


How Can I Reuse Code for Mapping Single Child Properties to DTOs in EF Core?
Jan 23, 2025 pm 07:41 PMStreamlining DTO Mapping for Single Child Properties in EF Core
Entity Framework Core (EF Core) simplifies object-to-DTO (Data Transfer Object) conversion using expression trees. This works well for child collections, but mapping single child properties can be less intuitive. This article explores solutions for reusing code and efficiently handling this scenario.
The Challenge: Single Child Property Mapping
Directly mapping a single child property to a DTO often requires manual expression additions, leading to repetitive code. Consider this example:
public static Expression<Func<Model, ModelDto>> AsDto => model => new ModelDto { ModelId = model.ModelId, ModelName = model.ModelName, ChildModels = model.ChildModels.AsQueryable().Select(ChildModel.AsDto).ToList(), AnotherChildModel = new AnotherChildModelDto // Manual mapping here { AnotherChildModelId = model.AnotherChildModel.AnotherChildModelId } };
The Solution: Leveraging External Libraries
Several libraries provide elegant solutions by effectively adding a .Select()
-like functionality for single entities, thus enabling code reuse:
1. LINQKit:
LINQKit allows for the expansion of expressions, handling the single-child mapping dynamically.
[Expandable(nameof(AsDtoImpl))] public static ModelDto AsDto(Model model) { _asDtoImpl ??= AsDtoImpl().Compile(); return _asDtoImpl(model); } private static Func<Model, ModelDto> _asDtoImpl; private static Expression<Func<Model, ModelDto>> AsDtoImpl => model => new ModelDto { ModelId = model.ModelId, ModelName = model.ModelName, ChildModels = model.ChildModels.AsQueryable().Select(ChildModel.AsDto).ToList(), AnotherChildModel = model.AnotherChildModel.AsDto() // LINQKit handles this };
2. NeinLinq:
NeinLinq offers a similar approach using lambda injection.
[InjectLambda] public static ModelDto AsDto(Model model) { _asDto ??= AsDto().Compile(); return _asDto(model); } private static Func<Model, ModelDto> _asDto; private static Expression<Func<Model, ModelDto>> AsDto => model => new ModelDto { ModelId = model.ModelId, ModelName = model.ModelName, ChildModels = model.ChildModels.AsQueryable().Select(ChildModel.AsDto).ToList(), AnotherChildModel = model.AnotherChildModel.AsDto() // NeinLinq handles this };
3. DelegateDecompiler:
DelegateDecompiler offers a more concise syntax using computed properties. Note that this approach might not always be suitable depending on the complexity of your mapping.
[Computed] public static ModelDto AsDto(Model model) => new ModelDto { ModelId = model.ModelId, ModelName = model.ModelName, ChildModels = model.ChildModels.AsQueryable().Select(ChildModel.AsDto).ToList(), AnotherChildModel = model.AnotherChildModel.AsDto() // DelegateDecompiler handles this };
Each library requires appropriate setup and configuration to function correctly within your project.
Conclusion:
These libraries offer efficient solutions for reusing code when mapping single child properties to DTOs in EF Core, reducing redundancy and improving maintainability. Choosing the right library depends on project preferences and complexity. The core benefit is a consistent and DRY (Don't Repeat Yourself) approach to DTO mapping.
The above is the detailed content of How Can I Reuse Code for Mapping Single Child Properties to DTOs in EF Core?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

People who study Python transfer to C The most direct confusion is: Why can't you write like Python? Because C, although the syntax is more complex, provides underlying control capabilities and performance advantages. 1. In terms of syntax structure, C uses curly braces {} instead of indentation to organize code blocks, and variable types must be explicitly declared; 2. In terms of type system and memory management, C does not have an automatic garbage collection mechanism, and needs to manually manage memory and pay attention to releasing resources. RAII technology can assist resource management; 3. In functions and class definitions, C needs to explicitly access modifiers, constructors and destructors, and supports advanced functions such as operator overloading; 4. In terms of standard libraries, STL provides powerful containers and algorithms, but needs to adapt to generic programming ideas; 5

Polymorphisms in C are divided into runtime polymorphisms and compile-time polymorphisms. 1. Runtime polymorphism is implemented through virtual functions, allowing the correct method to be called dynamically at runtime. 2. Compilation-time polymorphism is implemented through function overloading and templates, providing higher performance and flexibility.

C destructorsarespecialmemberfunctionsthatautomaticallyreleaseresourceswhenanobjectgoesoutofscopeorisdeleted.1)Theyarecrucialformanagingmemory,filehandles,andnetworkconnections.2)Beginnersoftenneglectdefiningdestructorsfordynamicmemory,leadingtomemo

As a beginner graphical programming for C programmers, OpenGL is a good choice. First, you need to build a development environment, use GLFW or SDL to create a window, load the function pointer with GLEW or glad, and correctly set the context version such as 3.3. Secondly, understand OpenGL's state machine model and master the core drawing process: create and compile shaders, link programs, upload vertex data (VBO), configure attribute pointers (VAO) and call drawing functions. In addition, you must be familiar with debugging techniques, check the shader compilation and program link status, enable the vertex attribute array, set the screen clear color, etc. Recommended learning resources include LearnOpenGL, OpenGLRedBook and YouTube tutorial series. Master the above

STL (Standard Template Library) is an important part of the C standard library, including three core components: container, iterator and algorithm. 1. Containers such as vector, map, and set are used to store data; 2. Iterators are used to access container elements; 3. Algorithms such as sort and find are used to operate data. When selecting a container, vector is suitable for dynamic arrays, list is suitable for frequent insertion and deletion, deque supports double-ended quick operation, map/unordered_map is used for key-value pair search, and set/unordered_set is used for deduplication. When using the algorithm, the header file should be included, and iterators and lambda expressions should be combined. Be careful to avoid failure iterators, update iterators when deleting, and not modify m

Learn C You should start from the following points when playing games: 1. Proficient in basic grammar but do not need to go deep into it, master the basic contents of variable definition, looping, condition judgment, functions, etc.; 2. Focus on mastering the use of STL containers such as vector, map, set, queue, and stack; 3. Learn fast input and output techniques, such as closing synchronous streams or using scanf and printf; 4. Use templates and macros to simplify code writing and improve efficiency; 5. Familiar with common details such as boundary conditions and initialization errors.

C STL is a set of general template classes and functions, including core components such as containers, algorithms, and iterators. Containers such as vector, list, map, and set are used to store data. Vector supports random access, which is suitable for frequent reading; list insertion and deletion are efficient but accessed slowly; map and set are based on red and black trees, and automatic sorting is suitable for fast searches. Algorithms such as sort, find, copy, transform, and accumulate are commonly used to encapsulate them, and they act on the iterator range of the container. The iterator acts as a bridge connecting containers to algorithms, supporting traversal and accessing elements. Other components include function objects, adapters, allocators, which are used to customize logic, change behavior, and memory management. STL simplifies C

std::chrono is used in C to process time, including obtaining the current time, measuring execution time, operation time point and duration, and formatting analysis time. 1. Use std::chrono::system_clock::now() to obtain the current time, which can be converted into a readable string, but the system clock may not be monotonous; 2. Use std::chrono::steady_clock to measure the execution time to ensure monotony, and convert it into milliseconds, seconds and other units through duration_cast; 3. Time point (time_point) and duration (duration) can be interoperable, but attention should be paid to unit compatibility and clock epoch (epoch)
