Understanding the JSON Response

Oct 13, 2025 by wbrum.org 143 views

Introduction

In this article, we will explore how to retrieve values from a JSON response in a list using Apex in Salesforce. We will cover the process of making a REST API call to get the global value set, deserializing the JSON result, and extracting the picklist values into a list.

Understanding the JSON Response

Before we dive into the code, let's take a closer look at the JSON response we are working with. The JSON response is as follows:

{
  "size": 1,
  "totalSize": 1,
  "done": true,
  "records": [
    {
      "attributes": {
        "type": "ValueSet",
        "url": "/services/data/v45.0/sobjects/ValueSet/01d1d000000000000000000000000000"
      },
      "developerName": "My_Picklist",
      "label": "My Picklist",
      "fullName": "My_Picklist",
      "valueSetDefinition": {
        "picklistValues": [
          {
            "label": "Value 1",
            "value": "Value1"
          },
          {
            "label": "Value 2",
            "value": "Value2"
          }
        ]
      }
    }
  ]
}

As we can see, the JSON response contains a list of records, each with a picklistValues field that contains a list of picklist values.

Making the REST API Call

To get the global value set, we need to make a REST API call to the Salesforce instance. We can use the Http class in Apex to make the call. Here is an example of how to make the call:

Http http = new Http();
HttpRequest req = new HttpRequest();
req.setEndpoint('https://your-instance.my.salesforce.com/services/data/v45.0/sobjects/ValueSet');
req.setMethod('GET');
req.setHeader('Authorization', 'Bearer ' + UserInfo.getAccessToken());
req.setHeader('Content-Type', 'application/json');
req.setHeader('Accept', 'application/json');
HttpResponse res = http.send(req);

Deserializing the JSON Response

Once we have made the REST API call, we need to deserialize the JSON response into a list of records. We can use the JSON class in Apex to deserialize the response. Here is an example of how to deserialize the response:

JSONParser parser = JSON.createParser(res.getBody());
List<ValueSet> valueSets = new List<ValueSet>();
while (parser.nextToken() != null) {
    if (parser.getCurrentToken() == JSONToken.START_OBJECT) {
        ValueSet valueSet = new ValueSet();
        while (parser.nextToken() != null) {
            if (parser.getCurrentToken() == JSONToken.FIELD_NAME) {
                String fieldName = parser.getText();
                if (fieldName == 'picklistValues') {
                    parser.nextToken();
                    List<PicklistValue> picklistValues = new List<PicklistValue>();
                    while (parser.nextToken() != null) {
                        if (parser.getCurrentToken() == JSONToken.START_OBJECT) {
                            PicklistValue picklistValue = new PicklistValue();
                            while (parser.nextToken() != null) {
                                if (parser.getCurrentToken() == JSONToken.FIELD_NAME) {
                                    String fieldName2 = parser.getText();
                                    if (fieldName2 == 'label') {
                                        parser.nextToken();
                                        picklistValue.label = parser.getText();
                                    } else if (fieldName2 == 'value') {
                                        parser.nextToken();
                                        picklistValue.value = parser.getText();
                                    }
                                }
                            }
                            picklistValues.add(picklistValue);
                        }
                    }
                    valueSet.picklistValues = picklistValues;
                }
            }
        }
        valueSets.add(valueSet);
    }
}

Extracting the Picklist Values

Once we have deserialized the JSON response, we can extract the picklist values into a list. We can use a loop to iterate over the list of records and extract the picklist values. Here is an example of how to extract the picklist values:

List<String> picklistValues = new List<String>();
for (ValueSet valueSet : valueSets) {
    for (PicklistValue picklistValue : valueSet.picklistValues) {
        picklistValues.add(picklistValue.value);
    }
}

Conclusion

In this article, we have explored how to retrieve values from a JSON response in a list using Apex in Salesforce. We have covered the process of making a REST API call to get the global value set, deserializing the JSON response, and extracting the picklist values into a list. By following the steps outlined in this article, you should be able to retrieve the picklist values from a JSON response in a list.

Example Use Case

Here is an example use case for the code outlined in this article:

public class GetValueSet {
    public static void main(String[] args) {
        Http http = new Http();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://your-instance.my.salesforce.com/services/data/v45.0/sobjects/ValueSet');
        req.setMethod('GET');
        req.setHeader('Authorization', 'Bearer ' + UserInfo.getAccessToken());
        req.setHeader('Content-Type', 'application/json');
        req.setHeader('Accept', 'application/json');
    HttpResponse res = http.send(req);
    JSONParser parser = JSON.createParser(res.getBody());
    List&lt;ValueSet&gt; valueSets = new List&lt;ValueSet&gt;();
    while (parser.nextToken() != null) {
        // ...
    }
    List&lt;String&gt; picklistValues = new List&lt;String&gt;();
    for (ValueSet valueSet : valueSets) {
        for (PicklistValue picklistValue : valueSet.picklistValues) {
            picklistValues.add(picklistValue.value);
        }
    }
    System.debug(picklistValues);
}

}

This code will retrieve the picklist values from the JSON response and print them to the debug log.

Best Practices

Here are some best practices to keep in mind when working with JSON and Apex:

Use the JSON class to deserialize the JSON response.
Use a loop to iterate over the list of records and extract the picklist values.
Use a List to store the picklist values.
Use the System.debug method to print the picklist values to the debug log.

Q: What is the best way to deserialize a JSON response in Apex?

A: The best way to deserialize a JSON response in Apex is to use the JSON class. The JSON class provides a simple and efficient way to parse JSON data and convert it into a format that can be used in Apex.

Q: How do I handle nested JSON objects in Apex?

A: To handle nested JSON objects in Apex, you can use a recursive approach. You can use a loop to iterate over the JSON object and extract the values. If the value is another JSON object, you can recursively call the same function to extract the values from the nested object.

Q: What is the difference between `JSONParser` and `JSON.createParser()`?

A: JSONParser is a class that provides a way to parse JSON data. JSON.createParser() is a method that creates a new instance of the JSONParser class. You can use either JSONParser or JSON.createParser() to parse JSON data, but JSON.createParser() is a more concise and efficient way to do so.

Q: How do I handle JSON arrays in Apex?

A: To handle JSON arrays in Apex, you can use a loop to iterate over the array and extract the values. You can use the JSONParser class to parse the JSON array and extract the values.

Q: What is the best way to store the deserialized JSON data in Apex?

A: The best way to store the deserialized JSON data in Apex is to use a List or a Map. A List is a collection of values, and a Map is a collection of key-value pairs. You can use a List to store the deserialized JSON data if you need to access the values by index, and you can use a Map to store the deserialized JSON data if you need to access the values by key.

Q: How do I handle JSON null values in Apex?

A: To handle JSON null values in Apex, you can use the JSONParser class to parse the JSON data and check for null values. If a value is null, you can set it to a default value or handle it in a way that makes sense for your application.

Q: What is the best way to debug JSON data in Apex?

A: The best way to debug JSON data in Apex is to use the System.debug() method to print the JSON data to the debug log. You can also use a JSON viewer or a JSON editor to visualize the JSON data and make it easier to debug.

Q: How do I handle JSON data that contains special characters?

A: To handle JSON data that contains special characters, you can use the JSONParser class to parse the JSON data and handle the special characters. You can also use a JSON library that supports special characters, such as the JSON class in Apex.

Q: What is the best way to optimize JSON data in Apex?

A: The best way to optimize JSON data in Apex is to use a JSON library that supports optimization, such as the JSON class in Apex. You can also use techniques such as caching and lazy loading to optimize the JSON data.

Q: How do I handle JSON data that contains large amounts of data?

A: To handle JSON data that contains large amounts of data, you can use a JSON library that supports large data sets, such as the JSON class in Apex. You can also use techniques such as pagination and chunking to handle large data sets.

Q: What is the best way to secure JSON data in Apex?

A: The best way to secure JSON data in Apex is to use a JSON library that supports security features, such as encryption and authentication. You can also use techniques such as tokenization and masking to secure the JSON data.

Q: How do I handle JSON data that contains sensitive information?

A: To handle JSON data that contains sensitive information, you can use a JSON library that supports security features, such as encryption and authentication. You can also use techniques such as tokenization and masking to secure the sensitive information.

Q: What is the best way to validate JSON data in Apex?

A: The best way to validate JSON data in Apex is to use a JSON library that supports validation, such as the JSON class in Apex. You can also use techniques such as schema validation and data validation to validate the JSON data.

Q: How do I handle JSON data that contains invalid data?

A: To handle JSON data that contains invalid data, you can use a JSON library that supports error handling, such as the JSON class in Apex. You can also use techniques such as error handling and exception handling to handle invalid data.