How can I serialize an object to JSON without properties that are null?

Question

To communicate with a REST interface on a private system, I need to send a JSON message from a trigger. I have a message object that has some fields, lists and a child object:

public class MerchantConfig {

public class MIDConfig {
    public String mid;
    public String currencyCode;
    public String cardTemplateName;
    public String paymentPanelRestriction;
    public List<String> restrictedCountries; 
    public String paymentPanelRestrictionForCountries;
}

public String merchantName;
public String sopgTemplateName;
public Integer dispositionTimeWindowInMinutes;
public List<String> features;
public Boolean activateImmediately;
public List<MIDConfig> midConfiguration;
}

I can serialize it to JSON using the built-in serializer:

String body = JSON.serializePretty([MerchantConfig instance]);

The result:

{
  "sopgTemplateName" : null,
  "midConfiguration" : [ {
    "restrictionCountries" : [ "DE", "AT" ],
    "paymentPanelRestrictionForCountries" : "MANDATORY",
    "paymentPanelRestriction" : "OPTIONAL",
    "mid" : "1000000001",
    "currencyCode" : "EUR",
    "cardTemplateName" : null
  }, {
    "restrictionCountries" : [ ],
    "paymentPanelRestrictionForCountries" : "",
    "paymentPanelRestriction" : "OPTIONAL",
    "mid" : "1000000002",
    "currencyCode" : "USD",
    "cardTemplateName" : null
  }, {
    "restrictionCountries" : [ ],
    "paymentPanelRestrictionForCountries" : "",
    "paymentPanelRestriction" : "PROHIBITED",
    "mid" : "1000000003",
    "currencyCode" : "AUD",
    "cardTemplateName" : null
  } ],
  "merchantName" : "Test Merchant",
  "features" : [ XYZ ],
  "dispositionTimeWindowInMinutes" : 10,
  "activateImmediately" : true
}

How can I serialize this object so that all properties that are null don't show up in the JSON string?

In this example, "sopgTemplateName" and all "cardTemplateName" properties are null and should not appear in the JSON string. The empty list "restrictionCountries" should still appear as an empty list, though.

Answer 1

Depending on your use case, you might consider holding your state in a generic Map<String,Object> rather than in specific fields in an Apex class.

You can then use JSON.serialize(Map) which will simply omit the pseudo-fields that have not been added to the Map. Each Object in the Map could be a list or another map or a simple type.

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foobarforce.com/.../apex-method-of-the-day-json-serialize-object/

Answer 2

This is old thread but it may help someone looking for out-of-box solution. Seems like Salesforce recently updated its API. Please try

String body = JSON.serializePretty([MerchantConfig instance], true);

I have tested it and it works.

serializePretty(objectToSerialize, suppressApexObjectNulls)

Suppresses null values when serializing Apex objects into JSON content and generates indented content using the pretty-print format.

Answer 3

Based on this JSON.Serialize method not returning null fields it looks like the behaviour is version dependent and that API version 25 (probably) strips out the nulls. I suggest you test with API versions from say 24 upwards and see what behaviour you get.

If you do find a version that strips out the nulls, set the class to that API version and add a large comment in your code that the API version is critical and why.

PS See georg w's comment - there is no version as far back as 25 that strips the nulls.

PPS If this is a one-off, then you can write your own serializer for this specific object using the JSONGenerator that includes the null checks.