Add [TraxQueryModel] support for GraphQL entity queries

src/Trax.Api.GraphQL/Configuration/GraphQLConfiguration.cs

@@ -0,0 +1,22 @@
+namespace Trax.Api.GraphQL.Configuration;
+
+/// <summary>
+/// Holds the resolved configuration for the Trax GraphQL schema,
+/// including discovered query model registrations.
+/// </summary>
+public class GraphQLConfiguration
+{
+    public IReadOnlyList<QueryModelRegistration> ModelRegistrations { get; }
+
+    /// <summary>
+    /// Tracks which namespace base types and namespace fields have been registered
+    /// across type modules to prevent duplicate registrations. Populated at runtime
+    /// by <c>TrainTypeModule</c> and <c>QueryModelTypeModule</c>.
+    /// </summary>
+    internal HashSet<string> RegisteredNamespaceTypes { get; } = new(StringComparer.Ordinal);
+
+    public GraphQLConfiguration(IReadOnlyList<QueryModelRegistration> modelRegistrations)
+    {
+        ModelRegistrations = modelRegistrations;
+    }
+}

src/Trax.Api.GraphQL/Configuration/QueryModelRegistration.cs

@@ -0,0 +1,13 @@
+using Trax.Effect.Attributes;
+
+namespace Trax.Api.GraphQL.Configuration;
+
+/// <summary>
+/// Represents a discovered entity type marked with <see cref="TraxQueryModelAttribute"/>
+/// and its owning DbContext type.
+/// </summary>
+public record QueryModelRegistration(
+    Type EntityType,
+    Type DbContextType,
+    TraxQueryModelAttribute Attribute
+);

src/Trax.Api.GraphQL/Configuration/TraxGraphQLBuilder/TraxGraphQLBuilder.Build.cs

@@ -0,0 +1,35 @@
+using System.Reflection;
+using Microsoft.EntityFrameworkCore;
+using Trax.Effect.Attributes;
+
+namespace Trax.Api.GraphQL.Configuration.TraxGraphQLBuilder;
+
+public partial class TraxGraphQLBuilder
+{
+    internal GraphQLConfiguration Build()
+    {
+        var modelRegistrations = new List<QueryModelRegistration>();
+
+        foreach (var dbContextType in DbContextTypes)
+        {
+            var dbSetProps = dbContextType
+                .GetProperties(BindingFlags.Public | BindingFlags.Instance)
+                .Where(p =>
+                    p.PropertyType.IsGenericType
+                    && p.PropertyType.GetGenericTypeDefinition() == typeof(DbSet<>)
+                );
+
+            foreach (var prop in dbSetProps)
+            {
+                var entityType = prop.PropertyType.GetGenericArguments()[0];
+                var attr = entityType.GetCustomAttribute<TraxQueryModelAttribute>();
+                if (attr is null)
+                    continue;
+
+                modelRegistrations.Add(new QueryModelRegistration(entityType, dbContextType, attr));
+            }
+        }
+
+        return new GraphQLConfiguration(modelRegistrations);
+    }
+}

src/Trax.Api.GraphQL/Configuration/TraxGraphQLBuilder/TraxGraphQLBuilder.DbContext.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace Trax.Api.GraphQL.Configuration.TraxGraphQLBuilder;
+
+public partial class TraxGraphQLBuilder
+{
+    /// <summary>
+    /// Registers a DbContext whose <c>DbSet&lt;T&gt;</c> entities marked with
+    /// <c>[TraxQueryModel]</c> will be automatically exposed as paginated,
+    /// filterable, sortable GraphQL queries under <c>discover</c>.
+    /// </summary>
+    /// <typeparam name="TDbContext">
+    /// The DbContext type containing DbSet properties for the entities to expose.
+    /// Must be registered in DI (e.g. via <c>AddDbContextFactory</c> or <c>AddDbContext</c>).
+    /// </typeparam>
+    public TraxGraphQLBuilder AddDbContext<TDbContext>()
+        where TDbContext : DbContext
+    {
+        DbContextTypes.Add(typeof(TDbContext));
+        return this;
+    }
+}

src/Trax.Api.GraphQL/Configuration/TraxGraphQLBuilder/TraxGraphQLBuilder.cs

@@ -0,0 +1,21 @@
+using System.ComponentModel;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Trax.Api.GraphQL.Configuration.TraxGraphQLBuilder;
+
+/// <summary>
+/// Builder for configuring the Trax GraphQL schema, including DbContext-based
+/// model query registration.
+/// </summary>
+public partial class TraxGraphQLBuilder
+{
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    internal IServiceCollection Services { get; }
+
+    internal List<Type> DbContextTypes { get; } = [];
+
+    public TraxGraphQLBuilder(IServiceCollection services)
+    {
+        Services = services;
+    }
+}

src/Trax.Api.GraphQL/Extensions/GraphQLServiceExtensions.cs

@@ -1,7 +1,10 @@
+using HotChocolate.Data;
 using HotChocolate.Types;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 using Trax.Api.Extensions;
+using Trax.Api.GraphQL.Configuration;
+using Trax.Api.GraphQL.Configuration.TraxGraphQLBuilder;
 using Trax.Api.GraphQL.Errors;
 using Trax.Api.GraphQL.Hooks;
 using Trax.Api.GraphQL.Mutations;
@@ -20,18 +23,31 @@ public static class GraphQLServiceExtensions
     private const string SchemaName = "trax";
 
     /// <summary>
-    /// Registers the Trax GraphQL schema on a named HotChocolate server ("trax").
-    /// This avoids conflicts with a consumer's own default GraphQL schema.
-    /// Only trains annotated with <c>[TraxQuery]</c> or <c>[TraxMutation]</c> get typed operations generated.
+    /// Registers the Trax GraphQL schema on a named HotChocolate server ("trax")
+    /// with support for configuring DbContext-based model queries.
     /// </summary>
-    public static IServiceCollection AddTraxGraphQL(this IServiceCollection services)
+    /// <example>
+    /// <code>
+    /// services.AddTraxGraphQL(graphql => graphql
+    ///     .AddDbContext&lt;GameDbContext&gt;());
+    /// </code>
+    /// </example>
+    public static IServiceCollection AddTraxGraphQL(
+        this IServiceCollection services,
+        Func<TraxGraphQLBuilder, TraxGraphQLBuilder> configure
+    )
     {
         if (!services.Any(sd => sd.ServiceType == typeof(TraxMarker)))
             throw new InvalidOperationException(
                 "AddTraxGraphQL() requires AddTrax() to be called first. "
                     + "Call services.AddTrax(trax => ...) before services.AddTraxGraphQL()."
             );
 
+        var builder = new TraxGraphQLBuilder(services);
+        configure(builder);
+        var config = builder.Build();
+        services.AddSingleton(config);
+
         services.AddTraxApi();
         services.AddSingleton<TrainTypeModule>();
         services.AddTransient<GraphQLSubscriptionHook>();
@@ -40,7 +56,8 @@ public static IServiceCollection AddTraxGraphQL(this IServiceCollection services
             .AddSingleton<ITrainLifecycleHookFactory>(sp =>
                 sp.GetRequiredService<GraphQLSubscriptionHookFactory>()
             );
-        services
+
+        var graphqlBuilder = services
             .AddGraphQLServer(SchemaName)
             .AddQueryType<RootQuery>()
             .AddMutationType<RootMutation>()
@@ -52,6 +69,34 @@ public static IServiceCollection AddTraxGraphQL(this IServiceCollection services
             .AddErrorFilter<TraxErrorFilter>()
             .AddInMemorySubscriptions();
 
+        if (config.ModelRegistrations.Count > 0)
+        {
+            services.AddSingleton<QueryModelTypeModule>();
+            graphqlBuilder.AddTypeModule<QueryModelTypeModule>();
+
+            // Register DiscoverQueries base type and discover field on RootQuery.
+            // TrainTypeModule will skip creating these when it detects model registrations.
+            graphqlBuilder.AddType(new ObjectType<DiscoverQueries>());
+            graphqlBuilder.AddTypeExtension(
+                new ObjectTypeExtension(d =>
+                {
+                    d.Name("RootQuery");
+                    d.Field("discover")
+                        .Type<ObjectType<DiscoverQueries>>()
+                        .Resolve(_ => new DiscoverQueries());
+                })
+            );
+
+            if (config.ModelRegistrations.Any(r => r.Attribute.Filtering))
+                graphqlBuilder.AddFiltering();
+
+            if (config.ModelRegistrations.Any(r => r.Attribute.Sorting))
+                graphqlBuilder.AddSorting();
+
+            if (config.ModelRegistrations.Any(r => r.Attribute.Projection))
+                graphqlBuilder.AddProjections();
+        }
+
         // If a broadcaster receiver is registered (via UseBroadcaster()),
         // wire up the GraphQL handler so remote lifecycle events are forwarded
         // to HotChocolate subscriptions.
@@ -63,6 +108,14 @@ public static IServiceCollection AddTraxGraphQL(this IServiceCollection services
         return services;
     }
 
+    /// <summary>
+    /// Registers the Trax GraphQL schema on a named HotChocolate server ("trax").
+    /// This avoids conflicts with a consumer's own default GraphQL schema.
+    /// Only trains annotated with <c>[TraxQuery]</c> or <c>[TraxMutation]</c> get typed operations generated.
+    /// </summary>
+    public static IServiceCollection AddTraxGraphQL(this IServiceCollection services) =>
+        services.AddTraxGraphQL(builder => builder);
+
     /// <summary>
     /// Maps the Trax GraphQL endpoint at the specified route prefix.
     /// Uses a named schema so it coexists with other HotChocolate schemas

src/Trax.Api.GraphQL/Trax.Api.GraphQL.csproj

@@ -18,6 +18,8 @@
 
   <ItemGroup>
     <FrameworkReference Include="Microsoft.AspNetCore.App" />
-    <PackageReference Include="HotChocolate.AspNetCore" Version="14.*" />
+    <PackageReference Include="HotChocolate.AspNetCore" Version="15.*" />
+    <PackageReference Include="HotChocolate.Data" Version="15.*" />
+    <PackageReference Include="HotChocolate.Data.EntityFramework" Version="15.*" />
   </ItemGroup>
 </Project>