Write if condition for stringfields in JSON Generator

Question

There are group of fields I am querying and putting them in JSON. Some of these fields may be blank which is making previous test classes fail throwing a nul pointer exception.

**Present Code ** There are many other fields. I am just putting a sample

        gen.writeStringField('DayPhone', c.contact.OtherPhone);
        gen.writeStringField('EveningPhone', c.contact.HomePhone);
        gen.writeStringField('WorkPhone', c.contact.phone), c.account.Billing_Account_Number__c);

Currently, I have to write if condition like this for it to work:

    if(c.contact.HomePhone != null){gen.writeStringField('EveningPhone', c.contact.HomePhone);}
    if(c.contact.phone != null){gen.writeStringField('WorkPhone', c.contact.phone);}
    if(c.contact.MobilePhone != null){gen.writeStringField('Mobile', c.contact.MobilePhone);}

Since I am adding if on every line, I wanted to know if any check can be done all at once or any other option.

**Update ** I found that using JSON serialize can avoid this exception. So I am planning to change my code from JSON Generator to serialize instead of writing if condition on all fields. But is there a way to add if condition while serializing.

Ex: When I use JSONGenerator I can add if condition like this:

if(c.accountId != null){ gen.writestringfield(c.accountId); }

which adds this value to json only if accountid is not null. But in case of serialize, it is

public class caseVars {
           public string caseId;
        public string accountId;
}

public static void postCases (list<case> c1) {
   for(case c: c1){
            caseVars caseVar = new caseVars();
            caseVar.caseId = IdSplit(c.Id); 
     if(c.accountId != null){ caseVar.accountId = c.accountId; }
}

I believe in the second method, evenif accountId is null, there is a label named accountId with null value in the Jsonstring. Is there a way to control that ? ( Is there a way not to show accountId field at all in JSON string if there is no accountId on case)

Thanks

Answer 1

One of the options is to have a map of the API fields on the contact record to their corresponding key values for your JSON string. Then you could put your Contact record into an sObject variable and use the .get method to dynamically retrieve a field value based on the API name:

sObject contactSObject = c.contact;

Map <String, String> fieldNames = new Map <String, String> ('HomePhone' => 'EveningPhone', 'Phone' => 'WorkPhone', 'MobilePhone' => 'Mobile');

for (String fieldName : fieldNames.keySet())
{
    if (contactSObject.get(fieldName) != null)
    {
        gen.writeStringField(fieldNames.get(fieldName), (String)contactSObject.get(fieldName));
    }
}

Be careful with the types as not all fields return String. I'll leave that to you to sort out.