# CreateFunction
<a name="API_CreateFunction"></a>

Creates a `Function` object.

A function is a reusable entity. You can use multiple functions to compose the resolver logic.

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

```
POST /v1/apis/apiId/functions HTTP/1.1
Content-type: application/json

{
   "code": "string",
   "dataSourceName": "string",
   "description": "string",
   "functionVersion": "string",
   "maxBatchSize": number,
   "name": "string",
   "requestMappingTemplate": "string",
   "responseMappingTemplate": "string",
   "runtime": { 
      "name": "string",
      "runtimeVersion": "string"
   },
   "syncConfig": { 
      "conflictDetection": "string",
      "conflictHandler": "string",
      "lambdaConflictHandlerConfig": { 
         "lambdaConflictHandlerArn": "string"
      }
   }
}
```

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

The request uses the following URI parameters.

 ** [apiId](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-uri-apiId"></a>
The GraphQL API ID.  
Required: Yes

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

The request accepts the following data in JSON format.

 ** [code](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-code"></a>
The `function` code that contains the request and response functions. When code is used, the `runtime` is required. The `runtime` value must be `APPSYNC_JS`.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 32768.  
Required: No

 ** [dataSourceName](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-dataSourceName"></a>
The `Function` `DataSource` name.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 65536.  
Pattern: `[_A-Za-z][_0-9A-Za-z]*`   
Required: Yes

 ** [description](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-description"></a>
The `Function` description.  
Type: String  
Required: No

 ** [functionVersion](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-functionVersion"></a>
The `version` of the request mapping template. Currently, the supported value is 2018-05-29. Note that when using VTL and mapping templates, the `functionVersion` is required.  
Type: String  
Required: No

 ** [maxBatchSize](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-maxBatchSize"></a>
The maximum batching size for a resolver.  
Type: Integer  
Valid Range: Minimum value of 0. Maximum value of 2000.  
Required: No

 ** [name](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-name"></a>
The `Function` name. The function name does not have to be unique.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 65536.  
Pattern: `[_A-Za-z][_0-9A-Za-z]*`   
Required: Yes

 ** [requestMappingTemplate](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-requestMappingTemplate"></a>
The `Function` request mapping template. Functions support only the 2018-05-29 version of the request mapping template.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 65536.  
Pattern: `^.*$`   
Required: No

 ** [responseMappingTemplate](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-responseMappingTemplate"></a>
The `Function` response mapping template.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 65536.  
Pattern: `^.*$`   
Required: No

 ** [runtime](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-runtime"></a>
Describes a runtime used by an AWS AppSync pipeline resolver or AWS AppSync function. Specifies the name and version of the runtime to use. Note that if a runtime is specified, code must also be specified.  
Type: [AppSyncRuntime](API_AppSyncRuntime.md) object  
Required: No

 ** [syncConfig](#API_CreateFunction_RequestSyntax) **   <a name="appsync-CreateFunction-request-syncConfig"></a>
Describes a Sync configuration for a resolver.  
Specifies which Conflict Detection strategy and Resolution strategy to use when the resolver is invoked.  
Type: [SyncConfig](API_SyncConfig.md) object  
Required: No

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

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

{
   "functionConfiguration": { 
      "code": "string",
      "dataSourceName": "string",
      "description": "string",
      "functionArn": "string",
      "functionId": "string",
      "functionVersion": "string",
      "maxBatchSize": number,
      "name": "string",
      "requestMappingTemplate": "string",
      "responseMappingTemplate": "string",
      "runtime": { 
         "name": "string",
         "runtimeVersion": "string"
      },
      "syncConfig": { 
         "conflictDetection": "string",
         "conflictHandler": "string",
         "lambdaConflictHandlerConfig": { 
            "lambdaConflictHandlerArn": "string"
         }
      }
   }
}
```

## Response Elements
<a name="API_CreateFunction_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.

 ** [functionConfiguration](#API_CreateFunction_ResponseSyntax) **   <a name="appsync-CreateFunction-response-functionConfiguration"></a>
The `Function` object.  
Type: [FunctionConfiguration](API_FunctionConfiguration.md) object

## Errors
<a name="API_CreateFunction_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

 ** ConcurrentModificationException **   
Another modification is in progress at this time and it must complete before you can make your change.  
HTTP Status Code: 409

 ** 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_CreateFunction_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/CreateFunction) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/appsync-2017-07-25/CreateFunction) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/appsync-2017-07-25/CreateFunction)