feat(*): introduce new IDbContextResolver

this change is focused on improving testability. since an extension method is used to get the dbset from the dbcontext, using a resolver allows us to wrap the extension method call up in a mockable interface

Author: jaredcnance

docs/EntityRepositories.md

@@ -24,16 +24,14 @@ A sample implementation that performs data authorization might look like:
 public class MyAuthorizedEntityRepository : DefaultEntityRepository<MyEntity>
 {
     private readonly ILogger _logger;
-    private readonly AppDbContext _context;
     private readonly IAuthenticationService _authenticationService;
 
-    public MyAuthorizedEntityRepository(AppDbContext context,
+    public MyAuthorizedEntityRepository(
         ILoggerFactory loggerFactory,
         IJsonApiContext jsonApiContext,
         IAuthenticationService authenticationService)
-    : base(context, loggerFactory, jsonApiContext)
-    { 
-        _context = context;
+    : base(loggerFactory, jsonApiContext)
+    {
         _logger = loggerFactory.CreateLogger<MyEntityRepository>();
         _authenticationService = authenticationService;
     }

src/JsonApiDotNetCore/Data/DbContextResolver.cs

@@ -0,0 +1,21 @@
+using System;
+using JsonApiDotNetCore.Extensions;
+using Microsoft.EntityFrameworkCore;
+
+namespace JsonApiDotNetCore.Data
+{
+    public class DbContextResolver : IDbContextResolver
+    {
+        private readonly DbContext _context;
+
+        public DbContextResolver(DbContext context)
+        {
+            _context = context;
+        }
+
+        public DbContext GetContext() => _context;
+
+        public DbSet<TEntity> GetDbSet<TEntity>() where TEntity : class
+            => _context.GetDbSet<TEntity>();
+    }
+}

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
@@ -17,12 +18,19 @@ public class DefaultEntityRepository<TEntity>
         IEntityRepository<TEntity> 
         where TEntity : class, IIdentifiable<int>
     {
+        [Obsolete("DbContext is no longer directly injected into the ctor. Use JsonApiContext.GetDbContextResolver() instead")]
         public DefaultEntityRepository(
             DbContext context,
             ILoggerFactory loggerFactory,
             IJsonApiContext jsonApiContext)
         : base(context, loggerFactory, jsonApiContext)
         { }
+
+        public DefaultEntityRepository(
+            ILoggerFactory loggerFactory,
+            IJsonApiContext jsonApiContext)
+        : base(loggerFactory, jsonApiContext)
+        { }
     }
 
     public class DefaultEntityRepository<TEntity, TId> 
@@ -35,6 +43,7 @@ public class DefaultEntityRepository<TEntity, TId>
         private readonly IJsonApiContext _jsonApiContext;
         private readonly IGenericProcessorFactory _genericProcessorFactory;
 
+        [Obsolete("DbContext is no longer directly injected into the ctor. Use JsonApiContext.GetDbContextResolver() instead")]
         public DefaultEntityRepository(
             DbContext context,
             ILoggerFactory loggerFactory,
@@ -47,6 +56,18 @@ public DefaultEntityRepository(
             _genericProcessorFactory = _jsonApiContext.GenericProcessorFactory;
         }
 
+        public DefaultEntityRepository(
+            ILoggerFactory loggerFactory,
+            IJsonApiContext jsonApiContext)
+        {
+            var contextResolver = jsonApiContext.GetDbContextResolver();
+            _context = contextResolver.GetContext();
+            _dbSet = contextResolver.GetDbSet<TEntity>();
+            _jsonApiContext = jsonApiContext;
+            _logger = loggerFactory.CreateLogger<DefaultEntityRepository<TEntity, TId>>();
+            _genericProcessorFactory = _jsonApiContext.GenericProcessorFactory;
+        }
+
         public virtual IQueryable<TEntity> Get()
         {
             if(_jsonApiContext.QuerySet?.Fields != null && _jsonApiContext.QuerySet.Fields.Any())

src/JsonApiDotNetCore/Data/IDbContextResolver.cs

@@ -0,0 +1,11 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace JsonApiDotNetCore.Data
+{
+    public interface IDbContextResolver
+    {
+        DbContext GetContext();
+        DbSet<TEntity> GetDbSet<TEntity>() 
+            where TEntity : class;
+    }
+}

src/JsonApiDotNetCore/Extensions/IServiceCollectionExtensions.cs

@@ -89,6 +89,7 @@ public static void AddJsonApiInternals(
                 services.AddSingleton<DbContextOptions>(new DbContextOptionsBuilder().Options);
             }
 
+            services.AddScoped<IDbContextResolver, DbContextResolver>();
             services.AddScoped(typeof(IEntityRepository<>), typeof(DefaultEntityRepository<>));
             services.AddScoped(typeof(IEntityRepository<,>), typeof(DefaultEntityRepository<,>));
             services.AddScoped(typeof(IResourceService<>), typeof(EntityResourceService<>));

src/JsonApiDotNetCore/Services/IJsonApiContext.cs

@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using JsonApiDotNetCore.Builders;
 using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Data;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Internal.Generics;
 using JsonApiDotNetCore.Internal.Query;
@@ -24,5 +25,6 @@ public interface IJsonApiContext
         IGenericProcessorFactory GenericProcessorFactory { get; set; }
         Dictionary<AttrAttribute, object> AttributesToUpdate { get; set; }
         Dictionary<RelationshipAttribute, object> RelationshipsToUpdate { get; set; }
+        IDbContextResolver GetDbContextResolver();
     }
 }

src/JsonApiDotNetCore/Services/JsonApiContext.cs

@@ -1,7 +1,9 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using JsonApiDotNetCore.Builders;
 using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Data;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Internal.Generics;
 using JsonApiDotNetCore.Internal.Query;
@@ -13,13 +15,17 @@ namespace JsonApiDotNetCore.Services
     public class JsonApiContext : IJsonApiContext
     {
         private readonly IHttpContextAccessor _httpContextAccessor;
+        private readonly IDbContextResolver _contextResolver;
+
         public JsonApiContext(
+            IDbContextResolver contextResolver,
             IContextGraph contextGraph,
             IHttpContextAccessor httpContextAccessor,
             JsonApiOptions options,
             IMetaBuilder metaBuilder,
             IGenericProcessorFactory genericProcessorFactory)
         {
+            _contextResolver = contextResolver;
             ContextGraph = contextGraph;
             _httpContextAccessor = httpContextAccessor;
             Options = options;
@@ -61,6 +67,8 @@ public IJsonApiContext ApplyContext<T>()
             return this;
         }
 
+        public IDbContextResolver GetDbContextResolver() => _contextResolver;
+
         private PageManager GetPageManager()
         {
             if (Options.DefaultPageSize == 0 && (QuerySet == null || QuerySet.PageQuery.PageSize == 0))