title: Android Room On delete Cascade doesn't work
body: <p>I know there are a lot of posts about this kind of subject but they all deal with SQLite... (mine is about Room). </p>
  
  <p>I have a one-to-many relation between a "Card" table and a "Deck" table. So a card has 1 Deck and a Deck has Many cards. Insertion and Deletion are OK for 1 row but i'd like to delete the cards of a deck when this one is removed : on Delete cascade relationship. </p>
  
  <p>My code :</p>
  
  <p>(Card.class) </p>
  
  <pre><code>@Entity(tableName = "cards")
  public class Card{
  
      @PrimaryKey(autoGenerate = true)
      @ColumnInfo(name = "id")
      public int id;
  
      @ColumnInfo(name = "face1")
      public String face1;
  
      @ColumnInfo(name = "face2")
      public String face2;
  
      @ColumnInfo(name = "id_deck")
      @ForeignKey(entity = Deck.class, parentColumns = "id", childColumns = 
      "id_deck", onDelete = CASCADE)
      public int id_deck;
  }
  </code></pre>
  
  <p>Deck.class : </p>
  
  <pre><code>@Entity(tableName = "decks")
  public class Deck {
  
      @PrimaryKey(autoGenerate = true)
      @ColumnInfo(name = "id")
      public int id;
  
      @ColumnInfo(name = "nom")
      public String nom;
  
      public Deck(String nom){
          this.nom = nom;
      }
  
  }
  </code></pre>
  
  <p>Did i make something wrong ? When I remove a Deck, the cards still exist.</p>