Adding support for DI-enabled destination factories.

[jbogard]

Fixes #4602

[Copilot]

Pull request overview

This PR adds dependency injection support for ConstructUsing by introducing the IDestinationFactory<TSource, TDestination> interface, enabling class-based destination object construction with DI capabilities. This addresses issue #4602 by providing a similar pattern to the existing class-based conditions, resolvers, and converters.

Changes:

• Introduces IDestinationFactory<TSource, TDestination> interface for class-based destination construction
• Adds generic and non-generic ConstructUsing method overloads that accept factory types
• Updates ServiceCollectionExtensions to automatically register IDestinationFactory implementations as transient services

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/AutoMapper/Configuration/IMappingExpressionBase.cs	Defines the new IDestinationFactory<TSource, TDestination> interface and adds ConstructUsing method overloads to support class-based factories
src/AutoMapper/TypeMap.cs	Implements ConstructUsingObjectConstructor method to build expression trees that resolve and invoke destination factories at mapping time
src/AutoMapper/Configuration/TypeMapConfiguration.cs	Adds implementation for generic and non-generic ConstructUsing overloads that register factory types with the type map
src/AutoMapper/ServiceCollectionExtensions.cs	Adds IDestinationFactory<,> to the list of automatically registered AutoMapper types for DI scanning
src/UnitTests/Construction/ClassBasedObjectConstructorTests.cs	Adds comprehensive unit tests covering basic factories, source-aware construction, non-generic usage, and member mapping combinations
src/AutoMapper.DI.Tests/Profiles.cs	Adds test profile and factory implementation demonstrating DI integration
src/AutoMapper.DI.Tests/DependencyTests.cs	Adds integration tests verifying that destination factories work correctly with dependency injection
docs/source/Construction.md	Documents the new class-based destination factory feature with usage examples and DI integration guidance
docs/source/Dependency-injection.md	Updates the list of automatically registered types to include IDestinationFactory and removes redundant condition example

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.

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[Copilot]

using static Expression; and using static ExpressionBuilder; look redundant here because the AutoMapper project already adds these as global static usings (see src/AutoMapper/AutoMapper.csproj <Using ... Static="true"/>). Consider removing the file-level static usings to reduce noise and avoid inconsistencies with the rest of the codebase.

Suggested change

	using static Expression;
	using static ExpressionBuilder;

[Copilot]

The exception messages in ConstructUsingObjectConstructor use .Name for types, which can be ambiguous (same type name in different namespaces) and less actionable when debugging. Consider using FullName (or the Type itself) for objectConstructorType, SourceType, and DestinationType in these error messages.

Suggested change

	throw new InvalidOperationException($"Type '{objectConstructorType.Name}' does not implement IDestinationFactory<{SourceType.Name}, {DestinationType.Name}>");
	}
	var constructMethod = expectedInterface.GetMethod("Construct") ??
	throw new InvalidOperationException($"IDestinationFactory<{SourceType.Name}, {DestinationType.Name}> does not define a 'Construct' method.");
	throw new InvalidOperationException(
	$"Type '{objectConstructorType.FullName ?? objectConstructorType.Name}' does not implement IDestinationFactory<{SourceType.FullName ?? SourceType.Name}, {DestinationType.FullName ?? DestinationType.Name}>");
	}
	var constructMethod = expectedInterface.GetMethod("Construct") ??
	throw new InvalidOperationException(
	$"IDestinationFactory<{SourceType.FullName ?? SourceType.Name}, {DestinationType.FullName ?? DestinationType.Name}> does not define a 'Construct' method.");

[Copilot]

Adding members to the public IMappingExpressionBase<...> interface is a binary/source breaking change for any external implementers. If compatibility is a concern, consider implementing this as extension method(s) (backed by the existing ConstructUsing(Func<...>) overload) or introducing a new interface rather than expanding the existing one.

[Copilot]

This change removes the detailed examples for class-based conditions and dynamic service location from the DI docs, but nothing in the PR description indicates they should be deleted. Unless this was intentional, consider restoring that removed content (or moving it elsewhere) so the DI documentation doesn’t regress.