Solving the Automapper Challenge: Mapping a List of Strings to a List of Objects

Learn how to effectively use `Automapper` to map a list of strings to a list of objects, ensuring your data is accurately transferred between classes.
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This video is based on the question https://stackoverflow.com/q/67482068/ asked by the user 'Mateusz Duda' ( https://stackoverflow.com/u/11156218/ ) and on the answer https://stackoverflow.com/a/67482415/ provided by the user 'Tomas Chabada' ( https://stackoverflow.com/u/1427786/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving the Automapper Challenge: Mapping a List of Strings to a List of Objects

Are you having trouble using Automapper for mapping between object types? If so, you're not alone. Many C# developers encounter issues when they attempt to map a list of strings to a list of corresponding objects. Let's dive into a specific example of this problem and how we can solve it.

Understanding the Problem

In this scenario, we have two classes:

First Class

Contains a property called ImportantList, which holds a list of strings.

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Second Class

This class contains a property ImportantList, but it holds a list of another class called ImportantListClass.

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The Issue

The challenge arises when we try to map First to Second using Automapper, and we find that the destination's ImportantList remains empty, with Name properties set to null.

Solution: Using ConvertUsing for Proper Mapping

To solve this issue, we need to correctly configure Automapper. The trick lies in using the ConvertUsing method effectively. Let's break down the solution into structured sections.

Step-by-Step Guide to Map Objects

Configuration of Automapper:
We will start by configuring Automapper to know how to convert from ImportantListClass to string and vice versa.

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Creating a Mapper:
After configuring, create a mapper instance that you will use to perform the mappings.

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Mapping Process:
Now, we can create an instance of Second, populate it with ImportantListClass items, and map it to the First object.

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Result

Once the mapping is successfully executed, you'll find that first.ImportantList now contains the strings "Name1" and "Name2".

Here's what’s crucial:

By explicitly telling Automapper how to convert ImportantListClass to a string and back, we ensured proper mapping and data integrity during the transformation.

Conclusion

In conclusion, mapping lists with Automapper might seem daunting at first, especially when dealing with nested objects. However, by applying the correct configuration using ConvertUsing, we can easily map complex structures to fit our needs.

Remember:

Always take care to define how each object type relates to one another, especially when transforming properties that are of different types.

By following this guide, you should be able to overcome similar hurdles in your projects and efficiently use Automapper to streamline your data mapping processes.

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