[SalesForce] How tognore Unknown Json Properties in Apex

I'm doing a web service call, and parsing the json response into a wrapper object for display on a Visualforce page.

My wrapper object looks like:

public class CustomerAddresses {
    public String line1 {get; set;}
    public String line2 {get; set;}
    public String city {get; set;}
    public String state {get; set;}
}

My json parser looks like:

String fieldName = parser.getCurrentName();                
            if(fieldName == 'addr' && parser.getCurrentToken() == JsonToken.START_ARRAY){
                while(parser.nextToken()!= JsonToken.END_ARRAY){
                    if(parser.getCurrentToken()==JSONToken.START_OBJECT){
                        CustomerAddresses s = (CustomerAddresses)parser.readValueAs(CustomerAddresses.class);
                        customerAddressList.add(s);
                    }
                }
            }

and the json file looks something like:

    {
   "theresponse":{
      "addrs":{
         "addr":[
            {
               "line1":"11562 TEST DR",
               "line2":"ORANGEVILLE",
               "city":"GARDEN GROVE",
               "state":"AZ"
            },
            {
               "line1":"123 TEST BLVD",
               "line2":"TREE HARBOR",
               "city":"FAIRMONT",
               "state":"CA"
            }
         ]
      },

Here's my problem, if (in the future) someone adds another attribute to the json file, such as "zip" (see example below), then my class breaks because I can't create an object without the attribute being declared in the CustomerAddresses class. How can I ignore json attributes that aren't in my class CustomerAddresses?
Thank you in advance for any help with this!!

Ex: bad json file:

        {
   "theresponse":{
      "addrs":{
         "addr":[
            {
               "line1":"11562 TEST DR",
               "line2":"ORANGEVILLE",
               "city":"GARDEN GROVE",
               "state":"AZ",
               "zip":"80001"
        },

Best Answer

The documentation for readValueAs says (emphasis mine):

When deserializing JSON content into an Apex class in any API version, or into an object in API version 35.0 or later, no exception is thrown. When no exception is thrown, this method ignores extraneous attributes and parses the rest of the JSON content.

My reading of this is that your code should continue to work when extra JSON attributes are added. But I suggest you create a test case to ensure that the code does what the documentation says.

Related Solutions

[SalesForce] How to Deserialze JSON Object and save them to salesforce

I prefer using the JSON.deserializeUntyped() to get specific values.

//use the Map<String,Object> to get the values of the JSON
String jsonString = 'YOUR JSON BODY';
Map<String,Object> rawObj = (Map<String,Object>) JSON.deserializeUntyped(jsonString);
//the response fields are stored as an object in the "response": field. So you have to get that field before getting it's child fields.
Map<String,Object> responseObj = (Map<String,Object>)rawObj.get('response');
//this will get child objects
Map<String,Object> userDetails = (Map<String,Object>) responseObj.get('user_detail');
//loop through details
for (String field : userDetails.keySet()){
    system.debug('The field: ' + field);
    Object o = userDetails.get(ks);
    system.debug('The value: ' + o);
    //if you want to reference an sObject field you could do
    MySObjectRec.put(ks,o);
}
//select a specific value
String requestStatus = (String) responseObj.get('request_status');
String firstName = (String) userDetails.get('firstname');

You could also use a List<Object> listObj = responseObj.get('arrayVar'); if the value is an array and then loop through that.

Apex JSON – What is the Correct JSON/Apex Strategy?

If you know the structure of the JSON before you get it then the easiest way is to create a class to define the Object.

For Example, given the following JSON String

{
    "id" : "someID",
    "street" : "someStreet",
    "listOfClass" : [
              {
                 "myVar" : "test"
              }
            ]
    "myArray" : ["1","2","3"]
}

Define the object as such:

public class myJSONClass{

    public string id;
    public string street;
    public listOfClass[] listOfClass;
    public String[] myArray;

    public class listOfClasses{
       public String myVar;
    }

}

Do not think of it as a class to clutter your other classes, think of it as an object definition (what it is)

Then simply deserialize as follows:

myJSONClass obj = (myJSONClass)JSON.deserialize(JSONSTRING,myJSONClass.class);

Where it becomes tricky is when you are using reserved names or an unknown structure.

In most of those cases you need to use the JSON Parser methods to parse the string.The exception is if you only have a FEW reserved names you can replace them as such

JSONString = JSONString.replace('name','name_Z');

then define the property in the class as name_Z. It will save a lot of work.

Back to your original point, if you have no class you can deserialize as such:

Map<String,Object> obj = JSON.deserializeUntyped(JSONString);

Then you can just cast everything to strings:

Map<String,String> results = New Map<String,String>();
for(String key : obj.keySet()){
   results.put(key,string.valueOf(obj.get(key));
}

However in this case you lose the structure. For example, in your string if you have lists, arrays, etc, you get the string representation of the values and not the actual structure. More useful to define a class and work with it.

Note You do not have to have everything defined in the class to deserialize unless you use deserializeStrict. So if in my first example you removed public String id it would still deserialize

In all the above examples, make sure to check for nulls and errors

Best Answer

Related Solutions

[SalesForce] How to Deserialze JSON Object and save them to salesforce

Apex JSON – What is the Correct JSON/Apex Strategy?

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