
    AB: $.setUnion(['$A', '$B'])
  })
  .end()

The output is as follows:

{ "_id": 1, "AB": [ 1, 2 ] }
{ "_id": 2, "AB": [ 1, 2 ] }
{ "_id": 3, "AB": [ 1, 2, 3 ] }
{ "_id": 4, "AB": [ 1, 2, 3 ] }
{ "_id": 5, "AB": [ 1, 2 ] }
{ "_id": 6, "AB": [ 1, 2, {}, [] ] }
{ "_id": 7, "AB": [ ] }
{ "_id": 8, "AB": [ 1 ] }