JSON Decoding Examples

This section needs work. It is not complete.

Simple REST JSON Post - Example 1

First we will look at a simple REST JSON Post. The screenshot below has the service operation setup. This is the most simple web service. You will notice that:

There is no Template other than /
There is no Document Template because we are not passing any parameters
The Request and Response Message objects are both CHG_GENERIC.V1 which is a “Nonrowset-based” based messages. This is is not shown.

We plan on posting some simple JSON to this. The HTTP Signature will look like this:

POST http://localhost:8000/PSIGW/RESTListeningConnector/PSFT_CS/CHG_JSON_TEST.v1/
Authorization: Basic UFM6dHJ5aW5nLXNlZS1pZi1JLXBvc3RlZC1teS1wYXNzd29yZC1JLXNlZQ==
Content-Type: application/json

{
   "firstName": "Chris",
   "lastName": "Malek",
   "Region": "Southern California",
   "FavoriteDesert": "Pie, any kind"
}

The response that comes out of this web services the following.

HTTP/1.1 200 OK
Connection: close
Date: Wed, 02 Dec 2020 04:33:21 GMT
Content-Length: 234
Content-Type: application/json; encoding="UTF-8"
Content-Encoding: gzip
Set-Cookie: JSESSIONID=6zshuetDLvmVT5G55VCUt0su3nVWAn469hsagTQOqg0zHVExziNa!-1985259815; path=/; HttpOnly,psmap=; domain=.c.peoplesoftdemo-1470578694381.internal; path=/

{

  "firstName": "Chris",
  "lastName": "Malek",
  "Region": "Southern California",
  "FavoriteDesert": "Pie, any kind",
  "META": {

    "OPRID": "PS",
    "CURRENT_TIME": "2020-12-02 04:33:21.000000",
    "TRANSACTION_ID": "81fa5f4b-3457-11eb-9b6b-e783fa52141b",
    "DBNAME": "CS92U009"
  }
}

The handler parses the inbound root JSON object strings and echos any value back out. We also add a “META” object with some information about the run-time environment.

The entire PeopleCode handler for this web service is:

import PS_PT:Integration:IRequestHandler;

class simpleJSONPost implements PS_PT:Integration:IRequestHandler
   method onRequest(&msRequest As Message) Returns Message;

end-class;

method onRequest
   /+ &msRequest as Message +/
   /+ Returns Message +/
   /+ Extends/implements PS_PT:Integration:IRequestHandler.OnRequest +/


   Local Message &response = CreateMessage(@("Operation." | &msRequest.OperationName), %IntBroker_Response);

   Local JsonObject &responseRootJSON = CreateJsonObject();

   Local string &requestPayload = &msRequest.GetContentString();

   Local JsonParser &parser = CreateJsonParser();

   Local boolean &bParseResult = &parser.Parse(&requestPayload);

   If &bParseResult = True Then
      Local integer &i;

      Local JsonObject &jObj = &parser.GetRootObject();
      For &i = 1 To &jObj.ChildCount

         Local string &propName;

         &propName = &jObj.GetPropertyNameAt(&i);
         &responseRootJSON.AddProperty(&propName, &jObj.GetAsString(&propName));

      End-For;
   End-If;


   Local JsonObject &JsonObjMETA = CreateJsonObject();

   &JsonObjMETA.AddProperty("OPRID", %OperatorId);
   &JsonObjMETA.AddProperty("CURRENT_TIME", %Datetime);
   &JsonObjMETA.AddProperty("TRANSACTION_ID", &msRequest.TransactionId);
   &JsonObjMETA.AddProperty("DBNAME", %DbName);

   &responseRootJSON.AddJsonObject("META", &JsonObjMETA);


   /* Push the generated XML to the response document */
   If &response.SetContentString(&responseRootJSON.ToString()) Then

   End-If;
   Return &response;

end-method;

With this simple example you can see:

How to get the raw unparsed JSON string from the request message
Parse a simple JSON object
Return back JSON data

This web service has no:

Error Handling
JSON detection of different data types
Any real practical use

Parsing a JSON Array with Nested Objects

A common pattern is receiving a top-level JSON array from an API search. Each element has nested objects and arrays:

[
  {
    "name": "Meowsy",
    "species": "cat",
    "foods": {
      "likes": ["tuna", "catnip"],
      "dislikes": ["ham", "zucchini"]
    }
  },
  {
    "name": "Barky",
    "species": "dog",
    "foods": {
      "likes": ["bones", "carrots"],
      "dislikes": ["tuna"]
    }
  }
]

To parse this, use GetJsonArray("") on the root object to get the top-level array, then loop through each element:

Local JsonParser &parser = CreateJsonParser();
Local string &jsonString;
/* &jsonString populated from web service or file */

Local boolean &bParseResult = &parser.Parse(&jsonString);

If &bParseResult = True Then
   Local JsonObject &jObj = &parser.GetRootObject();
   Local JsonArray &rootArray = &jObj.GetJsonArray("");

   Local integer &i, &j;
   Local JsonObject &rootObject, &foodObject;
   Local JsonArray &jsonArrayFavoriteFoods;
   Local string &AnimalName, &favoriteFoods;

   For &i = 1 To &rootArray.Length()
      &rootObject = &rootArray.GetJsonObject(&i);
      &AnimalName = &rootObject.GetAsString("name");

      /* Get nested object */
      &foodObject = &rootObject.GetJsonObject("foods");

      /* Get nested array */
      &jsonArrayFavoriteFoods = &foodObject.GetJsonArray("likes");

      If All(&jsonArrayFavoriteFoods) Then
         &favoriteFoods = "";
         For &j = 1 To &jsonArrayFavoriteFoods.Length()
            If &j = 1 Then
               &favoriteFoods = &jsonArrayFavoriteFoods.GetAsString(&j);
            Else
               &favoriteFoods = &favoriteFoods | ", " | &jsonArrayFavoriteFoods.GetAsString(&j);
            End-If;
         End-For;
      End-If;

      /* &AnimalName and &favoriteFoods now contain the parsed values */
   End-For;
End-If;

Extracting Boolean Values

To extract JSON boolean values, use GetBooleanProperty:

Local boolean &bCanBark = &rootObject.GetBooleanProperty("canBark");

If &bCanBark Then
   /* This animal can bark */
End-If;

Handling Invalid JSON

The Parse method on JsonParser will throw an exception on invalid JSON, so you need a try-catch block:

Local JsonParser &parser = CreateJsonParser();
Local string &jsonString;
/* &jsonString may contain invalid JSON */

try
   If &parser.Parse(&jsonString) Then
      /* Parse Success - process the JSON */
   Else
      /* Parse returned false */
   End-If;

catch Exception &e
   /* Invalid JSON - handle the error */
   /* &e.ToString() will contain the position and expected tokens */
end-try;

An error message will look something like:

Invalid token [ 8 ] at position [ 45 ], Expected tokens are: [ , ]

Dynamic JSON Parsing

If you don’t know the structure of the JSON ahead of time, you can iterate over properties using ChildCount, GetPropertyNameAt, IsJsonArray, and IsJsonObject:

Local JsonObject &jObj = &parser.GetRootObject();
Local integer &i;
Local string &propName, &propValue;

For &i = 1 To &jObj.ChildCount
   &propName = &jObj.GetPropertyNameAt(&i);

   If &jObj.IsJsonArray(&propName) Then
      /* Handle array property */
   Else
      If &jObj.IsJsonObject(&propName) Then
         /* Handle nested object */
      Else
         /* Simple value - get as string */
         &propValue = &jObj.GetAsString(&propName);
      End-If;
   End-If;
End-For;

There is no GetPropertyType method available, so you cannot easily determine if a simple value is a string, number, or boolean. You can use IsJsonArray and IsJsonObject to detect arrays and objects, but for primitive types you currently have to use GetAsString and parse the result.

Author Info

Chris Malek

Chris Malek is a PeopleTools® Technical Consultant with over two decades of experience working on PeopleSoft enterprise software projects. He is available for consulting engagements.

Work with Chris

Contents

JSON Decoding Examples

Simple REST JSON Post - Example 1

Parsing a JSON Array with Nested Objects

Extracting Boolean Values

Handling Invalid JSON

Dynamic JSON Parsing

Chris Malek

PeopleSoft Simple Web Services (SWS)

PeopleSoft Simple Web Services (SWS)

PeopleSoft Simple Web Services (SWS)

PeopleSoft Simple Web Services (SWS)