fix(#107): duplicate db calls in controller

Author: jaredcnance

docs/Errors.md

@@ -31,8 +31,8 @@ public override async Task<IActionResult> PostAsync([FromBody] MyEntity entity)
         return Error(new CustomError("507", "Database is full.", "Theres no more room.", "Sorry."));
 
     if(model.Validations.IsValid == false)
-        return Errors(model.Validations.Select(v => v.GetErrors()));
-        
+        return Errors(model.Validations.GetErrors());
+
     // ...
 }
 ```

src/JsonApiDotNetCore/Controllers/JsonApiController.cs

@@ -64,11 +64,11 @@ public virtual async Task<IActionResult> GetAsync(TId id)
         [HttpGet("{id}/relationships/{relationshipName}")]
         public virtual async Task<IActionResult> GetRelationshipsAsync(TId id, string relationshipName)
         {
-            var relationship = _resourceService.GetRelationshipsAsync(id, relationshipName);
+            var relationship = await _resourceService.GetRelationshipsAsync(id, relationshipName);
             if(relationship == null) 
                 return NotFound();
 
-            return await GetRelationshipAsync(id, relationshipName);
+            return Ok(relationship);
         }
 
         [HttpGet("{id}/{relationshipName}")]

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -51,7 +51,7 @@ public virtual IQueryable<TEntity> Get()
         {
             if(_jsonApiContext.QuerySet?.Fields != null && _jsonApiContext.QuerySet.Fields.Any())
                 return _dbSet.Select(_jsonApiContext.QuerySet?.Fields);
-
+            
             return _dbSet;
         }
 
@@ -92,12 +92,9 @@ public virtual async Task<TEntity> GetAndIncludeAsync(TId id, string relationshi
 
             var result = await Get()
                 .Include(relationshipName)
-                .Where(e => e.Id.Equals(id))
-                .ToListAsync();
-            
-            _logger.LogDebug($"[JADN] Found {result.Count} entity");
+                .SingleOrDefaultAsync(e => e.Id.Equals(id));
 
-            return result.SingleOrDefault();
+            return result;
         }
 
         public virtual async Task<TEntity> CreateAsync(TEntity entity)