Add helpers for query params fluent MappingModelBuilder

[biltongza]

This PR adds some helper methods to improve the fluent API syntax when adding query params.

I found that adding query parameters with the fluent API was really tedious, compared to how easy it is to set up a body matcher.

For example, if I wanted to match a request to /api/weather?city=Amsterdam the code might look something like this:

Given(m => m
  .WithRequest(r => r
    .UsingGet()
    .WithPath("/api/weather")
    .WithParams(pb =>pb
      .Add(p => p
        .WithName("city")
        .WithMatchers(mb => mb
          .Add(m => m
            .WithName("ExactMatcher")
            .WithPattern("Amsterdam")
          )
        )
      )
    )
  )
);

Really long and verbose.

With this PR, we can shorten it to:

Given(m => m
  .WithRequest(r => r
    .UsingGet()
    .WithPath("/api/weather")
    .WithParams(pb => pb
      pb.WithParam("city", mb => mb.WithExactMatcher("Amsterdam"))
    )
  )
);

[StefH]

@biltongza
I'm a bit confused. The examples you give are not correct? And I'm not sure your code change is correct. Can you please revisit?

[biltongza]

The example works with the MappingModelBuilder you get from the IWireMockAdminApi. I've added an example.

[StefH]

@biltongza
Would it also make sense to apply the same update to headers and cookies?

[biltongza]

Sure, it probably would make sense for cookies. For headers, there is already a WithHeader(string, string) helper, which under the hood seems to use a wildcard matcher. Would it make sense to have both that helper and this pattern?

[StefH]

Sure, it probably would make sense for cookies. For headers, there is already a WithHeader(string, string) helper, which under the hood seems to use a wildcard matcher. Would it make sense to have both that helper and this pattern?

yes please

[StefH]

@biltongza did you have time to add cookies logic?

[biltongza]

Forgot about this! Will get it in tomorrow :)

[biltongza]

@StefH I pushed the update, wasn't able to test it though. When I try to run the Wiremock.Net.Client app, I get a nice exception from the server:

2026-03-12T18:38:47 fail: WireMock.Net[0]
      HttpStatusCode set to 500 {0}
      System.NotSupportedException: JsonTypeInfo metadata for type 'Newtonsoft.Json.Linq.JArray' was not provided by TypeInfoResolver of type 'WireMock.Net.Json.SourceGenerationContext'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically. The unsupported member type is located on type 'System.Object'. Path: $.BodyAsJson.
       ---> System.NotSupportedException: JsonTypeInfo metadata for type 'Newtonsoft.Json.Linq.JArray' was not provided by TypeInfoResolver of type 'WireMock.Net.Json.SourceGenerationContext'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
         at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
         at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
         at System.Text.Json.WriteStackFrame.InitializePolymorphicReEntry(Type runtimeType, JsonSerializerOptions options)
         at System.Text.Json.Serialization.JsonConverter.ResolvePolymorphicConverter(Object value, JsonTypeInfo jsonTypeInfo, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         --- End of inner exception stack trace ---
         at System.Text.Json.ThrowHelper.ThrowNotSupportedException(WriteStack& state, NotSupportedException ex)
         at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.Serialize(Utf8JsonWriter writer, T& rootValue, Object rootValueBoxed)
         at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonTypeInfo`1 jsonTypeInfo)
         at WireMock.Net.Json.SourceGenerationContext.LogEntryModelSerializeHandler(Utf8JsonWriter writer, LogEntryModel value) in /_/src/dotnet-WireMock.Net/obj/Release/net8.0/System.Text.Json.SourceGeneration/System.Text.Json.SourceGeneration.JsonSourceGenerator/SourceGenerationContext.LogEntryModel.g.cs:line 236
         at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.Serialize(Utf8JsonWriter writer, T& rootValue, Object rootValueBoxed)
         at System.Text.Json.JsonSerializer.WriteString[TValue](TValue& value, JsonTypeInfo`1 jsonTypeInfo)
         at System.Text.Json.JsonSerializer.Serialize[TValue](TValue value, JsonTypeInfo`1 jsonTypeInfo)
         at WireMock.Net.WireMockLogger.DebugRequestResponse(LogEntryModel logEntryModel, Boolean isAdminRequest) in /_/src/dotnet-WireMock.Net/WireMockLogger.cs:line 59
         at WireMock.Owin.WireMockMiddlewareLogger.LogLogEntry(LogEntry entry, Boolean addRequest) in /_/src/WireMock.Net.Minimal/Owin/WireMockMiddlewareLogger.cs:line 56
         at WireMock.Owin.WireMockMiddlewareLogger.LogRequestAndResponse(Boolean logRequest, RequestMessage request, IResponseMessage response, MappingMatcherResult match, MappingMatcherResult partialMatch, Activity activity) in /_/src/WireMock.Net.Minimal/Owin/WireMockMiddlewareLogger.cs:line 38
         at WireMock.Owin.WireMockMiddleware.InvokeInternalAsync(HttpContext ctx) in /_/src/WireMock.Net.Minimal/Owin/WireMockMiddleware.cs:line 169
         at WireMock.Owin.GlobalExceptionMiddleware.InvokeInternalAsync(HttpContext ctx) in /_/src/WireMock.Net.Minimal/Owin/GlobalExceptionMiddleware.cs:line 33

This happened on the latest version (v2.0.0).

I also tried it on v1.2.5 and I got a different error:

2026-03-12T18:40:43 fail: WireMock.Net[0]
      HttpStatusCode set to 500 {0}
      System.NotSupportedException: Serialization and deserialization of 'System.Type' instances is not supported. Path: $.RequestMatchResult.MatchDetails.MatcherType.
       ---> System.NotSupportedException: Serialization and deserialization of 'System.Type' instances is not supported.
         at System.Text.Json.Serialization.Converters.UnsupportedTypeConverter`1.Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Converters.IEnumerableDefaultConverter`2.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonCollectionConverter`2.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         --- End of inner exception stack trace ---
         at System.Text.Json.ThrowHelper.ThrowNotSupportedException(WriteStack& state, NotSupportedException ex)
         at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
         at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.Serialize(Utf8JsonWriter writer, T& rootValue, Object rootValueBoxed)
         at System.Text.Json.JsonSerializer.WriteString[TValue](TValue& value, JsonTypeInfo`1 jsonTypeInfo)
         at System.Text.Json.JsonSerializer.Serialize[TValue](TValue value, JsonSerializerOptions options)
         at WireMock.Net.WireMockLogger.DebugRequestResponse(LogEntryModel logEntryModel, Boolean isAdminRequest) in /_/src/dotnet-WireMock.Net/WireMockLogger.cs:line 58
         at WireMock.Owin.WireMockMiddleware.LogRequest(LogEntry entry, Boolean addRequest) in /_/src/WireMock.Net.Minimal/Owin/WireMockMiddleware.cs:line 362
         at WireMock.Owin.WireMockMiddleware.InvokeInternalCoreAsync(HttpContext ctx, RequestMessage request, Activity activity) in /_/src/WireMock.Net.Minimal/Owin/WireMockMiddleware.cs:line 261
         at WireMock.Owin.WireMockMiddleware.InvokeInternalAsync(HttpContext ctx) in /_/src/WireMock.Net.Minimal/Owin/WireMockMiddleware.cs:line 121
         at WireMock.Owin.GlobalExceptionMiddleware.InvokeInternalAsync(HttpContext ctx) in /_/src/WireMock.Net.Minimal/Owin/GlobalExceptionMiddleware.cs:line 60

[StefH]

@biltongza
Good catch, this is broken in dotnet-WireMock.

It should be fixed here:
#1431

When this is merged to main, you can get latest from main and merge into your branch and test if it works correct.