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Example of a low-code module with a bug

• Navigate to the workspace "pjstips".
• Click New/Module File.

• Click Edit/Source, to bring up the Source view.

• Clear the current default code, and enter the code below.

• 
  

  Code Block
  language js title pjstips_04_1.module.json
  { "routines": [ { "name": "routine1", "inputs": [ { "type": "decimal", "ibmiLength": 4, "name": "custno", "ibmiDecimals": 0 } ], "outputs": [ { "type": "string", "ibmiLength": 30, "name": "name" } ], "steps": [ { "text": "Consume REST service", "answers": { "plugin": "Custom:web-service", "uri": "http://localhost:8081/run/pjstips/pjstips_02_3", "method": "POST", "headers": "{\"Content-Type\": \"application/x-www-form-urlencoded\"}", "body": "{\n \"custno\": input[\"custno\"]\n}", "json": true, "auth": "", "capture_response": true, "capture_on_error": false, "capture_as": "Value", "specific_property": "", "destination": "Work variable", "work_variable": "myres" } }, { "text": "Set Module output", "answers": { "plugin": "Program Data:set-module-output", "module-output-values": { "name": "myres[\"name\"]" } } } ] } ] }

  
  

• Click Edit/Design, to bring up the Design view.
• If needed, in the "Consume REST service" step, change the Endpoint URL to point to the correct host/port.
• Click Home/Save As, and save as pjstips_04_1.module.json.
• You've created a low-code module, as shown below, with a routine named "routine1" that:
  
  • Takes an input parameter of "custno".
  • Uses plug "Consume REST service" to issue a POST request to URL http://localhost:8081/run/pjstips/pjstips_02_3 (created in a previous example).
  • The input "custno" is specified in the "body" of the POST request.
  • The returned JSON object from the REST web service is saved in a work variable named "myres".
  • The value of myres["name"] is used to set the output value output["name"].
  • But, it has a bug; we'll learn how to debug this problem.
  • 

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• Below is an example, there the input custno is set to 1234 to pass to the low-code module, which calls the REST service to get the customer name, which is then returned to the RPG program, which is then displayed on the screen.

**free

  Dcl-PR PJSCALL ExtPgm;
    ParmType        Char(30)          Const;
    ModuleID        VarUCS2(500)      Const;
    RoutineName     VarUCS2(70)       Const;
    InputParms      Char(16773104)    Const Options(*Varsize:*Omit:*NoPass);
    InputParmSize   Int(10)           Const Options(*Omit:*NoPass);
    OutputParms     Char(16773104)    Options(*Varsize:*Omit:*NoPass);
    OutputParmSize  Int(10)           Const Options(*Omit:*NoPass);
  End-PR;

  Dcl-DS InputDS Qualified Inz;
    custno  Zoned(4: 0);
  End-DS;

  Dcl-DS OutputDS Qualified Inz;
    name  VarChar(30);
  End-DS;

  InputDS.custno = 1234;			// pass input to the low-code module in "InputDS"

  Monitor;

    PJSCALL('*MODULE'
      : 'pjstips:pjstips_04_1.module.json'
      : 'routine1'
      : InputDS
      : %Size(InputDS)
      : OutputDS
      : %Size(OutputDS)
    );

  On-Error;


  EndMon;

  dsply  OutputDS.name;				// output from the low-code module in "OutputDS"		
  *inlr = *on;
  return;

...

If you want to debug that low-code module, you can do go through the follow following steps to "convert" it into "real" PJS code and call it as an Express Route (web service). This is also a good way to learn how things are done behide behind the scenescenes. When a low-code module is called, the JSON file is "transformed" into "real" PJS code, and the then that "transformed" module is run.

• 1. On the PJS IDE, on code panel (upper center panel), in the top-left cordercorner, click the </> button to "transform" the low-code steps into real PJS code.

...

• 2. On the popup message below, click OK.

• 3. VERY IMPORTANT! You can convert from low-code to real code only, not the other way! You can NOT go back! That is, you can NOT convert from real code back to low-code. So, after you see the real code show up on the next step, do NOT save the module file, if you want to keep it as low-code.
• 4. The "real" PJS code is shown below:

• 5. Copy/paste that code to somewhere (e.g. Notepad++) and save it.
• 6. Close the file. Do NOT save it! If you save it, your module now will contain real code, not low-code anymore.
• 7. Now, create a new web service with the code saved in step (5) above, with some minor adjustments, so that you can call it from a browser and debug it. Refer to As a general reference, click here to see how to create a web service. Follow the steps below to create a web service for this example.
• 8. Click New/Javascript file.
• 9. Enter the code below. This is pretty much the same as the code you saved in step (5) above, but changed so that it can be called as a web service from the browser, so you can debug it easily.

function app(req, res) {
  
  // init these 2 objects that would normally be done when a low-code module is called
  var input = {};
  var output = {};

  // set input data
  input.custno = 1234;

  // start of code converted from low-code module low-code module in step (5) above --------------------------
  // Consume REST service
  var _data = pjs.sendRequesthttpRequest({
    method: "POST",
    uri: `http://localhost:8081/run/pjstips/pjstips_02_3`,
    headers: {"Content-Type": "application/x-www-form-urlencoded"},
    body: {
    "custno": input["custno"]
    },
    json: true
  });
  var myres = _data;

  // Set Module output
  output["name"] = myres["name"];
  // end of code converted from low-code module in step (5) above ----------------------------
  
  // send back "output" from low-code module as JSON
  res.json(output);

}

exports.run = app;

...

You'll get the same error as before. But now, you can debug it, and find out where the problem is. Is it due to the way you answered the low-code questions?  Is it due to a bug in one of the PJS functions? Is due to the way you answered , even though you've answered all the low-code questions properly? In this example, if you step through the code in debug, you'll see that the error occurs on the call to PJS API pjs.sendRequest(). The problem here is that the "body" of the POST request is sent as JSON, but the "headers" says that the content type is ""application/x-www-form-urlencoded", so the API pjs.sendRequest() fails. To fix that, you can comment out the "headers" in this code, and test it to verify that it works here.

After the "headers" line is commented out in this code, the call to URL http://localhost:8081/run/pjstips/pjstips_04_2 works, and JSON object "data" is returned to the browser as shown below.

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