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Discover how to effectively use ModelMapper to tackle the challenge of mapping nested lists in Java, with clear examples and step-by-step instructions.
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How to Map a Nested List Using ModelMapper in Java

In the world of Java development, mapping objects between different structures can sometimes become tricky, especially when working with nested lists. A common challenge developers face is how to utilize libraries like ModelMapper to achieve this task efficiently. If you've found yourself in a similar situation, you're not alone! In this guide, we will explore how to map a nested list using ModelMapper effectively.

The Problem

You may have a source model that looks something like this:

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

And you want to map it to a destination model that is structured differently:

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

The challenge arises when you need to transform the list of IdentitySource objects into a list of NestedIdentityDestination objects, each containing an IdentityDestination object.

The Solution

After some research and experimentation, I found that leveraging a combination of converter and type mapping with ModelMapper can solve this issue effectively. Below, I will break down the solution into easy-to-follow steps.

Step 1: Create the Converter

We need to create a custom Converter that will handle the mapping of List<IdentitySource> to List<NestedIdentityDestination>. Here’s how you can define it:

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

Step 2: Configure the Type Mapping

Once you have the converter, you will need to configure the type mapping between your source and destination models. Here’s how to do it using ModelMapper:

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

Breakdown of the Code

Converter: This piece of code is crucial as it defines how each element in your source list is transformed. The map method uses streams to iterate over the IdentitySource objects, converting each to NestedIdentityDestination with the help of ModelMapper.

Type Mapping: In this part, we define how the UserSource and UserDestination types relate to one another. We specify that the conversion will use our custom converter for the nested identities mapping.

Conclusion

By following these steps, you should now be able to efficiently map a nested list with ModelMapper in Java. This approach not only simplifies the process but also enhances your code's maintainability.

If you come across any specific scenarios or have questions while implementing this solution, feel free to share your thoughts in the comments below. Happy coding!