API Gateway Integration with S3 || Problem in setting Path Parameter

Question

Problem statement:

I am working on integrating S3 bucket with API Gateway to put objects in S3. 
The set-up i have:

I have created the {proxy+} to create folder like structure in s3. 
In Integration Request setting i have configured AWS Region, AWS Service (S3), Http Method (PUT), **Action Type**: Use path override
**Path override** : {bucket}/{object} 
Execution role: arn:aws:iam::12345667987:role/api-gateway-upload-to-s3

I am facing the challenge in mapping the {object} value. I know i can map it directly using **URL Path Parameter**  setting. But the problem is I'll have to compute this value using method.request.path.param and method.request.header.param . for instance, my path parameter is "/v1/document/12345678987/page" and my request header is Filename : Samplefile.txt. So, after computation my {object} value should look like this  **/v1/document/12345678987/page/Samplefile.txt**.

Is there a way to achieve this using either **URL Path Parameter** or Mapping Templates ??

I am trying to achieve this using mapping template:

```
#set($path = "$input.params('objectkey')")  # Extract DocumentId from path
#set($resourceName = "$input.headers('Filename')")  # Extract header parameter

#set($computedObjectName = "$path/$resourceName")  # Concatenate the object name

{
  "bucket": "s2notificationeventtriggerlambdafunction",
  "key": "$computedObjectName"
}
```

re:Post Agent · Answer

Yes, you can achieve this using a mapping template in the Integration Request settings of your API Gateway. Your approach is on the right track, but needs a few adjustments to work correctly.

Here's an improved version of the mapping template that should solve your problem:

```
#set($path = $input.params().path.get('proxy'))
#set($filename = $input.params().header.get('Filename'))
#set($computedObjectName = "$path/$filename")

{
    "bucket": "s2notificationeventtriggerlambdafunction",
    "key": "$computedObjectName"
}
```

This template does the following:

1. It extracts the full path from the 'proxy' parameter, which in your case would be "v1/document/12345678987/page".
2. It gets the filename from the 'Filename' header.
3. It combines these two to create the computed object name.

To use this template:

1. In the Integration Request settings, set the "Content-Type" header to "application/json".
2. In the "Mapping Templates" section, add a mapping for "application/json" content-type and paste the above template.

This approach allows you to compute the object key dynamically based on both the path parameters and the header, which meets your requirement of having the final object key as "/v1/document/12345678987/page/Samplefile.txt".

Remember to ensure that your IAM role (api-gateway-upload-to-s3) has the necessary permissions to put objects in the specified S3 bucket.

Also, make sure your API method is configured to receive the 'Filename' header, and that your client is sending this header with the request.

This solution provides flexibility and allows you to construct complex object keys based on various inputs from the API request.  
**Sources**  
[Integration - Amazon API Gateway](https://docs.aws.amazon.com/apigateway/latest/api/API_Integration.html)  
[Basic tasks of an API integration request - Amazon API Gateway](https://docs.aws.amazon.com/apigateway/latest/developerguide/integration-request-basic-setup.html)  
[PutIntegration - Amazon API Gateway](https://docs.aws.amazon.com/apigateway/latest/api/API_PutIntegration.html)  
[x-amazon-apigateway-integration.requestParameters object - Amazon API Gateway](https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-swagger-extensions-integration-requestParameters.html)  
[Tutorial: Create a REST API as an Amazon S3 proxy - Amazon API Gateway](https://docs.aws.amazon.com/apigateway/latest/developerguide/integrating-api-with-aws-services-s3.html)

API Gateway Integration with S3 || Problem in setting Path Parameter

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