Adding support for DI-enabled destination factories. by jbogard · Pull Request #4603 · LuckyPennySoftware/AutoMapper

jbogard · 2026-02-20T23:07:13Z

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

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

src/AutoMapper/TypeMap.cs

src/AutoMapper/Configuration/IMappingExpressionBase.cs

docs/source/Construction.md

Copilot

Pull request overview

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

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

src/AutoMapper/TypeMap.cs

docs/source/Dependency-injection.md

docs/source/Construction.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

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

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-02-21T16:13:30Z

src/AutoMapper/TypeMap.cs

+using static Expression;
+using static ExpressionBuilder;


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 · 2026-02-21T16:13:31Z

src/AutoMapper/TypeMap.cs

+            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.");


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 · 2026-02-21T16:13:31Z

src/AutoMapper/Configuration/IMappingExpressionBase.cs

+    /// Supply a custom object constructor type for instantiating the destination type with dependency injection support
+    /// </summary>
+    /// <remarks>Not used for LINQ projection (ProjectTo).</remarks>
+    /// <typeparam name="TConstructor">Constructor type implementing IDestinationFactory&lt;TSource, TDestination&gt;</typeparam>
+    /// <returns>Itself</returns>
+    TMappingExpression ConstructUsing<TConstructor>() where TConstructor : IDestinationFactory<TSource, TDestination>;
+    /// <summary>
+    /// Supply a custom object constructor type for instantiating the destination type with dependency injection support.
+    /// Used when the constructor type is not known at compile-time.
+    /// </summary>
+    /// <remarks>Not used for LINQ projection (ProjectTo).</remarks>
+    /// <param name="objectConstructorType">Constructor type implementing IDestinationFactory</param>
+    void ConstructUsing(Type objectConstructorType);


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 · 2026-02-21T16:13:31Z

docs/source/Dependency-injection.md

 ## Low level API-s

 AutoMapper supports the ability to construct [Custom Value Resolvers](Custom-value-resolvers.html), [Custom Type Converters](Custom-type-converters.html), [Value Converters](Value-converters.html), and [Class-based Conditions](Conditional-mapping.html#class-based-conditions) using static service location:

 ```c#
 var configuration = new MapperConfiguration(cfg =>
 {
    cfg.ConstructServicesUsing(ObjectFactory.GetInstance);

    cfg.CreateMap<Source, Destination>();
 }, loggerFactory);
 ```

 ### Automatic Class Registration

 When using `AddAutoMapper`, AutoMapper will automatically register implementations of the following types as `ServiceLifetime.Transient` from the specified assemblies:

 - `IValueResolver<TSource, TDestination, TDestMember>`
 - `IMemberValueResolver<TSource, TDestination, TSourceMember, TDestMember>`
 - `ITypeConverter<TSource, TDestination>`
 - `IValueConverter<TSourceMember, TDestinationMember>`
+- `IDestinationFactory<TSource, TDestination>`
 - `ICondition<TSource, TDestination, TMember>`
 - `IPreCondition<TSource, TDestination>`
 - `IMappingAction<TSource, TDestination>`

-This allows you to use class-based conditions with dependency injection:
-
-```c#
-public class MyCondition : ICondition<Source, Destination, int>
-{
-    private readonly IMyService _myService;
-
-    public MyCondition(IMyService myService)
-    {
-        _myService = myService;
-    }
-
-    public bool Evaluate(Source source, Destination destination, int sourceMember, 
-                        int destMember, ResolutionContext context)
-    {
-        return _myService.ShouldMap(sourceMember);
-    }
-}
-
-public class ConditionProfile : Profile
-{
-    public ConditionProfile()
-    {
-        CreateMap<Source, Destination>()
-            .ForMember(d => d.Value, o =>
-            {
-                o.Condition<MyCondition>();
-                o.MapFrom(s => s.Value);
-            });
-    }
-}
-
-// In Startup.cs / Program.cs:
-services.AddTransient<IMyService, MyService>();
-services.AddAutoMapper(cfg => { }, typeof(ConditionProfile).Assembly);
-```
-
-Or dynamic service location, to be used in the case of instance-based containers (including child/nested containers):
-
-```c#
-var mapper = new Mapper(configuration, childContainer.GetInstance);
-
-var dest = mapper.Map<Source, Destination>(new Source { Value = 15 });
-```
-
 ## Queryable Extensions


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.

docs/source/Construction.md

Updated [AutoMapper](https://github.com/LuckyPennySoftware/AutoMapper) from 16.0.0 to 16.1.1. <details> <summary>Release notes</summary> _Sourced from [AutoMapper's releases](https://github.com/LuckyPennySoftware/AutoMapper/releases)._ ## 16.1.1 ## What's Changed * Better async handling of license validation; fixes #4612 by @jbogard in LuckyPennySoftware/AutoMapper#4613 * More artifacts for builds (test results and SBOM) by @jbogard in LuckyPennySoftware/AutoMapper#4615 * Update Microsoft.Sbom.DotNetTool to 4.1.5 by @jbogard in LuckyPennySoftware/AutoMapper#4616 ## Security Fixed an issue where certain cyclic or self-referential object graphs could trigger uncontrolled recursion during mapping, potentially resulting in stack exhaustion and denial of service. Applications that process untrusted or attacker-controlled object graphs through affected mapping paths may be impacted. Users should upgrade to this release. Security advisory: GHSA-rvv3-g6hj-g44x Thanks to @bluefossa for responsibly disclosing this issue. **Full Changelog**: LuckyPennySoftware/AutoMapper@v16.1.0...v16.1.1 ## 16.1.0 ## What's Changed * Add Debug and Release build configurations to slnx by @Copilot in LuckyPennySoftware/AutoMapper#4590 * Migrating to slnx by @jbogard in LuckyPennySoftware/AutoMapper#4589 * Allow disabling of polymorphic LINQ mapping by @jbogard in LuckyPennySoftware/AutoMapper#4596 * Fix duplicate BOM in ServiceCollectionExtensions.cs by @Copilot in LuckyPennySoftware/AutoMapper#4600 * Fix review feedback: double semicolon, DI condition integration test, docs example by @Copilot in LuckyPennySoftware/AutoMapper#4601 * Adding DI-enabled conditions and pre-conditions; updated docs accordi… by @jbogard in LuckyPennySoftware/AutoMapper#4599 * Adding support for DI-enabled destination factories. by @jbogard in LuckyPennySoftware/AutoMapper#4603 * Correctly converting nullables for MapAtRuntime; fixes #4597 by @jbogard in LuckyPennySoftware/AutoMapper#4604 * Correctly handling consecutive uppercase characters; fixes #4593 by @jbogard in LuckyPennySoftware/AutoMapper#4605 * Wrapping the exception to provide better feedback to the user; fixes … by @jbogard in LuckyPennySoftware/AutoMapper#4606 * Fixing bug around order of open generic registration by @jbogard in LuckyPennySoftware/AutoMapper#4607 * Adding perpetual licensing by @jbogard in LuckyPennySoftware/AutoMapper#4608 ## New Contributors * @Copilot made their first contribution in LuckyPennySoftware/AutoMapper#4590 **Full Changelog**: LuckyPennySoftware/AutoMapper@v16.0.0...v16.1.0 Commits viewable in [compare view](LuckyPennySoftware/AutoMapper@v16.0.0...v16.1.1). </details> [![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=AutoMapper&package-manager=nuget&previous-version=16.0.0&new-version=16.1.1)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- <details> <summary>Dependabot commands and options</summary> <br /> You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore <dependency name> major version` will close this group update PR and stop Dependabot creating any more for the specific dependency's major version (unless you unignore this specific dependency's major version or upgrade to it yourself) - `@dependabot ignore <dependency name> minor version` will close this group update PR and stop Dependabot creating any more for the specific dependency's minor version (unless you unignore this specific dependency's minor version or upgrade to it yourself) - `@dependabot ignore <dependency name>` will close this group update PR and stop Dependabot creating any more for the specific dependency (unless you unignore this specific dependency or upgrade to it yourself) - `@dependabot unignore <dependency name>` will remove all of the ignore conditions of the specified dependency - `@dependabot unignore <dependency name> <ignore condition>` will remove the ignore condition of the specified dependency and ignore conditions You can disable automated security fix PRs for this repo from the [Security Alerts page](https://github.com/mlapaglia/OpenAlprWebhookProcessor/network/alerts). </details> Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

github-actions · 2026-03-29T00:22:01Z

This pull request has been automatically locked since there has not been any recent activity after it was closed.

Adding support for DI-enabled destination factories.

a96752e

Fixes #4602

jbogard linked an issue Feb 20, 2026 that may be closed by this pull request

Enable DI for ConstructUsing #4602

Closed

jbogard requested a review from Copilot February 20, 2026 23:07

Copilot started reviewing on behalf of jbogard February 20, 2026 23:07 View session

Fixing tests

bc730bc

Copilot AI reviewed Feb 20, 2026

View reviewed changes

Fixing doc notes

0bcbc6e

jbogard requested a review from Copilot February 20, 2026 23:19

Copilot started reviewing on behalf of jbogard February 20, 2026 23:19 View session

Copilot AI reviewed Feb 20, 2026

View reviewed changes

src/AutoMapper/TypeMap.cs Show resolved Hide resolved

src/AutoMapper/TypeMap.cs Outdated Show resolved Hide resolved

docs/source/Dependency-injection.md Show resolved Hide resolved

docs/source/Construction.md Show resolved Hide resolved

jbogard and others added 2 commits February 20, 2026 18:28

Update TypeMap.cs

222353d

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Fixing docs

8e5248b

jbogard requested a review from Copilot February 21, 2026 16:06

Copilot started reviewing on behalf of jbogard February 21, 2026 16:06 View session

Copilot AI reviewed Feb 21, 2026

View reviewed changes

jbogard merged commit fd06570 into main Feb 21, 2026
10 checks passed

jbogard deleted the 4602-enable-di-for-constructusing branch February 21, 2026 16:21

jbogard added this to the 16.1.0 milestone Feb 21, 2026

jbogard added the Feature label Feb 21, 2026

dependabot bot mentioned this pull request Mar 22, 2026

Bump the nuget group with 1 update cmu-sei/GHOSTS#605

Merged

This was referenced Mar 23, 2026

Bump AutoMapper from 15.0.0 to 16.1.1 osisdie/dotnet-webapi-cqrs-boilerplate#4

Merged

Bump AutoMapper from 13.0.1 to 16.1.1 Gramli/WeatherApi#24

Open

deps: Bump the production-dependencies group with 19 updates guelfi/Batuara.net#30

Open

github-actions bot locked as resolved and limited conversation to collaborators Mar 29, 2026

Conversation

jbogard commented Feb 20, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Copilot AI Feb 21, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 21, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 21, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 21, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

github-actions bot commented Mar 29, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants