autocomplete¶

Definition¶

autocomplete¶

The autocomplete operator performs a search for a word or phrase that contains a sequence of characters from an incomplete input string. You can use the autocomplete operator with search-as-you-type applications to predict words with increasing accuracy as characters are entered in your application's search field. autocomplete returns results that contain predicted words based on the tokenization strategy specified in the index definition for autocompletion. The fields that you intend to query with the autocomplete operator must be indexed with the autocomplete data type in the collection's index definition.

Syntax¶

autocomplete 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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    "autocomplete": {
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      "query": "<search-string>",
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      "path": "<field-to-search>",
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      "tokenOrder": "any|sequential",
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      "fuzzy": <options>,
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      "score": <options>
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    }
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  }
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}

Options¶

Examples¶

The following examples use the movies collection in the sample_mflix database. If you loaded the sample dataset on your cluster, you can create the static index for autocompletion and run the example queries on your cluster.

The following tabs contain sample index definitions for the edgeGram, rightEdgeGram, and nGram tokenization strategies.

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db.movies.aggregate([
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  {
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    $search: {
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      "autocomplete": {
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        "path": "title",
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        "query": "off"
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      }
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    }
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  },
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  {
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    $limit: 10
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  },
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  {
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    $project: {
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      "_id": 0,
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      "title": 1
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    }
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  }
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])

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db.movies.aggregate([
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  {
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    $search: {
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      "autocomplete": {
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        "path": "title",
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        "query": "pre",
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        "fuzzy": {
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          "maxEdits": 1,
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          "prefixLength": 1,
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          "maxExpansions": 256
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        }
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      }
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    }
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  },
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  {
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    $limit: 10
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  },
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  {
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    $project: {
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      "_id": 0,
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      "title": 1
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    }
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  }
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])