[Samples] Update Dependency Injection exercises

Author: florinc

LessonsSamples/LessonsSamples/Lesson6/DI-Demo/_Exercises.html

@@ -15,12 +15,18 @@ <h4 id="implement-the-console-options-as-a-set-of-commands-registered-into-di-co
     string MenuEntry { get; }
 }
 </code></pre>
-<p>Build the menu by getting all the <code>ICommand</code> implementations through constructor DI. When a menu entry is picked, it will execute that command by calling the <code>Execute()</code> function.</p>
+<p>Build the menu by getting all the <code>ICommand</code> implementations through constructor DI.
+When a menu entry is picked, it will execute that command by calling the <code>Execute()</code> function.
+The <code>MovieConsoleApplication</code> constructor can import all <code>IConsole</code> implementations as an <code>IEnumerable&lt;IConsole&gt;</code>:</p>
+<pre><code>    public MovieConsoleApplication(IEnumerable&lt;ICommand&gt; commands)
+    {
+    }
+</code></pre>
 <h4 id="create-an-abstraction-for-the-console-iconsole">2. Create an abstraction for the console: <code>IConsole</code></h4>
 <ol type="a">
-<li><p>Why would we abstract the existent static Console class through IConsole?</p>
+<li><p>Register in the DI Container the <code>IConsole</code> with the <code>AppConsole</code> implementation and refactor the code to use the <code>IConsole</code></p>
 </li>
-<li><p>Register in the DIC the <code>IConsole</code> with the <code>AppConsoleImplementation</code> and refactor the code to use the <code>IConsole</code></p>
+<li><p>What benefits can you see?</p>
 </li>
 </ol>
 <h4 id="integrate-the-servicelocator-into-the-app">3. Integrate the <code>ServiceLocator</code> into the app</h4>
@@ -34,34 +40,60 @@ <h4 id="rewrite-the-moviesconsolecreator">5. Rewrite the <code>MoviesConsoleCrea
 <li>Reimplement the <code>MoviesConsoleCreator</code> command to support the following functionality:</li>
 </ol>
 <ul>
-<li>read more properties of a movie one by one. They UI will present the user the name of the property that she should enter</li>
-<li>The Movie should have at least the following fields: <code>Title :string</code> and <code>Rating :int</code></li>
+<li>read more properties of a movie one by one. They UI will show to the user the name of the property that she should enter</li>
+<li>The Movie should have at least the following fields: <code>Title :string</code> and <code>Rating :int</code> (see <code>Movie.cs</code>)</li>
 <li>when all properties of a movie were read, ask the user if she wants to add a new movie</li>
 </ul>
 <p>Use the following interfaces:</p>
 <pre><code>interface IEntityReader
 {
-    IEntityFieldsReader&lt;T&gt; BeginEntityRead&lt;T&gt;();
+    IEntityFieldsReader&lt;TEntity&gt; BeginEntityRead&lt;TEntity&gt;();
 }
 
-interface IEntityFieldsReader&lt;T&gt;
+interface IEntityFieldsReader&lt;TEntity&gt;
 {
     IEnumerable&lt;string&gt; GetFields();
     void SetFieldValue(string value);
-    T GetEntity();
+    TEntity GetEntity();
 }
 
-interface IEntityRepository
+interface IEntityRepository&lt;TEntity&gt;
 {
-    IEnumerable&lt;Movie&gt; GetAll();
-    void Add(Movie movie);
+    IEnumerable&lt;TEntity&gt; GetAll();
+    void Add(TEntity movie);
 }
 </code></pre>
 <ol type="a" start="2">
 <li>Write unit tests that prove that the new <code>MoviesConsoleCreator</code> works</li>
 </ol>
 <h4 id="implement-ientityreader-and-ientityfieldsreader">6. Implement <code>IEntityReader</code> and <code>IEntityFieldsReader</code></h4>
-<p><em>Suggestion</em>: Use <em>Service Locator Pattern</em> to get and return the <code>IEntityFieldsReader&lt;T&gt;</code> implementations on the <code>IEntityReader&lt;T&gt;()</code> function.</p>
+<pre><code>class EntityReader : IEntityReader
+{
+    public IEntityFieldsReader&lt;TEntity&gt; BeginEntityRead&lt;TEntity&gt;()
+    {
+        ...
+    }
+}
+
+class MovieFieldsReader : IEntityFieldsReader&lt;Movie&gt;
+{
+    public IEnumerable&lt;string&gt; GetFields()
+    {
+        ...
+    }
+    
+    public void StoreFieldValue(string name, string value)
+    {
+        ...
+    }
+
+    public Movie GetEntity()
+    {
+        ...
+    }
+}
+</code></pre>
+<p><em>Suggestion</em>: Use <em>Service Locator Pattern</em> to get and return the <code>IEntityFieldsReader&lt;TEntity&gt;</code> implementations on the <code>IEntityReader&lt;TEntity&gt;()</code> function.</p>
 <h4 id="make-a-generic-implementation-of-ientityfieldsreadert">7. Make a generic implementation of  <code>IEntityFieldsReader&lt;T&gt;</code></h4>
 <p>We may have a generic class that implements <code>IEntityFieldsReader&lt;T&gt;</code> for any T by using reflection. It should be registered to DI by using the open generic type.</p>
 <h4 id="implement-option-4.find-movies">8. Implement option <em>4. Find Movies</em></h4>

LessonsSamples/LessonsSamples/Lesson6/DI-Demo/_Exercises.md

@@ -12,13 +12,21 @@ public interface ICommand
 }
 ```
 
-Build the menu by getting all the `ICommand` implementations through constructor DI. When a menu entry is picked, it will execute that command by calling the `Execute()` function.
+Build the menu by getting all the `ICommand` implementations through constructor DI. 
+When a menu entry is picked, it will execute that command by calling the `Execute()` function.
+ The `MovieConsoleApplication` constructor can import all `IConsole` implementations as an `IEnumerable<IConsole>`:
+
+```
+    public MovieConsoleApplication(IEnumerable<ICommand> commands)
+    {
+    }
+```
 
 #### 2. Create an abstraction for the console: `IConsole`
 
-a) Why would we abstract the existent static Console class through IConsole? 
+a) Register in the DI Container the `IConsole` with the `AppConsole` implementation and refactor the code to use the `IConsole`
 
-b) Register in the DIC the `IConsole` with the `AppConsoleImplementation` and refactor the code to use the `IConsole`
+b) What benefits can you see?
 
 #### 3. Integrate the `ServiceLocator` into the app
 
@@ -30,29 +38,29 @@ b) Register in the DIC the `IConsole` with the `AppConsoleImplementation` and re
 #### 5. Rewrite the `MoviesConsoleCreator`
 
 a) Reimplement the `MoviesConsoleCreator` command to support the following functionality:
- - read more properties of a movie one by one. They UI will present the user the name of the property that she should enter
- - The Movie should have at least the following fields: `Title :string` and `Rating :int`
+ - read more properties of a movie one by one. They UI will show to the user the name of the property that she should enter
+ - The Movie should have at least the following fields: `Title :string` and `Rating :int` (see `Movie.cs`)
  - when all properties of a movie were read, ask the user if she wants to add a new movie
 
 Use the following interfaces:
 
 ```
 interface IEntityReader
 {
-    IEntityFieldsReader<T> BeginEntityRead<T>();
+    IEntityFieldsReader<TEntity> BeginEntityRead<TEntity>();
 }
 
-interface IEntityFieldsReader<T>
+interface IEntityFieldsReader<TEntity>
 {
     IEnumerable<string> GetFields();
     void SetFieldValue(string value);
-    T GetEntity();
+    TEntity GetEntity();
 }
 
-interface IEntityRepository
+interface IEntityRepository<TEntity>
 {
-    IEnumerable<Movie> GetAll();
-    void Add(Movie movie);
+    IEnumerable<TEntity> GetAll();
+    void Add(TEntity movie);
 }
 ```
 
@@ -61,7 +69,35 @@ b) Write unit tests that prove that the new `MoviesConsoleCreator` works
 
 #### 6. Implement `IEntityReader` and `IEntityFieldsReader`
 
-*Suggestion*: Use *Service Locator Pattern* to get and return the `IEntityFieldsReader<T>` implementations on the `IEntityReader<T>()` function.
+```
+class EntityReader : IEntityReader
+{
+    public IEntityFieldsReader<TEntity> BeginEntityRead<TEntity>()
+    {
+        ...
+    }
+}
+
+class MovieFieldsReader : IEntityFieldsReader<Movie>
+{
+    public IEnumerable<string> GetFields()
+    {
+        ...
+    }
+    
+    public void StoreFieldValue(string name, string value)
+    {
+        ...
+    }
+
+    public Movie GetEntity()
+    {
+        ...
+    }
+}
+```
+
+*Suggestion*: Use *Service Locator Pattern* to get and return the `IEntityFieldsReader<TEntity>` implementations on the `IEntityReader<TEntity>()` function.
 
 #### 7. Make a generic implementation of  `IEntityFieldsReader<T>`