Get a collection (C#)

Gets a reference to a collection for use with the Data API clients.

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 Collection object that corresponds to the specified collection name.

This method returns a Collection object even for collections that don’t exist.

By default, the Collection object is typed as Collection<Document>, where Document is Dictionary<string, object>. You can enable stronger typing by specifying a type when you get the collection. For more information and examples, see Custom typing for collections.

Signature

Use the GetCollection method, which belongs to the Database class.

public Collection<Document> GetCollection(
  string collectionName, GetCollectionOptions options = null
);

public Collection<T> GetCollection<T>(
  string collectionName, GetCollectionOptions options = null
) where T : class;

public Collection<T> GetCollection<T>(
  GetCollectionOptions options = null
) where T : class;

public Collection<T, TId> GetCollection<T, TId>(
  GetCollectionOptions options = null
) where T : class;

public Collection<T, TId> GetCollection<T, TId>(
  string collectionName, GetCollectionOptions options = null
) where T : class;

Parameters

Name Type Summary

Name	Type	Summary
`collectionName`	`string`	The name of the collection. If not specified, the client attempts to extract it from the `CollectionName` attribute on the custom document class if one is used. For more information and examples, see Custom typing for collections.
`options`	`GetCollectionOptions`	Optional. Options for this operation. Keyspace is required unless you specified a working keyspace when instantiating the `Database` object. For more information and examples for general options such as timeout and keyspace, see Customize API interaction.

collectionName

string

The name of the collection.

If not specified, the client attempts to extract it from the CollectionName attribute on the custom document class if one is used. For more information and examples, see Custom typing for collections.

options

GetCollectionOptions

Optional. Options for this operation. Keyspace is required unless you specified a working keyspace when instantiating the Database object. For more information and examples for general options such as timeout and keyspace, see Customize API interaction.

Examples

The following examples demonstrate how to get a collection.

Get a collection

Typed collections

You can manually define a client-side type for your collection to help statically catch errors. For more information and examples, see Custom typing for collections.

using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Collections;
using DataStax.AstraDB.DataApi.Core;
using DataStax.AstraDB.DataApi.SerDes;

namespace Examples;

// Define the type for the collection
[CollectionName("COLLECTION_NAME")]
public class User
{
  [DocumentId]
  public Guid? Id { get; set; }

  public string Name { get; set; } = null!;

  public int? Age { get; set; }
}

public class Program
{
  static void Main()
  {
    // Get a database
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

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

    // Get a collection
    var collection = database.GetCollection<User>();
  }
}

Untyped collections

If you don’t pass a type parameter, the collection or table remains untyped. This is a more flexible but less type-safe option.

using DataStax.AstraDB.DataApi;
using DataStax.AstraDB.DataApi.Core;

namespace Examples;

public class Program
{
  static void Main()
  {
    // Get a database
    var client = new DataAPIClient(
      new CommandOptions() { Destination = DataAPIDestination.HCD }
    );

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

    // Get a collection
    var collection = database.GetCollection("COLLECTION_NAME");
  }
}

Client reference

For more information, see the client reference.

Get a collection (C#)

Result

Signature

Parameters

Examples

Get a collection

Client reference

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