Find a document (TypeScript)

Finds a single document in a collection using filter and sort clauses, including vector search.

Ready to write code? See the examples for this method to get started. If you are new to the Data API, check out the quickstart.

Result

Returns a promise that resolves to a document that matches the specified filter and sort clauses, or to null if no document was found.

The fields included in the returned document depend on the subset of fields that were requested in the projection. If requested and applicable, the document will also include a $similarity key with a numeric similarity score that represents the closeness of the sort vector and the document’s vector.

Example response:

{'_id': 101, 'name': 'John Doe', '$vector': [0.12, 0.52, 0.32]}

Parameters

Use the findOne method, which belongs to the Collection class.

Method signature

async findOne(
  filter: CollectionFilter<Schema>,
  options?: {
    sort?: Sort,
    projection?: Projection,
    timeout?: number | TimeoutDescriptor,
  },
): Schema | null

Name Type Summary

Name	Type	Summary
`filter`	`CollectionFilter<Schema>`	An object that defines filter criteria using the Data API filter syntax. The method only finds documents that match the filter criteria. Filters can improve performance by reducing the number of documents that the Data API processes. You must use `&` to escape any `.` or `&` in field names in the filter clause. You cannot use `&` to escape any other characters. For more information, see Work with `.` and `&` in field names (TypeScript). For a list of available filter operators and more examples, see Filter operators for collections (TypeScript). Filters can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in a filter. For an example, see Use filters to find a document.
`options`	`CollectionFindOneOptions`	Optional. The options for this operation. See Properties of `options` for more details.

filter

CollectionFilter<Schema>

An object that defines filter criteria using the Data API filter syntax. The method only finds documents that match the filter criteria. Filters can improve performance by reducing the number of documents that the Data API processes.

You must use & to escape any . or & in field names in the filter clause. You cannot use & to escape any other characters. For more information, see Work with . and & in field names (TypeScript).

For a list of available filter operators and more examples, see Filter operators for collections (TypeScript).

Filters can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in a filter.

For an example, see Use filters to find a document.

options

CollectionFindOneOptions

Optional. The options for this operation. See Properties of options for more details.

Properties of `options`
Name	Type	Summary
`projection`	`Projection`	Optional. Controls which fields are included or excluded in the returned document. You must use `&` to escape any `.` or `&` in field names in the projection clause. You cannot use `&` to escape any other characters. For more information, see Work with `.` and `&` in field names (TypeScript). For more information, see Projections for collections (TypeScript). Default: The default projection for the collection. All fields prefixed with `$` are excluded by default and will only be returned if you include them in the projection. `_id` is included by default and will always be returned unless you exclude it from the projection. For examples, see Include only specific fields in the response and Exclude specific fields from the response.
`sort`	`Sort`	Optional. Sorts documents by one or more fields, or performs a vector search. You must use `&` to escape any `.` or `&` in field names in the sort clause. You cannot use `&` to escape any other characters. For more information, see Work with `.` and `&` in field names (TypeScript). For more information, see Sort clauses for collections (TypeScript). Sort clauses can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in sort queries. For vector searches, this parameter can use `$vector`. For examples, see Use sorting to find a document and Use vector search to find a document.
`timeout`	`number` \| `TimeoutDescriptor`	Optional. The timeout(s) to apply to this method. You can specify `requestTimeoutMs` and `generalMethodTimeoutMs`. Since this method issues a single HTTP request, these timeouts are equivalent. If you specify both, the minimum of the two will be used. For more information about the `TimeoutDescriptor`, see TypeScript client internals: TimeoutDescriptor. If you specify a number instead of a `TimeoutDescriptor` object, that number will be applied to both `requestTimeoutMs` and `generalMethodTimeoutMs`.

Examples

The following examples demonstrate how to find a document in a collection.

Use a document’s ID to find a document

All documents have a unique _id property. You can use a filter to find a document with a specific _id.

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne({ _id: "101" });

  console.log(result);
})();

Use filters to find a document

You can use a filter to find a document that matches specific criteria. For example, you can find a document with an is_checked_out value of false and a number_of_pages value less than 300.

For a list of available filter operators and more examples, see Filter operators for collections (TypeScript).

Filters can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in a filter.

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne({
    $and: [{ is_checked_out: false }, { number_of_pages: { $lt: 300 } }],
  });

  console.log(result);
})();

Use vector search to find a document

To find the document whose $vector value is most similar to a given vector, use a sort with the vector embeddings that you want to match. For more information, see Find data with vector search.

Vector search is only available for vector-enabled collections. For more information, see Create a collection that can store vector embeddings and $vector in collections (TypeScript).

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    {},
    { sort: { $vector: [0.08, -0.62, 0.39] } },
  );

  console.log(result);
})();

Use lexicographical matching to find a document

Lexicographical matching is currently in public preview. Development is ongoing, and the features and functionality are subject to change. Hyper-Converged Database (HCD), and the use of such, is subject to the DataStax Preview Terms.

There are two ways to use lexicographical matching to find documents with the Data API:

Sort on the $lexical field to find the documents whose $lexical field value is most relevant to a given string of space-separated keywords or terms
Filter on the $lexical field with the $match operator to find the documents whose $lexical field value is a lexicographical match to the specified string of space-separated keywords or terms

You can use these strategies together or separately.

You can only use lexicographical matching on collections that have lexical enabled. For more information, see Create a collection that supports lexicographical matching.

Documents must have the $lexical field populated to be included in lexicographical matching. For examples, see Insert a document for retrieval with lexicographical matching and Insert documents for retrieval with lexicographical matching.

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    { $lexical: { $match: "tree hill" } },
    { sort: { $lexical: "tree hill grassy" } },
  );

  console.log(result);
})();

Use sorting to find a document

You can use a sort clause to sort documents by one or more fields.

For more information, see Sort clauses for collections (TypeScript).

Sort clauses can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in sort queries.

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    { "metadata.language": "English" },
    {
      sort: {
        rating: 1, // ascending
        title: -1, // descending
      },
    },
  );

  console.log(result);
})();

Include only specific fields in the response

To specify which fields to include or exclude in the returned document, use a projection.

All fields prefixed with $ are excluded by default and will only be returned if you include them in the projection. _id is included by default and will always be returned unless you exclude it from the projection.

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    { "metadata.language": "English" },
    { projection: { is_checked_out: true, title: true } },
  );

  console.log(result);
})();

Exclude specific fields from the response

To specify which fields to include or exclude in the returned document, use a projection.

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    { "metadata.language": "English" },
    { projection: { is_checked_out: false, title: false } },
  );

  console.log(result);
})();

Use filter, sort, and projection together

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    {
      $and: [{ is_checked_out: false }, { number_of_pages: { $lt: 300 } }],
    },
    {
      sort: {
        rating: 1, // ascending
        title: -1, // descending
      },
      projection: {
        is_checked_out: true,
        title: true,
      },
    },
  );

  console.log(result);
})();

Work with `.` and `&` in field names

You must use & to escape any . or & in field names when the field is used in a filter, sort, projection, update, or indexing clause. Dot notation, which is used to reference nested fields, should not be escaped. For more information, see Work with . and & in field names (TypeScript).

For example, in the following document, you would use escaping like this: areas.r&&d, costs.price&.usd, and costs.price&.cad.

{
  "areas": {
    "r&d": true,
    "design": false
  },
  "costs": {
    "price.usd": 100,
    "price.cad": 90
  }
}

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    {
      $and: [{ "areas.r&&d": false }, { "costs.price&.usd": { $lt: 300 } }],
    },
    {
      sort: {
        "costs.price&.usd": 1, // ascending
      },
      projection: {
        "areas.r&&d": true,
        "costs.price&.cad": true,
      },
    },
  );

  console.log(result);
})();

You can also use the escapeFieldNames function provided by the client:

import {
  DataAPIClient,
  UsernamePasswordTokenProvider,
  escapeFieldNames,
} from "@datastax/astra-db-ts";

// Get an existing collection
const client = new DataAPIClient({ environment: "hcd" });
const database = client.db("API_ENDPOINT", {
  token: new UsernamePasswordTokenProvider("USERNAME", "PASSWORD"),
  keyspace: "KEYSPACE_NAME",
});
const collection = database.collection("COLLECTION_NAME");

// Find a document
(async function () {
  const result = await collection.findOne(
    {
      $and: [
        { [escapeFieldNames("areas", "r&d")]: false },
        { [escapeFieldNames("costs", "price.usd")]: { $lt: 300 } },
      ],
    },
    {
      sort: {
        [escapeFieldNames("costs", "price.usd")]: 1, // ascending
      },
      projection: {
        [escapeFieldNames("areas", "r&d")]: true,
        [escapeFieldNames("costs", "price.cad")]: true,
      },
    },
  );

  console.log(result);
})();

Client reference

For more information, see the client reference.

Find a document (TypeScript)

Result

Parameters

Examples

Use a document’s ID to find a document

Use filters to find a document

Use vector search to find a document

Use lexicographical matching to find a document

Use sorting to find a document

Include only specific fields in the response

Exclude specific fields from the response

Use filter, sort, and projection together

Work with `.` and `&` in field names

Client reference

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