How to jenerate JSON format using wrapper class?

Question

Please see the below code I have done some modification,

@RestResource(urlMapping='/instructionsRestCall/*') global with sharing class InstructionsRestService { @HttpGet global static List getInstructions(){

    RestRequest request = RestContext.request;
    RestResponse response = RestContext.response;

    String instId = request.requestURI.subString(request.requestURI.lastIndexOf('/'));
    //Send list of Instruction details as per the provided JSON format for Instruction records where Category Type Code (catTypeCd__c) is not null
    List<Instructions__c> instList = [select Country__c,Category__c,SubCategory__c,Requirements__c,catTypeCd__c from Instructions__c];
    system.debug('Instructions List->>>>'+instList);      

    List<requestTypes> catWrapList = new List<requestTypes>();

    List<countryWrapper> counWrapList = new List<countryWrapper>();
    for(Instructions__c ins : instList){
        if(ins.catTypeCd__c != null){

            countryWrapper countWrap = new countryWrapper();
            requestTypes catWrap = new requestTypes();
            caseTypes innWrap = new caseTypes();

            countWrap.corpCode = ins.Country__c;
            catWrap.name = ins.Category__c;
            innWrap.name = ins.SubCategory__c;
            innWrap.value = ins.Requirements__c;
            innWrap.categoryTypeCode = ins.catTypeCd__c;
            countWrap.requestTypes = catWrap;
           // countWrap.innerWrapper = innWrap;
            countWrap.requestTypes.caseTypes = innWrap;
            counWrapList.add(countWrap);
        }    
    }
    system.debug('Result from WrapperList->>>>'+counWrapList);
    return counWrapList;
    //return JSON.serialize(counWrapList);
}        

global class countryWrapper{
    public String corpCode{get;set;}
    public requestTypes requestTypes{get;set;}
    //public innerWrapper innerWrapper{get;set;}
}
global class requestTypes{
    public String name{get;set;}
    public caseTypes caseTypes{get;set;}
}
global class caseTypes{
    public String name{get;set;}
    public String value{get;set;}
    public Double categoryTypeCode{get;set;}
}

}

I want this this corpCode will be in first position and after that requestType. What is wrong with my wrapper. Thanks in advance,

Answer 1

You cannot generate the format specified because it is not valid JSON.

A map always requires a key for each element, and you are missing that structure here:

        {
            "something",
             [
                {
                    Subcategory__c: "something",
                    Requirements__c: "something",
                    catTypeCd__c: "1234",
                }
            ]
        }

More generally, if you want to generate a JSON map, you need to be serializing an Apex object (where each field becomes a key, and its value the corresponding value), or an actual Apex Map instance. As you can see in your generated JSON, this structure:

global class categoryWrapper{
    public String category{get;set;}
    public innerWrapper innerWrapper{get;set;}
}

does not produce a JSON map where the key category maps to the value of innerWrapper. To get a result like that, you'd need something along the lines of

global class categoryWrapper{
    public innerWrapper category {get;set;}
}