$all¶

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Behavior
Examples

$all¶

The $all operator selects the documents where the value of a field is an array that contains all the specified elements. To specify an $all expression, use the following prototype:

{ <field>: { $all: [ <value1> , <value2> ... ] } }

Behavior¶

Equivalent to `$and` Operation¶

Changed in version 2.6.

The $all is equivalent to an $and operation of the specified values; i.e. the following statement:

{ tags: { $all: [ "ssl" , "security" ] } }

is equivalent to:

{ $and: [ { tags: "ssl" }, { tags: "security" } ] }

Nested Array¶

Changed in version 2.6.

When passed an array of a nested array (e.g. [ [ "A" ] ] ), $all can now match documents where the field contains the nested array as an element (e.g. field: [ [ "A" ], ... ]), or the field equals the nested array (e.g. field: [ "A" ]).

For example, consider the following query [1]:

db.articles.find( { tags: { $all: [ [ "ssl", "security" ] ] } } )

The query is equivalent to:

db.articles.find( { $and: [ { tags: [ "ssl", "security" ] } ] } )

which is equivalent to:

db.articles.find( { tags: [ "ssl", "security" ] } )

As such, the $all expression can match documents where the tags field is an array that contains the nested array [ "ssl", "security" ] or is an array that equals the nested array:

tags: [ [ "ssl", "security" ], ... ]
tags: [ "ssl", "security" ]

This behavior for $all allows for more matches than previous versions of MongoDB. Earlier versions could only match documents where the field contains the nested array.

[1]	The `$all` expression with a single element is for illustrative purposes since the `$all` expression is unnecessary if matching only a single element. Instead, when matching a single element, a “contains” expression (i.e. `arrayField: element` ) is more suitable.

Performance¶

Queries that use the $all operator must scan all the documents that match the first element in the $all expression. As a result, even with an index to support the query, the operation may be long running, particularly when the first element in the $all expression is not very selective.

Examples¶

The following examples use the inventory collection that contains the documents:

{
   _id: ObjectId("5234cc89687ea597eabee675"),
   code: "xyz",
   tags: [ "school", "book", "bag", "headphone", "appliance" ],
   qty: [
          { size: "S", num: 10, color: "blue" },
          { size: "M", num: 45, color: "blue" },
          { size: "L", num: 100, color: "green" }
        ]
}

{
   _id: ObjectId("5234cc8a687ea597eabee676"),
   code: "abc",
   tags: [ "appliance", "school", "book" ],
   qty: [
          { size: "6", num: 100, color: "green" },
          { size: "6", num: 50, color: "blue" },
          { size: "8", num: 100, color: "brown" }
        ]
}

{
   _id: ObjectId("5234ccb7687ea597eabee677"),
   code: "efg",
   tags: [ "school", "book" ],
   qty: [
          { size: "S", num: 10, color: "blue" },
          { size: "M", num: 100, color: "blue" },
          { size: "L", num: 100, color: "green" }
        ]
}

{
   _id: ObjectId("52350353b2eff1353b349de9"),
   code: "ijk",
   tags: [ "electronics", "school" ],
   qty: [
          { size: "M", num: 100, color: "green" }
        ]
}

Use `$all` to Match Values¶

The following operation uses the $all operator to query the inventory collection for documents where the value of the tags field is an array whose elements include appliance, school, and book:

db.inventory.find( { tags: { $all: [ "appliance", "school", "book" ] } } )

The above query returns the following documents:

{
   _id: ObjectId("5234cc89687ea597eabee675"),
   code: "xyz",
   tags: [ "school", "book", "bag", "headphone", "appliance" ],
   qty: [
          { size: "S", num: 10, color: "blue" },
          { size: "M", num: 45, color: "blue" },
          { size: "L", num: 100, color: "green" }
        ]
}

{
   _id: ObjectId("5234cc8a687ea597eabee676"),
   code: "abc",
   tags: [ "appliance", "school", "book" ],
   qty: [
          { size: "6", num: 100, color: "green" },
          { size: "6", num: 50, color: "blue" },
          { size: "8", num: 100, color: "brown" }
        ]
}

Use `$all` with `$elemMatch`¶

If the field contains an array of documents, you can use the $all with the $elemMatch operator.

The following operation queries the inventory collection for documents where the value of the qty field is an array whose elements match the $elemMatch criteria:

db.inventory.find( {
                     qty: { $all: [
                                    { "$elemMatch" : { size: "M", num: { $gt: 50} } },
                                    { "$elemMatch" : { num : 100, color: "green" } }
                                  ] }
                   } )

The query returns the following documents:

{
   "_id" : ObjectId("5234ccb7687ea597eabee677"),
   "code" : "efg",
   "tags" : [ "school", "book"],
   "qty" : [
             { "size" : "S", "num" : 10, "color" : "blue" },
             { "size" : "M", "num" : 100, "color" : "blue" },
             { "size" : "L", "num" : 100, "color" : "green" }
           ]
}

{
   "_id" : ObjectId("52350353b2eff1353b349de9"),
   "code" : "ijk",
   "tags" : [ "electronics", "school" ],
   "qty" : [
             { "size" : "M", "num" : 100, "color" : "green" }
           ]
}

The $all operator exists to support queries on arrays. But you may use the $all operator to select against a non-array field, as in the following example:

db.inventory.find( { "qty.num": { $all: [ 50 ] } } )

However, use the following form to express the same query:

db.inventory.find( { "qty.num" : 50 } )

Both queries will select all documents in the inventory collection where the value of the num field equals 50.

Note

In most cases, MongoDB does not treat arrays as sets. This operator provides a notable exception to this approach.