Using cWebHttpHandler with JSON instead of tWebValueTree

From this forum post: https://support.dataaccess.com/Forums/showthread.php?68231-ToDo-Describe-call-mode-and-a-few-more-questions&p=371095#post371095

Reposting it here so I can quickly find it next time I need it (sorry, not sorry)

It is indeed true that for most situations the tWebValueTree is not needed any more. ClientActions and ServerActions can now use JSON Handles or structs & arrays that are directly serialized. So when calling a server action you can now do the following: Code:

// Create data objects var oData = {

   labels : ["January","February","March","April","May","June","July"],
   datasets : [{
       strokeColor : "rgba(220,220,220,1)",
       data : [65,59,90,81,56,55,40]
   },{
       strokeColor : "rgba(151,187,205,1)",
       data : [28,48,40,19,96,27,100]
   }]

};

// Send call to the server this.serverAction("ProcessData2", [ 2, 1 ], oData, function(oEvent){

   alert(oEvent.sReturnValue);

});

Code:

// Function called as server action Function ProcessData2 Integer iParam1 Integer iParam2 Returns String

   tActionData tData
   Handle hoJson
   
   //  Retrieve and deserialize data
   Get phoActionJsonData to hoJson
   Get JsonToDataType of hoJson to tData
   
   Function_Return tData.labels[3]

End_Function

So instead of ptActionData you use phoActionJsonData which gives a cJsonObject representing the data. Note that you do not have to cleanup this JSON Handle.

For client actions you can do the following: Code:

Procedure ProcessDataOnClient2

   //  Send the client action
   String[] aParams
   tActionData tData
    
   //  Generate some data
   Move "Januari"      to tData.labels[0]
   Move "Februari"     to tData.labels[1]
   Move "#FF0000"      to tData.datasets[0].strokeColor
   Move 55             to tData.datasets[0].data[0]
   Move 88             to tData.datasets[0].data[0]
    
   //  Call the client action
   Send ClientAction "processData2" aParams tData

End_Procedure

Code:

// Client action called with action data processData2 : function(){

   var tData;
   
   // Retrieve value tree and deserialize
   tData = this._tActionData;
   
   // Do something with the data
   alert(tData.datasets[0].strokeColor);

}

Note that ClientAction takes a variant parameter that it serializes to JSON. Both API's are backwards compatible so working with tWebValueTree still works. The value tree's are also still used for client web properties.