Understanding Reserved Words in Apex

Oct 13, 2025 by wbrum.org 24 views

Introduction

When working with JSON data in Apex, you may encounter a situation where the property names in the JSON are reserved words in Apex. This can cause issues when trying to deserialize the JSON into an object using the JSON.deserialize method. In this article, we will explore how to deserialize JSON properties that are reserved words in Apex.

Understanding Reserved Words in Apex

Apex has a set of reserved words that cannot be used as variable names or property names. These reserved words include keywords such as class, interface, public, private, static, final, void, return, if, else, for, while, switch, case, default, break, continue, throw, try, catch, finally, new, this, super, extends, implements, instanceof, enum, goto, const, volatile, synchronized, transient, strictfp, abstract, native, strictfp, assert, boolean, byte, char, double, float, int, long, short, String, void, true, false, and null.

Deserializing JSON Properties that are Reserved Words in Apex

When deserializing JSON properties that are reserved words in Apex, you can use the JSON.deserialize method with a custom mapping to map the reserved word property names to valid Apex property names.

Using a Custom Mapping

You can create a custom mapping to map the reserved word property names to valid Apex property names. Here is an example of how you can do this:

public class CustomMapping {
    @Key('class')
    public String className;
    @Key('public')
    public String publicProperty;
    @Key('private')
    public String privateProperty;
    // Add more mappings as needed
}

Then, you can use the JSON.deserialize method with the custom mapping to deserialize the JSON:

string jsonString = '{...}';
CustomMapping customMapping = (CustomMapping)JSON.deserialize(jsonString, CustomMapping.class);

Using a Wrapper Class

Another approach is to use a wrapper class to wrap the reserved word property names. Here is an example of how you can do this:

public class ReservedWordWrapper {
    public String _class;
    public String _public;
    public String _private;
    // Add more mappings as needed
}

Then, you can use the JSON.deserialize method to deserialize the JSON into the wrapper class:

string jsonString = '{...}';
ReservedWordWrapper wrapper = (ReservedWordWrapper)JSON.deserialize(jsonString, ReservedWordWrapper.class);

Using a Custom Deserializer

You can also create a custom deserializer to handle the reserved word property names. Here is an example of how you can do this:

public class CustomDeserializer {
    public Object deserialize(JSON json) {
        // Handle the reserved word property names here
        // For example:
        if (json.containsKey('class')) {
            json.put('className', json.get('class'));
            json.remove('class');
        }
        // Add more mappings as needed
        return json;
    }
}

Then, you can use the custom deserializer with the JSON.deserialize method:

string jsonString = '{...}';
CustomDeserializer deserializer = new CustomDeserializer();
Object obj = deserializer.deserialize(JSON.deserialize(jsonString));

Conclusion

In this article, we explored how to deserialize JSON properties that are reserved words in Apex. We discussed three approaches: using a custom mapping, using a wrapper class, and using a custom deserializer. Each approach has its own advantages and disadvantages, and the choice of approach depends on the specific requirements of your project.

Additional Tips and Considerations

When using a custom mapping, make sure to update the mapping whenever the JSON schema changes.
When using a wrapper class, make sure to update the wrapper class whenever the JSON schema changes.
When using a custom deserializer, make sure to handle all the reserved word property names in the JSON.
Consider using a library or framework that provides built-in support for deserializing JSON properties that are reserved words in Apex.
Consider using a different data format, such as XML or CSV, if the JSON schema is too complex or if the reserved word property names are a problem.

Example Use Cases

Here are some example use cases for deserializing JSON properties that are reserved words in Apex:

Deserializing a JSON object that contains a property named class:

string jsonString = '{...}';
CustomMapping customMapping = (CustomMapping)JSON.deserialize(jsonString, CustomMapping.class);
System.debug(customMapping.className);

Deserializing a JSON object that contains a property named public:

string jsonString = '{...}';
CustomMapping customMapping = (CustomMapping)JSON.deserialize(jsonString, CustomMapping.class);
System.debug(customMapping.publicProperty);

Deserializing a JSON object that contains a property named private:

string jsonString = '{...}';
CustomMapping customMapping = (CustomMapping)JSON.deserialize(jsonString, CustomMapping.class);
System.debug(customMapping.privateProperty);

Note that these are just examples, and you should adjust the code to fit your specific use case.

Conclusion

In conclusion, deserializing JSON properties that are reserved words in Apex can be a challenge, but there are several approaches you can take to solve the problem. By using a custom mapping, a wrapper class, or a custom deserializer, you can deserialize JSON properties that are reserved words in Apex and work with the data in your Apex code.

Introduction

In our previous article, we explored how to deserialize JSON properties that are reserved words in Apex. We discussed three approaches: using a custom mapping, using a wrapper class, and using a custom deserializer. In this article, we will answer some frequently asked questions (FAQs) about deserializing JSON properties that are reserved words in Apex.

Q: What are reserved words in Apex?

A: Reserved words in Apex are keywords that cannot be used as variable names or property names. These keywords include class, interface, public, private, static, final, void, return, if, else, for, while, switch, case, default, break, continue, throw, try, catch, finally, new, this, super, extends, implements, instanceof, enum, goto, const, volatile, synchronized, transient, strictfp, abstract, native, strictfp, assert, boolean, byte, char, double, float, int, long, short, String, void, true, false, and null.

Q: Why can't I use reserved words as property names in Apex?

A: Reserved words in Apex are used by the compiler to identify the structure of the code. If you use a reserved word as a property name, it can cause confusion and errors in the code.

Q: How do I deserialize JSON properties that are reserved words in Apex?

A: There are several approaches you can take to deserialize JSON properties that are reserved words in Apex. You can use a custom mapping, a wrapper class, or a custom deserializer.

Q: What is a custom mapping?

A: A custom mapping is a way to map the reserved word property names in the JSON to valid Apex property names. You can create a custom mapping class that contains the reserved word property names and their corresponding valid Apex property names.

Q: What is a wrapper class?

A: A wrapper class is a class that wraps the reserved word property names in the JSON. You can create a wrapper class that contains the reserved word property names and their corresponding valid Apex property names.

Q: What is a custom deserializer?

A: A custom deserializer is a class that handles the deserialization of the JSON properties that are reserved words in Apex. You can create a custom deserializer class that handles the deserialization of the JSON properties.

Q: How do I use a custom mapping?

A: To use a custom mapping, you need to create a custom mapping class that contains the reserved word property names and their corresponding valid Apex property names. Then, you can use the custom mapping class with the JSON.deserialize method to deserialize the JSON properties.

Q: How do I use a wrapper class?

A: To use a wrapper class, you need to create a wrapper class that contains the reserved word property names and their corresponding valid Apex property names. Then, you can use the wrapper class with the JSON.deserialize method to deserialize the JSON properties.

Q: How do I use a custom deserializer?

A: To use a custom deserializer, you need to create a custom deserializer class that handles the deserialization of the JSON properties that are reserved words in Apex. Then, you can use the custom deserializer class with the JSON.deserialize method to deserialize the JSON properties.

Q: What are some best practices for deserializing JSON properties that are reserved words in Apex?

A: Some best practices for deserializing JSON properties that are reserved words in Apex include:

Using a custom mapping or a wrapper class to map the reserved word property names to valid Apex property names.
Using a custom deserializer to handle the deserialization of the JSON properties.
Avoiding the use of reserved words as property names in the JSON.
Using a different data format, such as XML or CSV, if the JSON schema is too complex or if the reserved word property names are a problem.

Q: What are some common pitfalls to avoid when deserializing JSON properties that are reserved words in Apex?

A: Some common pitfalls to avoid when deserializing JSON properties that are reserved words in Apex include:

Not using a custom mapping or a wrapper class to map the reserved word property names to valid Apex property names.
Not using a custom deserializer to handle the deserialization of the JSON properties.
Using reserved words as property names in the JSON.
Not handling the deserialization of the JSON properties correctly.

Q: How do I troubleshoot issues with deserializing JSON properties that are reserved words in Apex?

A: To troubleshoot issues with deserializing JSON properties that are reserved words in Apex, you can:

Check the JSON schema to ensure that it is correct and that the reserved word property names are not being used.
Check the custom mapping or wrapper class to ensure that it is correct and that the reserved word property names are being mapped correctly.
Check the custom deserializer to ensure that it is correct and that it is handling the deserialization of the JSON properties correctly.
Use the System.debug statement to debug the code and identify any issues.

Conclusion

In this article, we answered some frequently asked questions about deserializing JSON properties that are reserved words in Apex. We discussed the different approaches you can take to deserialize JSON properties that are reserved words in Apex, including using a custom mapping, a wrapper class, or a custom deserializer. We also discussed some best practices and common pitfalls to avoid when deserializing JSON properties that are reserved words in Apex.