[SalesForce] How to convert list data into json in APEX

EDIT:

I have tried something like this and I get no errors but does not display anything in the system.debug.

    String JSONString = JSON.serialize(mapWrapper);
    system.debug('JSONString : ' + JSONString );

END

Is there way to convert object list into json output?

Defined map as following:

Map<string, List<WrapperDay>>  mapWrapper = new Map<string, List<WrapperDay>>();

Output:

mapWrapper: {Monday=(WrapperDay:[index=0, record=employee:[isAllDay=false, selectedDay=Monday, selectedSection=1, selectedTo=3]]), Tuesday=(WrapperDay:[index=0, record=employee:[isAllDay=false, selectedDay=Tuesday, selectedSection=3, selectedTo=3]], WrapperDay:[index=1, record=bannerAdTimeClass:[isAllDay=false, selectedDay=Tuesday, selectedSection=4, selectedTo=3]])}

Best Answer

Fortunately Salesforce has a class to serialize and deserialize JSON. In this documentation you can find examples on how to serialize and deserialize. The examples work with single objects, but I believe you can get those in a loop and process multiple objects (like your list of custom type).

Edit:

You probably have something wrong in your code or in your logic. The following example works just fine for me:

public class Fruit {
    public Boolean isEdible;
}
public class Tree {
    public String fruit;
    public Integer age;
    public List<Fruit> fruits;
}

public String parse(){
    Tree t1 = new Tree();
    t1.fruit = 'Apple';
    t1.age = 5;

    Tree t2 = new Tree();
    t2.fruit = 'Orange';
    t2.age = 3;

    Fruit f1 = new Fruit();
    Fruit f2 = new Fruit();
    f1.isEdible = true;
    f2.isEdible = false;

    t1.fruits = new List<Fruit>{f1, f2};
    t2.fruits = new List<Fruit>{f2, f2};
    return JSON.serialize(new List<Object>{t1, t2});
}

System.debug(parse());

and it gives me:

[{"fruits":[{"isEdible":true},{"isEdible":false}],"fruit":"Apple","age":5},{"fruits":[{"isEdible":false},{"isEdible":false}],"fruit":"Orange","age":3}]

Maybe you should try to serialize a list instead of a Map object? I don't know if this can be the issue in your case.

Related Solutions

[SalesForce] Storing json as a String field is giving wrong value

The reason I asked to see all of the code is because sometimes when working with large sets of code, passing variables in and out of methods can have unexpected side effects. Is it possible you are having an issue with passing variables into and back out of methods? Apex uses pass by value for primitive data types (such as a Map or String). If at any point you set jsonAsMap = <something> you could be running into this issue. Here is a perfect example from the reference:

We’ll illustrate this with some code samples. But first, let’s step back and define these terms.

“Pass by value” means when a method is called, a second copy of the parameter variable is made in memory, and this copy is passed to the method as a parameter. This copy can be modified in the method, but the original variable in the caller is unchanged, and the changes to the copy are lost upon return.

“Pass by reference” means when a method is called, that actual variable is passed to the method.

As described in the new developer’s guide text, Apex is not passing anything by reference. It is passing the reference (i.e., the memory address) by value, which allows the developer to change fields on the object and call methods (like list.add()) on the object.

Let’s illustrate with some code. First, an example where we get apparent pass-by-reference behavior:
List fillMe = new List();
PassByWhatNow.reference(fillMe);
System.assertEquals(fillMe.size(),5);   //five items, as expected

/*  calls this method
public static void reference(List m) {
    List la = [select id, name from Account limit 5];
    for (Account a : la) m.add(a);
}
*/
In this example, the parameter passed to the function, behind the scenes, is a pointer to the fillMe collection, passed by value. That is to say, we took the memory address and copied it – but it is the same memory address number in both places. When the add() function is called on the copy, that same memory location is modified by adding the specified items to the list. So when we return to the calling program, the modifications made in the static function are visible. So far, so good.

Now let’s look at an example where things break down.
List createMe = new List();
PassByWhatNow.referenceNew(createMe);
System.assertEquals(createMe.size(),0);   //nothing in the list

/* calls this method
public static void referenceNew(List m) {
    m = new List([select id, name from Account limit 5]);
}
*/
Again, we pass a copy of the list’s memory address to the function. However, this time, the function is initializing the variable anew. When the “new” function is called, new memory is allocated. This is the big difference.

The copy of the memory address passed as a parameter is overwritten with the address of the newly allocated memory. The original, however, is not overwritten. That change in address is not known to the caller!

Any subsequent actions done in the method are on that new memory address rather than the original object address. These changes, including the addition of the Accounts to the list, can not be available to the caller, since it only knows of the original address. No actions were done on this address; the list on the caller is therefore unchanged, still empty as it was when the call was made.

While Apex usually does behave as if we’re passing variables by reference, we’re not truly passing by reference. There are a few situations where the distinction is important, as detailed here. Now you know more, and you are a stronger developer.

[SalesForce] Apex JSON.serialize() with null values (RELOADED)

Nulls are being rendered in the latest JSON (32.0/33.0). You must explicitly the set the value to null for it to work. Consider the following code:

Account a = new Account(Name='test',Industry=null);
System.debug(LoggingLevel.ERROR, JSON.serialize(a));

Output:

{"attributes":{"type":"Account"},"Name":"test","Industry":null}

If you need every single field, you'll have to do something like:

Account a = new Account();
for(SObjectField f: account.sobjecttype.getdescribe().fields.getmap().values()) {
    try { a.put(f, null); } catch(exception e) { }
}

Even better, you could always just use a Map, which avoids the errors of field editability:

Map<String, Object> a = new Map<String, Object>();
SObject b = [SELECT Id, Name FROM Account LIMIT 1];
for(SObjectField f: account.sobjecttype.getdescribe().fields.getmap().values()) {
    try { a.put(String.valueOf(f), b.get(f)); } 
    catch(Exception e) { a.put(String.valueOf(f), null); }
}
System.debug(logginglevel.error, json.serialize(a));

I've just tried this code in executeAnonymous and came up with fully realized JSON. Note that I use a try-catch here because queried SObjects generate errors for missing fields. If you're using a manually constructed SObject, you'll not have to worry about catching errors.

Finally, note that executeAnonymous tends to always run in the latest version. You won't normally see differences in execution contexts because the entire transaction is set to version 32.0 mode when running executeAnonymous. To emulate a lower version, you'd have to write a Visualforce page and set the version of the page to a lower value, and then also set the controller's version to that lower value, etc...

Alternatively, you could write a REST class, and call that REST function. That should also set the version correctly. Since executeAnonymouse is basically an eval(), it tends to behave in the latest version, because it has to be compiled on demand.

Best Answer

Related Solutions

[SalesForce] Storing json as a String field is giving wrong value

[SalesForce] Apex JSON.serialize() with null values (RELOADED)

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