Error while uploading a file with gzipped content via HTTP POST - jmeter

Question

I am trying to upload a file using HTTP POST sampler, at the same time compressing the file content. For this, I have added Content-Encoding:gzip in the Header Manager and in the pre processor of the sampler added following code
import org.apache.commons.io.IOUtils;
import java.util.zip.GZIPOutputStream;
String bodyString = sampler.getArguments().getArgument(0).getValue();
byte [] requestBody = bodyString.getBytes();
ByteArrayOutputStream out = new ByteArrayOutputStream(requestBody.length);
GZIPOutputStream gzip = new GZIPOutputStream(out);
gzip.write(requestBody);
gzip.close();
sampler.getArguments().getArgument(0).setValue(out.toString(0));
This was not working and it was throwing following exception
2019-08-07 14:08:21,970 ERROR o.a.j.m.JSR223PreProcessor: Problem in JSR223 script, JSR223 PreProcessor
javax.script.ScriptException: Sourced file: inline evaluation of: ``import org.apache.commons.io.IOUtils; import java.util.zip.GZIPOutputStream; S . . . '' : Typed variable declaration : at Line: 5 : in file: inline evaluation of: ``import org.apache.commons.io.IOUtils; import java.util.zip.GZIPOutputStream; S . . . '' : .getValue ( )
Target exception: java.lang.NullPointerException: Attempt to invoke method getValue on null value
in inline evaluation of: ``import org.apache.commons.io.IOUtils; import java.util.zip.GZIPOutputStream; S . . . '' at line number 5
at bsh.engine.BshScriptEngine.evalSource(BshScriptEngine.java:87) ~[bsh-2.0b6.jar:2.0b6 2016-02-05 05:16:19]
at bsh.engine.BshScriptEngine.eval(BshScriptEngine.java:46) ~[bsh-2.0b6.jar:2.0b6 2016-02-05 05:16:19]
at javax.script.AbstractScriptEngine.eval(Unknown Source) ~[?:1.8.0_73]
at org.apache.jmeter.util.JSR223TestElement.processFileOrScript(JSR223TestElement.java:225) ~[ApacheJMeter_core.jar:5.1.1 r1855137]
at org.apache.jmeter.modifiers.JSR223PreProcessor.process(JSR223PreProcessor.java:44) [ApacheJMeter_components.jar:5.1.1 r1855137]
at org.apache.jmeter.threads.JMeterThread.runPreProcessors(JMeterThread.java:935) [ApacheJMeter_core.jar:5.1.1 r1855137]
at org.apache.jmeter.threads.JMeterThread.executeSamplePackage(JMeterThread.java:537) [ApacheJMeter_core.jar:5.1.1 r1855137]
at org.apache.jmeter.threads.JMeterThread.processSampler(JMeterThread.java:486) [ApacheJMeter_core.jar:5.1.1 r1855137]
at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:253) [ApacheJMeter_core.jar:5.1.1 r1855137]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_73]
Now to debug added log.info("sampler-------:"+sampler) before getValue like
log.info("sampler-------:"+sampler);
String bodyString = sampler.getArguments().getArgument(0).getValue();
But in the logs sampler returned empty
Query Data:
So how should I access the file content in the HTTP Request and at the same time gzip it and send?

Answer 1

To gzip the file and its contents use the following code and put it in JSR223 Sampler [this should be before calling POST API] and the assumption is payload data is already copied to a file.
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;
String source_filepath = "C:/Sample/Input.txt";
String destinaton_zip_filepath = "C:/Sample/Input.gzip";
byte[] buffer = new byte[1024];
try {
FileOutputStream fileOutputStream =new FileOutputStream(destinaton_zip_filepath);
GZIPOutputStream gzipOuputStream = new GZIPOutputStream(fileOutputStream);
FileInputStream fileInput = new FileInputStream(source_filepath);
int bytes_read;
while ((bytes_read = fileInput.read(buffer)) > 0) {
gzipOuputStream.write(buffer, 0, bytes_read);
}
fileInput.close();
gzipOuputStream.finish();
gzipOuputStream.close();
} catch (IOException ex) {
ex.printStackTrace();
}
vars.put("ZipFileLocation",destinaton_zip_filepath);
Now the gzip file can be used via ${ZipFileLocation} variable.
It is up to how the API is called, following can be the solution:
Directly send this gzip file in the API
Declare a variable and hold all your payload data into it and then call the API -> gzip it
Note : Correct MIME type and Headers need to be used wherever applicable

Answer 2

If you're doing a file upload with JMeter, to wit your file is being passed via "Files Upload" section - you will not be able to get anything using getArguments() function, you will need to use getHTTPFiles() instead, suggested algorithm:
Get the required file path like:
def plainFile = sampler.getHTTPFiles()[0].path
Compress the file according to your server expectations
Replace the original file path with compressed file path
sampler.getHTTPFiles()[0].setPath("/path/to/compressed/file.gz")