Add dependency Injection

Controllers/GerbilsController.cs

@@ -8,11 +8,11 @@ namespace GerbilManager.Controllers
     [Route("gerbils")]
     public class GerbilsController : ControllerBase
     {
-        private readonly InMemGerbilRepository repository;
+        private readonly IGerbilRepository repository;
 
-        public GerbilsController()
+        public GerbilsController(IGerbilRepository repo)
         {
-            repository = new InMemGerbilRepository();
+            this.repository = repo;
         }
 
         //GET /gerbils
@@ -22,5 +22,18 @@ namespace GerbilManager.Controllers
             var items = repository.GetGerbils();
             return items;
         }
+
+        //GET /gerbils
+        [HttpGet("{id}")]
+        public ActionResult<Gerbil> GetGerbil(Guid id)
+        {
+            var item = repository.GetGerbil(id);
+
+            if(item is null)
+            {
+                return NotFound();
+            }
+            return item;
+        }
     }
 }