Скачать или смотреть Transforming a Flattened Object into a Nested Collection with AutoMapper

Learn how to efficiently map a `flattened list` of objects into a nested collection using AutoMapper in C-. This guide outlines key steps and a clear code example that addresses common pitfalls.
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Mapping Flattened Object's Properties as Collection

In a world of data manipulation, developers often face challenges related to object mapping and transformation. One such challenge is converting a flattened list of objects into a structured nested collection. This scenario is prevalent when working with object-oriented programming in C-, especially utilizing libraries like AutoMapper for streamlined mapping capabilities. In this guide, we’ll explore a concrete example of transforming flattened properties into a nested collection.

The Problem

Imagine you have a SourceObject class with multiple flattened image properties. Your goal is to map these properties into a TargetObject, which comprises a list of TargetObjectImage instances. Here’s what your source and target objects look like:

Source Object

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Target Object

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In this case, the TargetObject needs to contain a collection of images extracted from the SourceObject. However, it’s crucial to note that not all image properties might be populated. If an image property is empty, it shouldn't be included in the nested collection.

The Solution

To address the aforementioned challenge, we can take advantage of AutoMapper by defining a custom resolver. This will help us map the relevant image properties from the SourceObject to the TargetObject appropriately.

Step 1: Create a Custom Resolver

A custom resolver will enable us to define the logic for extracting the image URIs from the SourceObject. Here’s the code for the resolver:

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Step 2: Define the Mapping Profile

In this step, we will create a mapping profile that configures AutoMapper to map SourceObject to TargetObject while utilizing our custom resolver for the Images collection:

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Explanation of the Mapping Configuration

ForMember: This method allows you to specify that you're mapping from one property to another.

MapFrom: This indicates how AutoMapper should map the source property to the destination.

CustomResolver: Here, we indicate that the custom mapping logic is to be applied for generating the Images collection.

Conclusion

By implementing this approach, you can seamlessly transform a flattened list of properties into a nested collection. The use of a custom resolver enables you to incorporate necessary logic, such as excluding empty properties, ensuring a clean mapping process.

If you're working with AutoMapper and facing similar challenges, consider structuring your code in the way outlined above. The combination of clear mapping and a custom resolver can enhance the manageability and readability of your codebase.

With this guide, you should now be equipped to tackle the problem of mapping flattened properties as collections with confidence!