FEATURE DESCRIPTION
MongoDB 3.5.12 extends all update modifiers to apply to all array elements or all array elements that match a predicate, specified in a new update option arrayFilters. This syntax also supports nested array elements.
VERSIONS
This new feature is available starting with the MongoDB 3.5.12 development version, and included in the MongoDB 3.6 production version.
OPERATION
Update all documents in array
db.coll.update({}, {$set: {“a.$[].b”: 2}}) Input: {a: [{b: 0}, {b: 1}]} Output: {a: [{b: 2}, {b: 2}]}
Update all matching documents in array
db.coll.update({}, {$set: {“a.$[i].b”: 2}}, {arrayFilters: [{“i.b”: 0}]}) Input: {a: [{b: 0}, {b: 1}]} Output: {a: [{b: 2}, {b: 1}]}
Update all matching scalars in array
db.coll.update({}, {$set: {“a.$[i]”: 2}}, {arrayFilters: [{i: 0}]}) Input: {a: [0, 1]} Output: {a: [2, 1]}
Update all matching documents in nested array
db.coll.update({}, {$set: {“a.$[i].c.$[j].d”: 2}}, {arrayFilters: [{“i.b”: 0}, {“j.d”: 0}]}) Input: {a: [{b: 0, c: [{d: 0}, {d: 1}]}, {b: 1, c: [{d: 0}, {d: 1}]}]} Output: {a: [{b: 0, c: [{d: 2}, {d: 1}]}, {b: 1, c: [{d: 0}, {d: 1}]}]}
Update all scalars in array matching a logical predicate
db.coll.update({}, {$set: {“a.$[i]”: 2}}, {arrayFilters: [{$or: [{i: 0}, {i: 3}]}]}) Input: {a: [0, 1, 3]} Output: {a: [2, 1, 2]}
Each array filter must be a predicate over a document with a single field name. Each array filter must be used in the update expression, and each array filter identifier $[<id>] must have a corresponding array filter. <id> must begin with a lowercase letter and not contain any special characters. There must not be two array filters with the same field name.
IMPLEMENTATION DETAILS
The implementation of this feature involved a rewrite of the update system. Users can find all the related tickets here. The design document is attached.
Original description
- is depended on by
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SERVER-6982 positional operator does not work with negated match expressions
- Closed
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SERVER-831 Positional Operator Matching Nested Arrays
- Closed
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SERVER-1243 New operator to update all matching items in an array
- Closed
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SERVER-2476 New $update atomic modifier for changing array elements
- Closed
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SERVER-25717 Allow for negative $push indexes.
- Closed
-
SERVER-1050 not allowed to $push and $pop to same field in same update
- Closed
- is duplicated by
-
SERVER-6982 positional operator does not work with negated match expressions
- Closed
-
SERVER-29526 Updating the specific array in nested subdocument
- Closed
- is related to
-
SERVER-25717 Allow for negative $push indexes.
- Closed
- related to
-
SERVER-30998 Update and $ operator mismatch with multiple arrays in query
- Closed