[SalesForce] Extra Backslash in Json String when exposing webservice

I am creating a middle ware in Salesforce. The external System1 calls my SFDC org and I call external system2 from SFDC in turn. The external system2 gives me Json string like {"Car":"Fiat","Model":"2009"}.
I use the following code to return back the json to the calling external system1

//Call external system2 and get response. No DML in between Only Callouts
RestContext.response.addHeader('Content-Type', 'application/json');
return '{"Car":"Fiat","Model":"2009"}';

But i get extra backslash like this in response from SFDC org

"{\"Car\":\"Fiat\",\"Model\":\"2009\"}"

Any solution for this ?

Best Answer

It looks like you are returning a String from your REST endpoint which is then being sanitised by Salesforce JSON serializer.

Any object returned from a method in an @RestResource annotated class is automatically serialized into JSON/XML for you, you don't need to do it yourself.

If you want to return a JSON object from an @RestResource class you have two choices.

Create the object as a class and return an instance of it

global class MyRestObject {
    global String Car;
    global String Model;
}

// Then in your RestResource method
RestContext.response.addHeader('Content-Type', 'application/json');
MyRestObject obj = new MyRestObject();
obj.Car = 'Fiat';
obj.Model = '2009';
return obj;

You will also have the change the return type of you method from String to MyRestObject for this to work. The Salesforce JSON serializer will turn it into JSON for you before it returns it to callers of your REST endpoint.

Set the body directly

RestContext.response.addHeader('Content-Type', 'application/json');
RestContext.response.responseBody = Blob.valueOf('{"Car":"Fiat","Model":"2009"}');

In this case you do have to do the conversion to JSON yourself (or you could use the object from the first example above with JSON.serialize()).

You will also have the change the return type of your method from String to void for this to work. Only return values are run through the Salesforce serializer, so by returning nothing you are telling Salesforce to leave the body of your response alone.

Related Solutions

[SalesForce] How to update an Account field value from an External Service after a future call

To answer your question, you'll have to make a static class / variable that will prevent you from running your async process(es) multiple times since you'll get stuck in an infinite loop otherwise. Something like this will accomplish what you are asking for.

Class:

SF2NSPassJsonData{
    private static Boolean isAtFutureInUse;
}

Trigger:

trigger trgSF2NSAccount on Account (after update) {
    // if no at future process has been fired off, do process
    if(null == SF2NSHandleAccount.isAtFutureInUse || !SF2NSHandleAccount.isAtFutureInUse){
        // generate JSON String
        ....
        // queue up for webservice call
        SF2NSHandleAccount.isAtFutureInUse = true;
        SF2NSHandleAccount.handleAccount(idlist, jsonData);
    }
}

Your system should in my opinion return to you the Salesforce id if you provide it. However if you cannot get this information back, Salesforce allows you to use a DML statement called Upsert

upsert record externalSystemId__c;

Truthfully, I would use the streaming API if possible. (even if it's a middle man integration)

For one, currently, you'll be delaying all updates and they'll have to wait on your response in order for you to process your records in a timely manner. This will delay bulk updates to your system.
Secondly, your data will be more real time as you won't have to wait on your async process to get queued up and processed.
Lastly, there is a governor limit on how many @futres you are allowed to run per rolling 24 hours.

[SalesForce] Unexpected character (‘}’ during JSON desearilization

Once you add the curly brackets, your JSON looks like this

{
  [
    {
     \"sampleNumber\":\"WO-02609\",
     \"SampleID\":\"a3F5C000000CHATTAM\",
     \"state\":\"Open\"
   }
 ]
}

Which is invalid JSON because you have an list inside of an object without a property name. Instead of adding the curly brackets, change your code to deserialize the JSON differently:

List<ResponseJSON> respJson =(List<ResponseJSON>)JSON.deserialize(response.getBody(), List<ResponseJSON>.class);

Since your JSON starts with square brackets, it's read as a list. Ergo, you should deserialize it as one.

Update

Since you mention in the comments that the external system is adding quotes to your code, I suspect you can do this to make the string JSON-friendly before deserializing

String jsonString = (String)JSON.deserialize(response.getBody(), String.class); 

List<ResponseJSON> respJson =(List<ResponseJSON>)JSON.deserialize(jsonString, List<ResponseJSON>.class);