exists (MongoDB Search Operator)

Definition

exists

The exists operator tests if a path to a specified indexed field name exists in a document. If the specified field exists but is not indexed, the document is not included with the result set. exists is often used as part of a compound query in conjunction with other search clauses.

Syntax

exists has the following syntax:

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{
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  $search: {
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    "index": <index name>, // optional, defaults to "default"
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    "exists": {
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      "path": "<field-to-test-for>",
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      "score": <options>
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    }
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  }
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}

Options

exists uses the following terms to construct a query:

Scoring Behavior

MongoDB Search assigns a constant score of 1 for all the documents in the result set. You can customize the default MongoDB Search score using the score options. To learn more about modifying the default score returned by MongoDB Search, see Modify the Score.

Examples

You can try the following examples in the MongoDB Search Playground or your cluster.

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{
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  "_id" : 1,
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  "type" : "apple",
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  "description" : "Apples come in several varieties, including Fuji, Granny Smith, and Honeycrisp."
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},
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{
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  "_id" : 2,
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  "type" : "banana",
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  "description" : "Bananas are usually sold in bunches of five or six."
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},
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{ "_id" : 3,
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  "type": "apple",
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  "description" : "Apple pie and apple cobbler are popular apple-based desserts."
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},
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{ "_id" : 4,
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  "description" : "Types of citrus fruit include lemons, oranges, and grapefruit.",
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  "quantities" : {
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    "lemons": 200,
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    "oranges": 240,
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    "grapefruit": 160
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  }
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}

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db.fruit.aggregate([
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  {
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    $search: {
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      "exists": {
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        "path": "type"
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      }
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    }
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  }
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])

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db.fruit.aggregate([
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  {
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    "$search": {
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      "exists": {
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        "path": "quantities.lemons"
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      }
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    }
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  }
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])

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{
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  "_id" : 4,
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  "description" : "Types of citrus fruit include lemons, oranges, and grapefruit.",
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  "quantities" : {
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    "lemons": 200,
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    "oranges": 240,
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    "grapefruit": 160
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  }
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}

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db.fruit.aggregate([
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  {
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    $search: {
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      "compound": {
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        "must": [
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          {
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            "exists": {
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              "path": "type"
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            }
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          },
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          {
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            "text": {
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              "query": "apple",
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              "path": "type"
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            }
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          }],
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        "should": {
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          "text": {
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            "query": "fuji",
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            "path": "description"
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          }
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        }
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      }
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    }
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  }
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])

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{
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  "_id" : 1,
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  "type" : "apple",
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  "description" : "Apples come in several varieties, including Fuji, Granny Smith, and Honeycrisp."
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}
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{
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  "_id" : 3,
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  "type" : "apple",
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  "description" : "Apple pie and apple cobbler are popular apple-based desserts."
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}