title: nothing happens when i submit a form in MEAN STACK
body: <p>so the project is so simple. the user inputs some infos about a book and click submit to save the infos in a database (Mongodb) i'm using MEAN STACK and i'm a noobie (obviously). nothing happens when i submit not even an error.</p>
  <p><strong>backend code :</strong></p>
  <pre><code>    //POST ONE BOOK
      booksRoute.route('/post').post((req,res,next)=&gt;{
          var x = {
              name   : req.params.name,
              genre  : req.params.genre,   
              author : req.params.author,
              rating : req.params.rating,
              price  : req.params.price
          }
          console.log(x) ; 
          BookModel(x).save((err,data)=&gt;{
              if (err){console.log(err);}
              else res.send(data) ;
  }) ;
  })
  </code></pre>
  <p><strong>add book component html :</strong></p>
  <pre><code>&lt;ul&gt;
      &lt;form #f=&quot;ngForm&quot; (ngSubmit)=&quot;onSubmit(f)&quot;&gt;  
      &lt;li&gt;
      &lt;label&gt;book's name *&lt;/label&gt;
      &lt;input name=&quot;name&quot; type=&quot;text&quot; ngModel&gt;
      &lt;/li&gt;
      &lt;li&gt;
      &lt;label&gt;book's genre *&lt;/label&gt;
      &lt;input name=&quot;genre&quot; type=&quot;text&quot; ngModel&gt;
      &lt;/li&gt;
      &lt;li&gt;
      &lt;label&gt;book's author *&lt;/label&gt;
      &lt;input name=&quot;author&quot; type=&quot;text&quot; ngModel&gt;
      &lt;/li&gt;
      &lt;li&gt;
      &lt;label&gt;rating *&lt;/label&gt;
      &lt;input name=&quot;rating&quot; type=&quot;number&quot; [max]=&quot;10&quot; min=&quot;0&quot; ngModel&gt;
      &lt;/li&gt;
      &lt;li&gt;
      &lt;label&gt;price *&lt;/label&gt;
      &lt;input name=&quot;price&quot; type=&quot;number&quot; ngModel&gt;
      &lt;input class=&quot;btn btn-primary&quot; type=&quot;submit&quot;/&gt; 
      &lt;/li&gt;  
  &lt;/form&gt;
  &lt;/ul&gt;
  </code></pre>
  <p><strong>angular service</strong></p>
  <pre><code>  postBook(data){
      console.log(data) ;
      return this.http.post(this.backendUrl+'/post',data) ;
    }
  </code></pre>
  <p><strong>in addBook component ts</strong></p>
  <pre><code>onSubmit(f){
      //console.log(f.value) ;
      this.apiService.postBook(f.value) ; 
    }
  </code></pre>
  <p><strong>Note</strong> : i can get data from the database, i can find a book by it's name but i can't post</p>