title: Gorm returns just one instead of multiple results
body: <p>I wrote blow codes and it returns just 1 row instead of 4:</p>
  
  <pre class="lang-golang prettyprint-override"><code>package main
  
  import (
      "fmt"
  
      "github.com/jinzhu/gorm"
      _ "github.com/jinzhu/gorm/dialects/sqlite"
  )
  
  type Post struct {
      gorm.Model
      Title    string
      Text     string
      Comments []Comment
  }
  
  type Comment struct {
      gorm.Model
      Text   string
      PostID uint `gorm:"foreignkey:ID;association_foreignkey:PostID"`
  }
  
  func main() {
      db, err := gorm.Open("sqlite3", "test.db")
      if err != nil {
          panic("failed to connect to database")
      }
      defer db.Close()
  
      db.DropTableIfExists(&amp;Post{}, &amp;Comment{})
      db.AutoMigrate(&amp;Post{}, &amp;Comment{})
  
      // fill db
      db.Create(&amp;Post{Title: "test1 title", Text: "text1"})
      db.Create(&amp;Post{Title: "test2 title", Text: "text2"})
      db.Create(&amp;Post{Title: "test3 title", Text: "text3"})
      db.Create(&amp;Comment{Text: "test1 comment1", PostID: 3})
      db.Create(&amp;Comment{Text: "test2 comment1", PostID: 2})
      db.Create(&amp;Comment{Text: "test3 comment2", PostID: 2})
      db.Create(&amp;Comment{Text: "test4 comment3", PostID: 2})
      db.Create(&amp;Comment{Text: "test5 comment4", PostID: 2})
      db.Create(&amp;Comment{Text: "test6 comment1", PostID: 1})
      //end fill db
  
      var myPost Post
      var comments Comment
      db.First(&amp;myPost, 2)
      db.Model(&amp;myPost).Related(&amp;comments)
  
      fmt.Println(myPost)
      fmt.Println(comments)
  }
  </code></pre>
  
  <p>and this is my output: </p>
  
  <pre><code>{{2 2019-04-08 17:04:20.3781288 +0430 +0430 2019-04-08 17:04:20.3781288 +0430 +0430 &lt;nil&gt;} test2 title text2 []}
  {{5 2019-04-08 17:04:20.4091133 +0430 +0430 2019-04-08 17:04:20.4091133 +0430 +0430 &lt;nil&gt;} test5 comment4 2}
  </code></pre>
  
  <p>you can see just one row: </p>
  
  <pre><code>test5 comment4 
  </code></pre>
  
  <p>and I expect this result:</p>
  
  <pre><code>test2 comment1
  test3 comment2
  test4 comment3
  test5 comment4
  </code></pre>
  
  <p>What should I do to get 4 rows result?</p>
  
  <p>I already read all the documentation of gorm. and this example of doc is not working for me as I expect
  <a href="http://doc.gorm.io/associations.html#has-many" rel="nofollow noreferrer">http://doc.gorm.io/associations.html#has-many</a></p>
  
  <pre><code>Has Many
  // User has many emails, UserID is the foreign key
  type User struct {
      gorm.Model
      Emails   []Email
  }
  
  type Email struct {
      gorm.Model
      Email   string
      UserID  uint
  }
  
  db.Model(&amp;user).Related(&amp;emails)
  //// SELECT * FROM emails WHERE user_id = 111; // 111 is user's primary key
  </code></pre>