Struct für Tabellen hinzugefügt, GetLendById-Methode fertiggestellt und IdExits-Methode hinzugefügt

Controllers/LendController.cs

@@ -63,9 +63,13 @@ namespace BuecherwurmAPI.Controllers
 
         //GET api/leihvorgang/{id}
         [HttpGet("{id}")]
-        public ActionResult<Lend> LendById(int id)
+        public ActionResult<Lend> LendById(long id)
         {
             var lend = _repository.GetLendById(id);
+            if (!_repository.IdExits(Tables.Table.Lends, id))
+            {
+                return NotFound();
+            }
             return Ok(lend);
         }
 
@@ -73,11 +77,6 @@ namespace BuecherwurmAPI.Controllers
         [HttpPatch("{id}")]
         public ActionResult LendPatchById(int id, JsonPatchDocument<Lend> patchDocument)
         {
-            var lend = _repository.GetLendById(id);
-            if (lend == null)
-            {
-                return NotFound();
-            }
             return Ok();
         }
     }

Data/IRepository.cs

@@ -1,11 +1,13 @@
 using System.Collections.Generic;
 using BuecherwurmAPI.Models;
+using Microsoft.EntityFrameworkCore.Metadata.Conventions;
 
 namespace BuecherwurmAPI.Data
 {
     public interface IRepository
     {
         IEnumerable<Lend> GetAllLends();
-        Lend GetLendById(int id);
+        Lend GetLendById(long id);
+        bool IdExits(string table, long id);
     }
 }

Data/Repository.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using BuecherwurmAPI.Models;
 using Microsoft.Data.Sqlite;
+using Microsoft.VisualBasic.CompilerServices;
 
 namespace BuecherwurmAPI.Data
 {
@@ -16,6 +17,33 @@ namespace BuecherwurmAPI.Data
             _dbConnection.Open();
         }
 
+        public bool IdExits(string table, long id)
+        {
+            using (var command = _dbConnection.CreateCommand())
+            {
+                var com = _dbConnection.CreateCommand();
+
+                com.Parameters.Add(new SqliteParameter("@Id", SqliteType.Integer)).Value = id;
+                
+                // Certain parts of the query can't be filled with variables for security reasons.
+                switch (table)
+                {
+                    case Tables.Table.Lends: 
+                        com.CommandText = @"SELECT EXISTS(SELECT 0 FROM Lends WHERE Id = @Id)";
+                        break;
+                }
+                
+                var dr = com.ExecuteReader();
+                
+                long result = 0;
+                while (dr.Read())
+                {
+                    result = (long) dr[0];
+                }
+                return result != 0;
+            }
+        }
+
         public IEnumerable<Lend> GetAllLends()
         {
             var lends = new List<Lend>();
@@ -28,14 +56,14 @@ namespace BuecherwurmAPI.Data
                 
                 while (dataReader.Read())
                 {
-                    var returned = (long) dataReader["Returned"] == 0;
+                    var returned = (long) dataReader["Returned"] == 1;
                     
                     lends.Add(new Lend
                     {
                         Id = (long) dataReader["Id"],
                         Customer = (string) dataReader["Customer"],
                         ItemId = (long) dataReader["ItemId"],
-                        Returned = !returned,
+                        Returned = returned,
                         ReturnDate = DateTime.Parse((string)dataReader["ReturnDate"])
                     });
                 }
@@ -43,9 +71,30 @@ namespace BuecherwurmAPI.Data
             return lends;
         }
 
-        public Lend GetLendById(int id)
+        public Lend GetLendById(long id)
         {
-            return new Lend{Id = 1, Customer = "Nek0", ItemId = 1337, Returned = false, ReturnDate = DateTime.Now};
+            using (var command = _dbConnection.CreateCommand())
+            {
+                command.Parameters.Add(new SqliteParameter("@id", SqliteType.Integer)).Value = id;
+                command.CommandText = @"SELECT * FROM Lends WHERE Id = @id";
+                var dataReader = command.ExecuteReader();
+
+                while (dataReader.Read())
+                {
+                    var returned = (long) dataReader["Returned"] == 1;
+
+                    var lend = new Lend
+                    {
+                        Id = (long) dataReader["Id"],
+                        Customer = (string) dataReader["Customer"],
+                        ItemId = (long) dataReader["ItemId"],
+                        Returned = returned,
+                        ReturnDate = DateTime.Parse((string) dataReader["ReturnDate"])
+                    };
+                    return lend;
+                }
+            }
+            return null;
         }
     }
 }

Data/Tables.cs

@@ -0,0 +1,10 @@
+namespace BuecherwurmAPI.Data
+{
+    public static class Tables
+    {
+        public struct Table
+        {
+            public const string Lends = "Lends";
+        }
+    }
+}