CREATE JAVA ACTION: AS $$ block generates uncompilable Java (imports in method body)

[engalar]

Problem

CREATE JAVA ACTION ... AS $$ ... $$ generates Java files that fail to compile, because the $$ code is placed verbatim into the executeAction() method body (BEGIN USER CODE region) without handling imports.

Per Mendix official docs:

Only the following code will be retained when actions are regenerated:

• the import list
• the code between BEGIN USER CODE and END USER CODE
• the code between BEGIN EXTRA CODE and END EXTRA CODE

Imports are a separate preserved region at file top level, but mxcli has no mechanism to populate it.

Reproduction

CREATE JAVA ACTION MyModule.ReadCSV(File: System.FileDocument) RETURNS String
AS $$
IContext context = this.getContext();
InputStream is = Core.getFileDocumentContent(context, File.getMendixObject());
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
String line = reader.readLine();
reader.close();
return line;
$$;

Generated Java file only has default imports:

import com.mendix.systemwideinterfaces.core.IContext;
import com.mendix.systemwideinterfaces.core.UserAction;
import com.mendix.systemwideinterfaces.core.IMendixObject;

Core, InputStream, BufferedReader, InputStreamReader are all unresolved → compilation error.

What happens when AI agents write the code

AI agents naturally prepend import statements inside $$:

AS $$
import com.mendix.core.Core;
import java.io.*;
// actual code...
$$;

These end up inside the method body, which is illegal Java:

public String executeAction() throws Exception {
    // BEGIN USER CODE
    import com.mendix.core.Core;     // ← syntax error
    import java.io.*;                 // ← syntax error
    // ...
}

This happened to all 3 Java Actions in our project (CreateOrdersFromCSV, ParseCSVFile, ReadResourceFile).

Root cause

AS $$ only writes to BEGIN USER CODE. The generated .java file has no mechanism to receive additional imports.

Suggested fixes

Option A: Strip import lines from $$ and move to file header (minimal, backward-compatible)

If $$ block contains lines matching ^\s*import\s+[\w.*]+;\s*$, extract them and place in the import section instead of the method body. This makes AI-generated code "just work".

Option B: Add IMPORT clause to MDL syntax

CREATE JAVA ACTION MyModule.ReadCSV(File: System.FileDocument) RETURNS String
IMPORT com.mendix.core.Core, java.io.*, java.util.*
AS $$
// can use short names
$$;

Option C: Auto-detect types and inject imports

Scan $$ code for known type references and auto-add imports. A reasonable default mapping:

Type	Import
Core	com.mendix.core.Core
IContext	com.mendix.systemwideinterfaces.core.IContext
IMendixObject	com.mendix.systemwideinterfaces.core.IMendixObject
IMendixIdentifier	com.mendix.systemwideinterfaces.core.IMendixIdentifier
InputStream	java.io.InputStream
BufferedReader	java.io.BufferedReader
InputStreamReader	java.io.InputStreamReader
BigDecimal	java.math.BigDecimal
List, ArrayList	java.util.List, java.util.ArrayList
Map, HashMap	java.util.Map, java.util.HashMap
ILogNode	com.mendix.logging.ILogNode

Bonus: Support BEGIN EXTRA CODE

Consider an EXTRA $$...$$ block for helper methods:

CREATE JAVA ACTION MyModule.MyAction() RETURNS String
AS $$
return helper();
$$
EXTRA $$
private String helper() { return "ok"; }
$$;

Also: skill doc java-actions.md references removed API

The Core API Reference table in java-actions.md lists:

Core.retrieveXPathQuery(context, xpath)

This method does not exist in Mendix 10+/11. The correct API per official docs is:

Core.createXPathQuery(xpath).execute(context)

This causes AI agents to generate code that compiles but fails with method not found.

Environment

• mxcli: 0.1.0
• Mendix: 11.6.4
• Platform: Windows 11

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Copied from engalar#44

[github-actions]

Issue Triage

Summary:
The issue reports that CREATE JAVA ACTION … AS $$ places import statements inside the method body, causing compilation errors because mxcli does not extract imports to the file’s import section.

Checklist of required bug‑report information

Required info	Present?	Notes
mxcli version	✅	mxcli: 0.1.0
Mendix version	✅	Mendix: 11.6.4
Scenario (what the user was trying to do)	✅	MDL script with CREATE JAVA ACTION … AS $$
Expected output	✅	Imports should be moved to the file header so the generated Java compiles
Experienced output	✅	Imports stay inside the method body → syntax errors and unresolved types
AI bug report (output of mxcli diag --bundle or session log)	❌	Not provided

What’s missing:
To help us diagnose the problem, could you please run mxcli diag --bundle (or at least share the session log) and attach the output? This will give us insight into the CLI’s internal state when the issue occurs.

Thank you for the detailed report! Once we have the diagnostic information, we can investigate further.

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