Find and delete a document (C#)

Finds a single document in a collection using filter and sort clauses, and then deletes that document.

This method and the method to delete a document have the same database effect but differ in their return value. This method returns the document that was found and deleted. The method to delete a document returns details about the success of the deletion.

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

Deletes a document that matches the specified parameters, and returns the document. Returns null if no document was found.

The fields included in the returned document depend on the projection specified in the method.

Parameters

Use the FindOneAndDeleteAsync method, which belongs to the Collection class. You can also use FindOneAndDelete, which is the synchronous version of the method.

Method signature 
public Task<T> FindOneAndDeleteAsync(
  CollectionFilter<T> filter,
  CollectionFindOneAndDeleteOptions<T> options = null
);
public Task<TResult> FindOneAndDeleteAsync<TResult>(
  CollectionFilter<T> filter,
  CollectionFindOneAndDeleteOptions<T> options = null
);
Name Type Summary

filter

CollectionFilter

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 (C#).

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

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 Delete a document that matches a filter.

options

CollectionFindOneAndDeleteOptions

Optional. Options for this operation. For more information and examples for general options such as timeout, see Customize API interaction. For options specific to this method, see Method-specific properties of the CollectionFindOneAndDeleteOptions class.
Method-specific properties of the CollectionFindOneAndDeleteOptions class
Name Type Summary

Sort

SortBuilder<T>

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 (C#).

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

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 Delete a document after applying a non-vector sort and Delete a document that is most similar to a search vector.

Projection

IProjectionBuilder

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 (C#).

For more information, see Projections for collections (C#).

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.

Examples

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

Delete a document by ID

All documents have a unique _id property. You can use a filter to find a document with a specific _id, and then delete that document.

The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.

using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static async Task Main()
  {
    // Get an existing collection
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

    var database = client.GetDatabase(
      "API_ENDPOINT",
      DataAPIClient.UsernamePasswordTokenProvider(
        "USERNAME",
        "PASSWORD"
      ),
      "KEYSPACE_NAME"
    );

    var collection = database.GetCollection("COLLECTION_NAME");

    // Delete a document
    var filter = Builders<Document>.CollectionFilter.Eq("_id", "101");
    var result = await collection.FindOneAndDeleteAsync(filter);

    Console.WriteLine(JsonSerializer.Serialize(result));
  }
}

Delete a document that matches a filter

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 (C#).

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.

The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.

using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static async Task Main()
  {
    // Get an existing collection
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

    var database = client.GetDatabase(
      "API_ENDPOINT",
      DataAPIClient.UsernamePasswordTokenProvider(
        "USERNAME",
        "PASSWORD"
      ),
      "KEYSPACE_NAME"
    );

    var collection = database.GetCollection("COLLECTION_NAME");

    // Delete a document
    var filterBuilder = Builders<Document>.CollectionFilter;
    var filter = filterBuilder.And(
      filterBuilder.Eq("is_checked_out", false),
      filterBuilder.Lt("number_of_pages", 300)
    );
    var result = await collection.FindOneAndDeleteAsync(filter);

    Console.WriteLine(JsonSerializer.Serialize(result));
  }
}

Delete a document that is most similar to a search vector

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 (C#).

The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.

using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static async Task Main()
  {
    // Get an existing collection
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

    var database = client.GetDatabase(
      "API_ENDPOINT",
      DataAPIClient.UsernamePasswordTokenProvider(
        "USERNAME",
        "PASSWORD"
      ),
      "KEYSPACE_NAME"
    );

    var collection = database.GetCollection("COLLECTION_NAME");

    // Delete a document
    var embeddings = new float[] { 0.08f, -0.62f, 0.39f };
    var findOptions = new CollectionFindOneAndDeleteOptions<Document>()
    {
      Sort = Builders<Document>.CollectionSort.Vector(embeddings),
    };
    var result = await collection.FindOneAndDeleteAsync(
      null,
      findOptions
    );

    Console.WriteLine(JsonSerializer.Serialize(result));
  }
}

Delete a document after applying a non-vector sort

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

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

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.

The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.

using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static async Task Main()
  {
    // Get an existing collection
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

    var database = client.GetDatabase(
      "API_ENDPOINT",
      DataAPIClient.UsernamePasswordTokenProvider(
        "USERNAME",
        "PASSWORD"
      ),
      "KEYSPACE_NAME"
    );

    var collection = database.GetCollection("COLLECTION_NAME");

    // Delete a document
    var filter = Builders<Document>.CollectionFilter.Eq(
      "metadata.language",
      "English"
    );
    var findOptions = new CollectionFindOneAndDeleteOptions<Document>()
    {
      Sort = Builders<Document>
        .CollectionSort.Ascending("rating")
        .Descending("title"),
    };
    var result = await collection.FindOneAndDeleteAsync(
      filter,
      findOptions
    );

    Console.WriteLine(JsonSerializer.Serialize(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.

The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.

using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static async Task Main()
  {
    // Get an existing collection
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

    var database = client.GetDatabase(
      "API_ENDPOINT",
      DataAPIClient.UsernamePasswordTokenProvider(
        "USERNAME",
        "PASSWORD"
      ),
      "KEYSPACE_NAME"
    );

    var collection = database.GetCollection("COLLECTION_NAME");

    // Delete a document
    var filter = Builders<Document>.CollectionFilter.Eq(
      "metadata.language",
      "English"
    );
    var findOptions = new CollectionFindOneAndDeleteOptions<Document>()
    {
      Projection = Builders<Document>
        .Projection.Include("is_checked_out")
        .Include("title"),
    };
    var result = await collection.FindOneAndDeleteAsync(
      filter,
      findOptions
    );

    Console.WriteLine(JsonSerializer.Serialize(result));
  }
}

Exclude specific fields from 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.

The following example uses untyped documents, but you can use strongly-typed classes for compile-time checks and IntelliSense. For more information and examples, see Custom typing for collections.

using System.Text.Json;
using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static async Task Main()
  {
    // Get an existing collection
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

    var database = client.GetDatabase(
      "API_ENDPOINT",
      DataAPIClient.UsernamePasswordTokenProvider(
        "USERNAME",
        "PASSWORD"
      ),
      "KEYSPACE_NAME"
    );

    var collection = database.GetCollection("COLLECTION_NAME");

    // Delete a document
    var filter = Builders<Document>.CollectionFilter.Eq(
      "metadata.language",
      "English"
    );
    var findOptions = new CollectionFindOneAndDeleteOptions<Document>()
    {
      Projection = Builders<Document>
        .Projection.Exclude("is_checked_out")
        .Exclude("title"),
    };
    var result = await collection.FindOneAndDeleteAsync(
      filter,
      findOptions
    );

    Console.WriteLine(JsonSerializer.Serialize(result));
  }
}

Client reference

For more information, see the client reference.

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