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The quickest way to "test out" a PJS module to see how things work is to create it as a Express Route (web service), and call it using a browser.

Example 1

In the following example, we'll create a web service to pass in a customer number = 1234, and get back the customer name  for that customer number.

  • Navigate to the workspace "pjstips".
  • Click New/Javascript File.
  • Enter the code below. Click Save As, and save as pjstips_02_1.js.
  • function app(req, res) {
  
  // When a PJS module is called as an Express Route (web service), two objects
  // are passed to the module.
  // 1. The "request" object, named as "req" here. You can use another name if you want.
  // 2. The "reponse" object, named as "res" here. You can use another name if you want.

  // Put this module in debug and call it from a browser. Then examine the "req" and "res" objects passed in, 
  // to see all the good stuff they contain.

  var custno = req.query.custno;          // input parm specified as query string paratemer, e.g. ?custno=1234
  var name = `Customer_name_${custno}`;   // get output customer name from input customer number

  // In this example, we'll use function res.send() to send back the "response" as a text message.
  
  res.send(`test from pjstips_02_1.js; custno = ${custno}; name = ${name}`);

}

exports.run = app;
  • In the Files tree, right-click on newly-created file pjstips_02_1.js, and click Properties. Mark the file as an Express Route, using HTTP method of "GET", with the Route Path as shown below.

  • Now, you can "call" that PJS module as a web service from a browser, using the URL http://localhost:8081/run/pjstips/pjstips_02_1 . The format of the URL is http://host:port/run/<Route Path>, where <Route Path> is as shown in the picture above.
  • If you want to pass parameters to the PJS module from the browser, you can use query string parameters, in the format of :
    • <yourURL>?parm1=value1&parm2=value2
  • For example, use this URL http://localhost:8081/run/pjstips/pjstips_02_1?custno=1234 to pass a parm of "custno" with value of "1234" to the PJS module.
  • To debug the module pjstips_02_1.js, put itin debug using your favorite debug tool (e.g. VS Code or Chrome), add a breakpoint, then call it from a browser.


Example 2

The previous example sends back the "response" as a text message. In the next example, we'll send back the reponse as JSON.

  • Click New/Javascript File.
  • Enter the code below. Click Save As, and save as pjstips_02_2.js.
  • function app(req, res) {
  
  // When a PJS module is called as an Express Route (web service), two objects
  // are passed to the module.
  // 1. The "request" object, named as "req" here. You can use another name if you want.
  // 2. The "reponse" object, named as "res" here. You can use another name if you want.

  // Put this module in debug and call it from a browser. Then examine the "req" and "res" objects passed in, 
  // to see all the good stuff they contain.

  var custno = req.query.custno;          // input parm specified as query string paratemer, e.g. ?custno=1234
  var name = `Customer_name_${custno}`;   // get output customer name from input customer number

  // In this example. we'll use function res.json() to send back the "response" as a JSON object
  var data = 					// format the "response" as a JSON object like this
  {
    "custno": custno,
    "name"  : name
  };

  res.json(data);

}

exports.run = app;
  • In the Files tree, right-click on newly-created file pjstips_02_2.js, and click Properties. Mark the file as an Express Route, using HTTP method of "GET", with the Route Path as shown below.
  • Now, the URL to call this PJS module is http://localhost:8081/run/pjstips/pjstips_02_2?custno=1234 .
  • You should see the response on as JSON as shown below on the browser.


Example 3

In the next example, we'll create a web service that's supposed to be called as a POST request, with a "body" that contains input parameters as a JSON object , instead of a GET request with input parms specified as query string parameters.

  • Click New/Javascript File.
  • Enter the code below. Click Save As, and save as pjstips_02_3.js.
  • function app(req, res) {
  
  // When a PJS module is called as an Express Route (web service), two objects
  // are passed to the module.
  // 1. The "request" object, named as "req" here. You can use another name if you want.
  // 2. The "reponsse" object, named as "res" here. You can use another name if you want.

  // Put this module in debug and call it from a browser. Then examine the "req" and "res" objects passed in, 
  // to see all the good stuff they contain.

  var custno = req.body.custno;           // input parm specified in the "body" of the POST request
  var name = `Customer_name_${custno}`;   // get output customer name from input customer number

  // In this example. we'll use the function res.json() to send back the "response" as a JSON object
  var data = 
  {
    "custno": custno,
    "name"  : name
  };

  res.json(data);

}

exports.run = app;
  • In the Files tree, right-click on newly-created file pjstips_02_3.js, and click Properties. Mark the file as an Express Route, using HTTP method of "GET", with the Route Path as shown below.
  • Now, the URL to call this PJS module is http://localhost:8081/run/pjstips/pjstips_02_03. Note that you can NOT simple put this URL on a browser to "call" the module. You'd need to use some tool (e.g. POSTMAN or PJS low-code module or PAPI) to send a POST request, with the input parms specified in the "body" of the request. We'll use this web service in the tips related to using low-code modules that consume a REST web service.



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