[.NET Generator] Auto-generate ClientSettings class and IConfiguration-enabled constructors by Copilot · Pull Request #9920 · microsoft/typespec

Copilot · 2026-03-04T20:02:35Z

Original prompt

This section details on the original issue you should resolve

<issue_title>[.NET Generator] Auto-generate ClientSettings class and IConfiguration-enabled constructors for clients</issue_title>
<issue_description>## Overview

Parent issue: Azure/azure-sdk-for-net#55491

The .NET generator should automatically produce IConfiguration-based client construction support for every generated client. This enables developers to configure clients using standard .NET configuration patterns (appsettings.json, environment variables) and register them with dependency injection containers.

Two services have been manually implemented as reference:

The generator should produce these automatically so every client gets configuration support without manual customization.

What the Generator Needs to Produce

Three artifacts per client:

A. `{Client}Settings` class

Extends ClientSettings (from System.ClientModel.Primitives)
Properties derived from the client's primary constructor parameters (excluding credential)
Implements BindCore(IConfigurationSection section) override
Marked [Experimental("SCME0002")]

B. `internal {Client}Options(IConfigurationSection section)` constructor

Calls base(section) — the base options class handles common properties (see Forwarding Binding)
Guards with if (section is null || !section.Exists()) { return; } before binding any properties
Binds each option-specific property from the section
Marked [Experimental("SCME0002")]

C. `public {Client}({Client}Settings settings)` constructor on the client

Delegates to the client's primary constructor (the one with the body implementation) — e.g., (AuthenticationPolicy, Options) or (Uri, AuthenticationPolicy, Options) depending on the client
Creates the authentication policy via AuthenticationPolicy.Create(settings) to pass to the primary constructor
Extracts other properties from settings and maps them to the primary constructor parameters (e.g., settings?.Endpoint, settings?.Options)
Not all clients have a URI parameter — the settings class properties mirror whatever the primary constructor requires
Marked [Experimental("SCME0002")]

How to Determine Settings Properties

The generator should inspect the client's primary public constructor (the one with the body implementation) parameters:

Endpoint/URI parameters (if present) → become Uri? properties on Settings (e.g., VaultUri, Endpoint)
Options parameter → becomes {Client}Options? property on Settings
Credential/AuthenticationPolicy parameter → handled by base ClientSettings.Credential / CredentialProvider, NOT duplicated
Any other non-credential constructor parameters may become settings properties

How to Implement BindCore

`csharp
protected override void BindCore(IConfigurationSection section)
{
if (section is null || !section.Exists())
{
return;
}

// String → use 'is string' pattern match
if (section["Endpoint"] is string endpoint)
{
    Endpoint = new Uri(endpoint);
}

// Options → GetSection + Exists check + internal ctor
IConfigurationSection optionsSection = section.GetSection("Options");
if (optionsSection.Exists())
{
    Options = new {Client}Options(optionsSection);
}

}
`

Key rule: If a configuration segment doesn't exist, bail early — don't set the property. No validation in BindCore. Let the client constructor that receives the settings do all required parameter validation (e.g., Argument.AssertNotNull).

Type Binding Patterns

The generator should use these patterns to bind properties from IConfigurationSection:

Type	Pattern	Example
`string`	`section[name] is string val`	`TenantId = val`
`bool`	`bool.TryParse(section[name], out bool val)`	`DisableChallengeResourceVerification = val`
`Uri`	`Uri.TryCreate(section[name], UriKind.Absolute, out Uri val)`	`RedirectUri = val`
`TimeSpan`	`TimeSpan.TryParse(section[name], out TimeSpan val)`	`NetworkTimeout = val`
`int`	`int.TryParse(section[name], out int val)`	`MaxRetries = val`
`string[]` / `List<string>`	`section.GetSection(name).GetChildren().Where(c => c.Value is not null).Select(c => c.Value!).ToList()`	`AdditionallyAllowedTenants`
Complex object	`section.GetSection(name)` + `.Exists()` + `new Type(section)`	`BrowserCustomization = new BrowserCustomizationOptions(browserSection)`
Custom struct/enum (extensible)	`new TypeName(section[name])` after null check	`Audience = new AppConfigurationAudience(audience)`

For a comprehensive example of bin...

Fixes [.NET Generator] Auto-generate ClientSettings class and IConfiguration-enabled constructors for clients #9842

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

…onfiguration-enabled constructors - Add new ClientSettingsProvider class that generates {Client}Settings classes - Extends ClientSettings from System.ClientModel.Primitives (future type) - Properties for endpoint (Uri?) and options ({Client}Options?) - BindCore override method binding from IConfigurationSection - Marked [Experimental("SCME0002")] - Add IConfigurationSection constructor to ClientOptionsProvider - Internal constructor calling base(section) - Guards with null/Exists check - Binds non-version string properties from configuration - Marked [Experimental("SCME0002")] - Add settings constructor to ClientProvider for root clients with configurable endpoints - Calls primary constructor via this() initializer - Passes endpoint, credential (if auth), and options from settings - Marked [Experimental("SCME0002")] - Add ClientSettingsProvider output in ScmOutputLibrary.BuildClient - Add CSharpType.FromExternalType() public factory method for types not in current NuGet - Update tests to account for new constructors and generated code Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…Settings feature - Use HashSet for O(1) version property name lookup in BuildConfigurationSectionConstructor - Rename local variable from 'propValue' suffix to 'FromConfig' for clarity - Extract IsSettingsConstructor helper in test for maintainability Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

...p/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientSettingsProvider.cs

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/Primitives/CSharpType.cs

JoshLove-msft · 2026-03-05T03:33:08Z

@copilot run Generate.ps1 and investigate any failures.

...rp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientOptionsProvider.cs

…ClientModel 1.9.0 instead of string-based type reference Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

…guard, fix API key credential in settings constructor, fix missing default ctor Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

… fix API key credential extraction, add default ctor, add package dep Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

Copilot · 2026-03-05T04:35:20Z

@copilot run Generate.ps1 and investigate any failures.

Run complete in 04121e3. Generate.ps1 succeeded and the full solution builds with 0 errors. Fixed issues found:

Missing default constructor in ClientOptionsProvider when no API versions (suppressed the auto-generated one)
Invalid CredentialProvider as ApiKeyCredential cast (replaced with settings?.Credential?.Key != null ? new ApiKeyCredential(settings?.Credential?.Key) : null)
Missing non-auth required parameters in settings constructor (e.g. ClientType client, string serviceDeploymentVersion) — ClientSettingsProvider now collects and exposes OtherRequiredParams, generating properties and correct constructor args for them

...rp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClientOptions.cs

…on constructor before guard Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

…uration constructor body Add test coverage for the new configuration-based client initialization features: - ClientOptionsProviderTests: TestConfigurationSectionConstructorBody validates the IConfigurationSection constructor has proper guard statements, version initialization, and config section reading. - ClientProviderTests: TestBuildConstructors_SettingsConstructor validates the settings constructor is public, has correct parameter, uses this() initializer, and has empty body. TestBuildConstructors_NoSettingsConstructor_WhenNoEndpoint validates settings constructor is not generated without an endpoint. - ClientSettingsProviderTests: New test class validating name, base type, properties, BindCore method, experimental attribute, and namespace. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…ests Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

Copilot · 2026-03-11T20:22:23Z

@copilot please address the remaining comments

All 3 remaining comments addressed in be7e618. Added 13 new tests total — all passing with no regressions (248 related tests pass).

Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

JoshLove-msft · 2026-03-11T20:35:22Z

...p/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClientSettings.cs

+
+namespace SampleTypeSpec
+{
+    /// <summary></summary>


@copilot we should include docs and also link to the docs for the ClientSettings type.

IT should follow this pattern - Represents the settings used to configure a SecretClient that can be loaded from an IConfigurationSection.

Added in 0d1d6cf. The generated {Client}Settings class now has a summary doc: Settings for the {Client} client, extending <see cref="ClientSettings"/>.

@copilot please update to this pattern:
Represents the settings used to configure a SecretClient that can be loaded from an IConfigurationSection.

Applied in 272ad43. The generated {Client}Settings class summary now follows the pattern:

/// <summary> Represents the settings used to configure a <see cref="SampleTypeSpecClient"/> that can be loaded from an <see cref="IConfigurationSection"/>. </summary>

…gsProvider Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

…settings used to configure a {Client} that can be loaded from an IConfigurationSection" Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

jorgerangel-msft · 2026-03-11T21:32:23Z

...nt-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientProvider.cs

+                // Add non-auth required parameters from the SAME parameter list (requiredParameters)
+                // to ensure the initializer references the same objects as the constructor signature.
+                string? authParamName = authFields != null
+                    ? (authFields.AuthField.Name != TokenProviderFieldName ? "credential" : authFields.AuthField.AsParameter.Name)


nit: could we move the param name to a constant for consistency with the existing code?

Added SettingsParamName constant in e3998e6.

Applied in e3998e6 — added SettingsParamName constant at line 41 and CredentialParamName constant at line 40, referenced throughout.

jorgerangel-msft · 2026-03-11T21:33:36Z

...nt-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientProvider.cs

+            if (authFields is ApiKeyFields keyFields)
+            {
+                // ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(credential, AuthorizationHeader, prefix?)
+                var credParam = requiredParameters.FirstOrDefault(p => p.Name == "credential");


nit: can we reference the credential string here as a const?

Added CredentialParamName constant and replaced all 4 "credential" string literals in e3998e6.

Applied in e3998e6 — added CredentialParamName constant and replaced all 4 "credential" string literals.

jorgerangel-msft · 2026-03-11T21:40:26Z

...p/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClientSettings.cs

+
+        /// <summary> Binds configuration values from the given section. </summary>
+        /// <param name="section"> The configuration section. </param>
+        protected override void BindCore(IConfigurationSection section)


it would be great if we could test parsing the other supported property types like in https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/identity/Azure.Identity/src/Credentials/DefaultAzureCredentialOptions.cs#L73. Specifically, maybe just the ones outlined in the issue for starters #9842. This can go as a follow up if we don't want to block this pr

@copilot please add the additional test cases

Added bool, int, and TimeSpan TryParse bindings in ec76257, with 4 new tests (TestBindCoreMethod_WithBoolParam, TestBindCoreMethod_WithIntParam, TestBindCoreMethod_WithStringParam, TestProperties_WithMultipleParamTypes). All 1187 tests pass.

JoshLove-msft · 2026-03-11T23:08:01Z

@copilot the Oauth spector tests are failing

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
Failed Invalid [23 ms]
Error Message:
Flows field should not be null
Expected: not null
But was: null

Stack Trace:
at TestProjects.Spector.Tests.Http.Authentication.Oauth2.OAuthTests.<>c.b__1_0(Uri host) in /mnt/vss/_work/1/s/packages/http-client-csharp/generator/TestProjects/Spector.Tests/Http/Authentication/OAuth2/OAuth2Tests.cs:line 66
at TestProjects.Spector.Tests.SpectorTestBase.Test(Func2 test) in /mnt/vss/_work/1/s/packages/http-client-csharp/generator/TestProjects/Spector.Tests/SpectorTestBase.cs:line 17 at TestProjects.Spector.Tests.SpectorTestBase.Test(Func2 test) in /mnt/vss/_work/1/s/packages/http-client-csharp/generator/TestProjects/Spector.Tests/SpectorTestBase.cs:line 30
at NUnit.Framework.Internal.TaskAwaitAdapter.GenericAdapter1.GetResult() at NUnit.Framework.Internal.AsyncToSyncAdapter.Await(Func1 invoke)
at NUnit.Framework.Internal.Commands.TestMethodCommand.RunTestMethod(TestExecutionContext context)
at NUnit.Framework.Internal.Commands.TestMethodCommand.Execute(TestExecutionContext context)
at NUnit.Framework.Internal.Execution.SimpleWorkItem.<>c__DisplayClass4_0.b__0()
at NUnit.Framework.Internal.ContextUtils.<>c__DisplayClass1_0`1.b__0(Object _)

at TestProjects.Spector.Tests.Http.Authentication.Oauth2.OAuthTests.<>c.b__1_0(Uri host) in /mnt/vss/_work/1/s/packages/http-client-csharp/generator/TestProjects/Spector.Tests/Http/Authentication/OAuth2/OAuth2Tests.cs:line 66
at TestProjects.Spector.Tests.SpectorTestBase.Test(Func`2 test) in /mnt/vss/_work/1/s/packages/http-client-csharp/generator/TestProjects/Spector.Tests/SpectorTestBase.cs:line 17
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)

JoshLove-msft · 2026-03-11T23:08:57Z

@copilot you need to run Generate.ps1 and check in the changes

…redential/settings param name constants Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

Copilot · 2026-03-11T23:13:35Z

@copilot the Oauth spector tests are failing

...

Fixed in e3998e6. The _flows field is now private static readonly (required for this() initializer compatibility), so the reflection in OAuth2Tests needed BindingFlags.Static and GetValue(null) instead of BindingFlags.Instance and GetValue(testClient). Updated both the Valid and Invalid test methods.

…ider with tests Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

Copilot · 2026-03-12T00:05:19Z

@copilot the Oauth spector tests are failing

...

The OAuth2 test failure was fixed in e3998e6 — _flows is now static readonly so the reflection needed BindingFlags.Static and GetValue(null). Generate.ps1 confirms all generated code is up to date (no diff after regeneration).

@copilot you need to run Generate.ps1 and check in the changes

Ran Generate.ps1 for all http specs — the generated code is already up to date (no diff). The OAuth2 fix was in the test file (e3998e6), not in generated code. Also added bool/int/TimeSpan TryParse support and tests in ec76257.

github-actions · 2026-03-12T01:01:55Z

No changes needing a change description found.

Initial plan

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Copilot AI assigned Copilot and JoshLove-msft Mar 4, 2026

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Copilot AI changed the title ~~[WIP] Add auto-generation of ClientSettings class and IConfiguration constructors~~ [.NET Generator] Auto-generate ClientSettings class and IConfiguration-enabled constructors Mar 4, 2026

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refactor(http-client-csharp): use typeof(ClientSettings) from System.…

78afaca

…ClientModel 1.9.0 instead of string-based type reference Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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fix(http-client-csharp): add explicit package dependency, fix inline …

9dc25d6

…guard, fix API key credential in settings constructor, fix missing default ctor Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

fix(http-client-csharp): handle non-auth required params in settings,…

04121e3

… fix API key credential extraction, add default ctor, add package dep Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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fix(http-client-csharp): set Version to latest in IConfigurationSecti…

9174c45

…on constructor before guard Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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test: improve property assertion precision in ClientSettingsProviderT…

be7e618

…ests Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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Add see-cref link to settings constructor XML docs

8666c95

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Sort LatestVersionsFields dictionary and add XML docs to ClientSettin…

0d1d6cf

…gsProvider Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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fix: update ClientSettings XML doc to follow pattern "Represents the …

272ad43

…settings used to configure a {Client} that can be loaded from an IConfigurationSection" Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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fix: OAuth2 tests use BindingFlags.Static for _flows field; extract c…

e3998e6

…redential/settings param name constants Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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feat: add bool, int, TimeSpan TryParse bindings in ClientSettingsProv…

ec76257

…ider with tests Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>

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regen

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What the Generator Needs to Produce

A. {Client}Settings class

B. internal {Client}Options(IConfigurationSection section) constructor

C. public {Client}({Client}Settings settings) constructor on the client

How to Determine Settings Properties

How to Implement BindCore

Type Binding Patterns

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Copilot AI commented Mar 4, 2026 •

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A. `{Client}Settings` class

B. `internal {Client}Options(IConfigurationSection section)` constructor

C. `public {Client}({Client}Settings settings)` constructor on the client

Copilot AI commented Mar 12, 2026 •

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