# ListChannelNamespaces
<a name="API_ListChannelNamespaces"></a>

Lists the channel namespaces for a specified `Api`.

 `ListChannelNamespaces` returns only high level details for the channel namespace. To retrieve code handlers, use `GetChannelNamespace`.

## Request Syntax
<a name="API_ListChannelNamespaces_RequestSyntax"></a>

```
GET /v2/apis/apiId/channelNamespaces?maxResults=maxResults&nextToken=nextToken HTTP/1.1
```

## URI Request Parameters
<a name="API_ListChannelNamespaces_RequestParameters"></a>

The request uses the following URI parameters.

 ** [apiId](#API_ListChannelNamespaces_RequestSyntax) **   <a name="appsync-ListChannelNamespaces-request-uri-apiId"></a>
The `Api` ID.  
Required: Yes

 ** [maxResults](#API_ListChannelNamespaces_RequestSyntax) **   <a name="appsync-ListChannelNamespaces-request-uri-maxResults"></a>
The maximum number of results that you want the request to return.  
Valid Range: Minimum value of 0. Maximum value of 25.

 ** [nextToken](#API_ListChannelNamespaces_RequestSyntax) **   <a name="appsync-ListChannelNamespaces-request-uri-nextToken"></a>
An identifier that was returned from the previous call to this operation, which you can use to return the next set of items in the list.  
Length Constraints: Minimum length of 1. Maximum length of 65536.  
Pattern: `[\S]+` 

## Request Body
<a name="API_ListChannelNamespaces_RequestBody"></a>

The request does not have a request body.

## Response Syntax
<a name="API_ListChannelNamespaces_ResponseSyntax"></a>

```
HTTP/1.1 200
Content-type: application/json

{
   "channelNamespaces": [ 
      { 
         "apiId": "string",
         "channelNamespaceArn": "string",
         "codeHandlers": "string",
         "created": number,
         "handlerConfigs": { 
            "onPublish": { 
               "behavior": "string",
               "integration": { 
                  "dataSourceName": "string",
                  "lambdaConfig": { 
                     "invokeType": "string"
                  }
               }
            },
            "onSubscribe": { 
               "behavior": "string",
               "integration": { 
                  "dataSourceName": "string",
                  "lambdaConfig": { 
                     "invokeType": "string"
                  }
               }
            }
         },
         "lastModified": number,
         "name": "string",
         "publishAuthModes": [ 
            { 
               "authType": "string"
            }
         ],
         "subscribeAuthModes": [ 
            { 
               "authType": "string"
            }
         ],
         "tags": { 
            "string" : "string" 
         }
      }
   ],
   "nextToken": "string"
}
```

## Response Elements
<a name="API_ListChannelNamespaces_ResponseElements"></a>

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [channelNamespaces](#API_ListChannelNamespaces_ResponseSyntax) **   <a name="appsync-ListChannelNamespaces-response-channelNamespaces"></a>
The `ChannelNamespace` objects.  
Type: Array of [ChannelNamespace](API_ChannelNamespace.md) objects

 ** [nextToken](#API_ListChannelNamespaces_ResponseSyntax) **   <a name="appsync-ListChannelNamespaces-response-nextToken"></a>
An identifier that was returned from the previous call to this operation, which you can use to return the next set of items in the list.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 65536.  
Pattern: `[\S]+` 

## Errors
<a name="API_ListChannelNamespaces_Errors"></a>

For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** BadRequestException **   
The request is not well formed. For example, a value is invalid or a required field is missing. Check the field values, and then try again.    
 ** detail **   
Provides further details for the reason behind the bad request. For reason type `CODE_ERROR`, the detail will contain a list of code errors.  
 ** reason **   
Provides context for the cause of the bad request. The only supported value is `CODE_ERROR`.
HTTP Status Code: 400

 ** InternalFailureException **   
An internal AWS AppSync error occurred. Try your request again.  
HTTP Status Code: 500

 ** NotFoundException **   
The resource specified in the request was not found. Check the resource, and then try again.  
HTTP Status Code: 404

 ** UnauthorizedException **   
You aren't authorized to perform this operation.  
HTTP Status Code: 401

## See Also
<a name="API_ListChannelNamespaces_SeeAlso"></a>

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/appsync-2017-07-25/ListChannelNamespaces) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/appsync-2017-07-25/ListChannelNamespaces)