mule download all files from s3 bucket - mule

Question

<flow name="listobjects">
<http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" path="listobjects" contentType="text/plain" doc:name="HTTP"/>
<s3:list-objects config-ref="Amazon_S3" bucketName="demo" doc:name="Amazon S3" maxKeys="5" />
<!-- <payload-type-filter expectedType="java.util.List" doc:name="Payload"/> -->
<foreach collection="#[payload]" doc:name="For Each">
<!-- <foreach doc:name="For Each file"> -->
<logger message=" inside foreach...... #[payload.getKey()] ...." level="INFO" doc:name="Logger" />
<s3:get-object-content config-ref="Amazon_S3" bucketName="demo" key="#[payload.getKey()]" doc:name="Amazon S3"/>
<object-to-byte-array-transformer/>
<file:outbound-endpoint path="C:\output" responseTimeout="10000" doc:name="File" outputPattern="#[payload.getKey()] "></file:outbound-endpoint>
</foreach>
</flow>
I have bucket name called demo.
In that bucket I have 3 pdf files. I want to download all files and put it in c:\output folder.
I hit my url like http://localhost:8081/listobjects.
But I got the error:
Could not find a transformer to transform "CollectionDataType{type=org.mule.module.s3.simpleapi.SimpleAmazonS3AmazonDevKitImpl$S3ObjectSummaryIterable, itemType=com.amazonaws.services.s3.model.S3ObjectSummary, mimeType='/'}" to "SimpleDataType{type=org.mule.api.transport.OutputHandler, mimeType='/'}". (org.mule.api.transformer.TransformerException) (org.mule.api.transformer.TransformerException). Message payload is of type: SimpleAmazonS3AmazonDevKitImpl$S3ObjectSummaryIterable

Answer 1

The error occurs because after the foreach processor the payload is an instance of an S3 class, and you haven't specified any Content-Type to return. So Mule tries to transform the S3 instance to the default SimpleDataType and fails.
One way to solve it is simply to add something like
<set-property propertyName="Content-Type" value="application/json" doc:name="Content-Type" />
<set-payload value="{'result': 'ok'}"/>
at the end to make it explicit.
Also note that in your flow after running:
<object-to-byte-array-transformer/>
the S3 payload is gone, so #[payload.getKey()] will fail in the next processor:
<file:outbound-endpoint path="C:\output" responseTimeout="10000" doc:name="File" outputPattern="#[payload.getKey()] "></file:outbound-endpoint>
I've run this without problems:
<flow name="listobjects">
<http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8083" path="listobjects" contentType="text/plain" doc:name="HTTP"/>
<s3:list-objects config-ref="Amazon_S3" bucketName="mule_test" doc:name="Amazon S3" maxKeys="5" />
<foreach collection="#[payload]" doc:name="For Each">
<logger message=" inside foreach...... #[payload.getKey()] ...." level="INFO" doc:name="Logger" />
<set-variable variableName="fileKey" value="#[payload.getKey()]" doc:name="Variable" />
<s3:get-object-content config-ref="Amazon_S3" bucketName="#[payload.getBucketName()]" key="#[payload.getKey()]" doc:name="Amazon S3"/>
<object-to-byte-array-transformer/>
<file:outbound-endpoint path="/tmp" responseTimeout="10000" doc:name="File" outputPattern="#[flowVars.fileKey] "></file:outbound-endpoint>
</foreach>
<set-property propertyName="Content-Type" value="application/json" doc:name="Content-Type" />
<set-payload value="{'result': 'ok'}"/>
</flow>