How to Successfully Serialize a JSON Object Deserialized with OpenJson() in SQL Server

Learn how to convert a JSON object deserialized using OpenJson() back into a string format in SQL Server, using effective methods and examples.
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Understanding JSON Serialization and Deserialization in SQL Server

When working with JSON data in SQL Server, you may often face the challenge of modifying or updating specific values within a JSON object. In this guide, we will address a common issue faced when trying to serialize an object that has been previously deserialized using OPENJSON().

The Problem: Serialization After Deserialization

You may have a JSON object stored as an NVARCHAR in SQL Server, as illustrated below:

[[See Video to Reveal this Text or Code Snippet]]

When you use OPENJSON() to deserialize this object, you can easily store it into a table, modify certain values, and then aim to serialize it back to its original format. However, an attempt to do so using FOR JSON AUTO might not yield the expected results and can look something like this:

[[See Video to Reveal this Text or Code Snippet]]

The output is far from your original JSON string, which presents a clear challenge.

The Solution: Methods to Serialize Back to JSON

Method 1: Using JSON_MODIFY()

If your goal is to change a specific key in your JSON object directly, JSON_MODIFY() is the ideal function to use. Here’s how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Method 2: Using OPENJSON with Explicit Schema

If you prefer to follow your original method of using OPENJSON(), make sure to use it with an explicit schema. Below is the breakdown of steps:

Prepare your JSON data.

Deserialize it with OPENJSON() and define the schema.

Perform the update.

Serialize it back using FOR JSON with a corrected wrapper.

Here's an example:

[[See Video to Reveal this Text or Code Snippet]]

Method 3: Simplifying with FOR JSON PATH

As an added simplification, you might consider using FOR JSON PATH. Here’s how you can achieve it:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Handling JSON in SQL Server can indeed be complex, especially when you need to modify and serialize data. By using the right approach—whether it’s JSON_MODIFY() for direct changes, OPENJSON() for detailed manipulation, or FOR JSON PATH for simplicity—you can effectively manage your JSON objects.

Feel free to experiment with these methods and choose the one that aligns best with your specific use case. Happy coding!