i had to.

.vs/ProjectSettings.json

@@ -1,3 +0,0 @@
-{
-  "CurrentProjectSetting": null
-}

BuecherwurmAPI.csproj

@@ -4,5 +4,10 @@
     <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="7.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.4" />
+  </ItemGroup>
+
 
 </Project>

Models/Lend.cs

@@ -10,4 +10,4 @@ namespace BuecherwurmAPI.Models
         public string Customer { get; set;  }
         public bool Returned { get; set; }
     }
-}
+} 

Properties/launchSettings.json

@@ -12,7 +12,7 @@
     "IIS Express": {
       "commandName": "IISExpress",
       "launchBrowser": true,
-      "launchUrl": "weatherforecast",
+      "launchUrl": "api",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
       }
@@ -20,7 +20,7 @@
     "BuecherwurmAPI": {
       "commandName": "Project",
       "launchBrowser": true,
-      "launchUrl": "weatherforecast",
+      "launchUrl": "api",
       "applicationUrl": "https://localhost:5001;http://localhost:5000",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"

Startup.cs

@@ -2,6 +2,8 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
+using AutoMapper;
+using BuecherwurmAPI.Data;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.HttpsPolicy;
@@ -26,6 +28,13 @@ namespace BuecherwurmAPI
         public void ConfigureServices(IServiceCollection services)
         {
             services.AddControllers();
+            
+            // Adds a service that is created once per connection.
+            // It takes an interface and a specific implementation.
+            // That allows to swap the implementation easily.
+            services.AddScoped<ILendRepo, MockLendRepo>();
+
+            services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

obj/BuecherwurmAPI.csproj.nuget.dgspec.json

@@ -1,67 +0,0 @@
-{
-  "format": 1,
-  "restore": {
-    "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj": {}
-  },
-  "projects": {
-    "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj": {
-      "version": "1.0.0",
-      "restore": {
-        "projectUniqueName": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj",
-        "projectName": "BuecherwurmAPI",
-        "projectPath": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj",
-        "packagesPath": "/home/js/.nuget/packages/",
-        "outputPath": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/obj/",
-        "projectStyle": "PackageReference",
-        "configFilePaths": [
-          "/home/js/.nuget/NuGet/NuGet.Config"
-        ],
-        "originalTargetFrameworks": [
-          "netcoreapp3.1"
-        ],
-        "sources": {
-          "https://api.nuget.org/v3/index.json": {}
-        },
-        "frameworks": {
-          "netcoreapp3.1": {
-            "projectReferences": {}
-          }
-        },
-        "warningProperties": {
-          "warnAsError": [
-            "NU1605"
-          ]
-        }
-      },
-      "frameworks": {
-        "netcoreapp3.1": {
-          "imports": [
-            "net461",
-            "net462",
-            "net47",
-            "net471",
-            "net472",
-            "net48"
-          ],
-          "assetTargetFallback": true,
-          "warn": true,
-          "downloadDependencies": [
-            {
-              "name": "Microsoft.AspNetCore.App.Ref",
-              "version": "[3.1.2, 3.1.2]"
-            }
-          ],
-          "frameworkReferences": {
-            "Microsoft.AspNetCore.App": {
-              "privateAssets": "none"
-            },
-            "Microsoft.NETCore.App": {
-              "privateAssets": "all"
-            }
-          },
-          "runtimeIdentifierGraphPath": "/usr/share/dotnet/sdk/3.1.300/RuntimeIdentifierGraph.json"
-        }
-      }
-    }
-  }
-}

obj/BuecherwurmAPI.csproj.nuget.g.props

@@ -1,15 +0,0 @@
-<?xml version="1.0" encoding="utf-8" standalone="no"?>
-<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup Condition=" '$(ExcludeRestorePackageImports)' != 'true' ">
-    <RestoreSuccess Condition=" '$(RestoreSuccess)' == '' ">True</RestoreSuccess>
-    <RestoreTool Condition=" '$(RestoreTool)' == '' ">NuGet</RestoreTool>
-    <ProjectAssetsFile Condition=" '$(ProjectAssetsFile)' == '' ">$(MSBuildThisFileDirectory)project.assets.json</ProjectAssetsFile>
-    <NuGetPackageRoot Condition=" '$(NuGetPackageRoot)' == '' ">/home/js/.nuget/packages/</NuGetPackageRoot>
-    <NuGetPackageFolders Condition=" '$(NuGetPackageFolders)' == '' ">/home/js/.nuget/packages/</NuGetPackageFolders>
-    <NuGetProjectStyle Condition=" '$(NuGetProjectStyle)' == '' ">PackageReference</NuGetProjectStyle>
-    <NuGetToolVersion Condition=" '$(NuGetToolVersion)' == '' ">5.6.0</NuGetToolVersion>
-  </PropertyGroup>
-  <PropertyGroup>
-    <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
-  </PropertyGroup>
-</Project>

obj/BuecherwurmAPI.csproj.nuget.g.targets

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8" standalone="no"?>
-<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup>
-    <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
-  </PropertyGroup>
-</Project>

obj/project.assets.json

@@ -1,72 +0,0 @@
-{
-  "version": 3,
-  "targets": {
-    ".NETCoreApp,Version=v3.1": {}
-  },
-  "libraries": {},
-  "projectFileDependencyGroups": {
-    ".NETCoreApp,Version=v3.1": []
-  },
-  "packageFolders": {
-    "/home/js/.nuget/packages/": {}
-  },
-  "project": {
-    "version": "1.0.0",
-    "restore": {
-      "projectUniqueName": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj",
-      "projectName": "BuecherwurmAPI",
-      "projectPath": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj",
-      "packagesPath": "/home/js/.nuget/packages/",
-      "outputPath": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/obj/",
-      "projectStyle": "PackageReference",
-      "configFilePaths": [
-        "/home/js/.nuget/NuGet/NuGet.Config"
-      ],
-      "originalTargetFrameworks": [
-        "netcoreapp3.1"
-      ],
-      "sources": {
-        "https://api.nuget.org/v3/index.json": {}
-      },
-      "frameworks": {
-        "netcoreapp3.1": {
-          "projectReferences": {}
-        }
-      },
-      "warningProperties": {
-        "warnAsError": [
-          "NU1605"
-        ]
-      }
-    },
-    "frameworks": {
-      "netcoreapp3.1": {
-        "imports": [
-          "net461",
-          "net462",
-          "net47",
-          "net471",
-          "net472",
-          "net48"
-        ],
-        "assetTargetFallback": true,
-        "warn": true,
-        "downloadDependencies": [
-          {
-            "name": "Microsoft.AspNetCore.App.Ref",
-            "version": "[3.1.2, 3.1.2]"
-          }
-        ],
-        "frameworkReferences": {
-          "Microsoft.AspNetCore.App": {
-            "privateAssets": "none"
-          },
-          "Microsoft.NETCore.App": {
-            "privateAssets": "all"
-          }
-        },
-        "runtimeIdentifierGraphPath": "/usr/share/dotnet/sdk/3.1.300/RuntimeIdentifierGraph.json"
-      }
-    }
-  }
-}

obj/project.nuget.cache

@@ -1,10 +0,0 @@
-{
-  "version": 2,
-  "dgSpecHash": "DQHTkigAmzaLDZvres1QqICGpp078kH+e2RcIw20S2aZ61FIcBBy9GnDIw6JTzZ4/RxJvQ1+WRFn2orctypbfA==",
-  "success": true,
-  "projectFilePath": "/home/js/git/BuecherwurmAPI/BuecherwurmAPI/BuecherwurmAPI.csproj",
-  "expectedPackageFiles": [
-    "/home/js/.nuget/packages/microsoft.aspnetcore.app.ref/3.1.2/microsoft.aspnetcore.app.ref.3.1.2.nupkg.sha512"
-  ],
-  "logs": []
-}