How to upload zip file through REST API Mule 4?

Question

I'm trying to upload zip file to the url https://anypoint.mulesoft.com/designcenter/api-designer/projects/{projectId}/branches/master/import. Content-Type must be application/zip, cant change to multipart/form-data. In Mule 3, a java transform class is used (com.test.FileReader) with the FileReader.class is stored in lib. It worked in Mule 3. I tried to use ReadFile component to read test.zip and set as payload but it's not working. Any suggestion how to upload zip file in Mule 4?

package com.test;
 
import org.mule.transformer.*;
import org.mule.api.*;
import org.mule.api.transformer.*;
import java.io.*;
 
public class PayloadFileReader extends AbstractMessageTransformer
{
    public Object transformMessage(final MuleMessage message, final String outputEncoding) throws TransformerException {
        byte[] result = null;
        try {
            result = this.readZipFile("test.zip");
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        message.setPayload((Object)result);
        return message;
    }
    
    public String readFileTest(final String path) throws FileNotFoundException, IOException, Exception {
        final ClassLoader classLoader = this.getClass().getClassLoader();
        final File file = new File(classLoader.getResource(path).getFile());
        final FileReader fileReader = new FileReader(file);
        BufferedReader bufferReader = null;
        final StringBuilder stringBuffer = new StringBuilder();
        try {
            bufferReader = new BufferedReader(fileReader);
            String line;
            while ((line = bufferReader.readLine()) != null) {
                stringBuffer.append(line);
            }
        }
        catch (IOException e) {
            e.printStackTrace();
            if (bufferReader != null) {
                try {
                    bufferReader.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        finally {
            if (bufferReader != null) {
                try {
                    bufferReader.close();
                }
                catch (IOException e2) {
                    e2.printStackTrace();
                }
            }
        }
        return stringBuffer.toString();
    }
    
    public byte[] readZipFile(final String path) {
        final ClassLoader classLoader = this.getClass().getClassLoader();
        final File file = new File(classLoader.getResource(path).getFile());
        final byte[] b = new byte[(int)file.length()];
        try {
            final FileInputStream fileInputStream = new FileInputStream(file);
            fileInputStream.read(b);
            fileInputStream.close();
        }
        catch (FileNotFoundException e) {
            System.out.println("Not Found.");
            e.printStackTrace();
        }
        catch (IOException e2) {
            System.out.println("Error");
            e2.printStackTrace();
        }
        return b;
    }
}

'

Answer 1

You can't use Java code that depends on Mule 3 classes in Mule 4. Don't bother trying to adapt the code, it is not meant to work. Their architecture are just different.

While in Mule 4 you can use plain Java code or create a module with the SDK, there is no reason to do so for this problem and it would be counterproductive. My advise it to forget the Java code and resolve the problem with pure Mule 4 components.

In this case there doesn't seem a need to actually use Java code. The File connector read operation should read the file just fine as it doesn't appear the Java code is doing anything else than reading the file into the payload.

Sending through the HTTP Request connector should be straightforward. You didn't provide any details of the error, (where is it happening, complete error message, HTTP status error code, complete flow with the HTTP request in both versions, etc) and the API Designer REST API doesn't document an import endpoint so it is difficult to say if the request is correctly constructed.

Answer 2

Assuming that your zip file corresponds to a valid API spec, in Mule 4, you don't need to use a custom java code to achieve what you want: you can read the file content using the File connector Read operation, and use an HTTP Request to upload it to Design Center using Design Center API. Your flow should look like:

For the Read operation, you only need to set the file location, in the File Path operation property.

No need to set content type in the HTTP Request (Mule 4 will configure the content type automatically based on the file content loaded by the Read operation).