$elemMatch (query)¶

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Definition
Behavior
Examples
Additional Examples

Definition¶

$elemMatch¶

The $elemMatch operator matches documents that contain an array field with at least one element that matches all the specified query criteria.

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{ <field>: { $elemMatch: { <query1>, <query2>, ... } } }

If you specify only a single <query> condition in the $elemMatch expression, you do not need to use $elemMatch.

Behavior¶

You cannot specify a $where expression in an $elemMatch.
You cannot specify a $text query expression in an $elemMatch.

Examples¶

Element Match¶

Given the following documents in the scores collection:

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{ _id: 1, results: [ 82, 85, 88 ] }
{ _id: 2, results: [ 75, 88, 89 ] }

The following query matches only those documents where the results array contains at least one element that is both greater than or equal to 80 and is less than 85.

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db.scores.find(
   { results: { $elemMatch: { $gte: 80, $lt: 85 } } }
)

The query returns the following document since the element 82 is both greater than or equal to 80 and is less than 85

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{ "_id" : 1, "results" : [ 82, 85, 88 ] }

For more information on specifying multiple criteria on array elements, see Specify Multiple Conditions for Array Elements.

Array of Embedded Documents¶

Given the following documents in the survey collection:

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{ _id: 1, results: [ { product: "abc", score: 10 }, { product: "xyz", score: 5 } ] }
{ _id: 2, results: [ { product: "abc", score: 8 }, { product: "xyz", score: 7 } ] }
{ _id: 3, results: [ { product: "abc", score: 7 }, { product: "xyz", score: 8 } ] }

The following query matches only those documents where the results array contains at least one element with both product equal to "xyz" and score greater than or equal to 8.

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db.survey.find(
   { results: { $elemMatch: { product: "xyz", score: { $gte: 8 } } } }
)

Specifically, the query matches the following document:

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{ "_id" : 3, "results" : [ { "product" : "abc", "score" : 7 }, { "product" : "xyz", "score" : 8 } ] }

Single Query Condition¶

If you specify a single query predicate in the $elemMatch expression, $elemMatch is not necessary.

For example, consider the following example where $elemMatch specifies only a single query predicate { product: "xyz" }:

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db.survey.find(
   { results: { $elemMatch: { product: "xyz" } } }
)

Since the $elemMatch only specifies a single condition, the $elemMatch expression is not necessary, and instead you can use the following query:

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db.survey.find(
   { "results.product": "xyz" }
)

Additional Examples¶

For additional examples in querying arrays, see:

For additional examples in querying, see:

Query Documents