Android Room: Insert relation entities using Room

Question

I\'ve added one to many relationship in Room using Relation. I referred to this post to write the following code for relation in Room.

The post tells how to read th

Answer 1

I managed to insert it properly with a relatively simple workaround. Here are my entities:

   @Entity
public class Recipe {
    @PrimaryKey(autoGenerate = true)
    public long id;
    public String name;
    public String description;
    public String imageUrl;
    public int addedOn;
   }


  @Entity
public class Ingredient {
   @PrimaryKey(autoGenerate = true)
   public long id;
   public long recipeId; 
   public String name;
   public String quantity;
  }

public class RecipeWithIngredients {
   @Embedded
   public  Recipe recipe;
   @Relation(parentColumn = "id",entityColumn = "recipeId",entity = Ingredient.class)
   public List ingredients;

I am using autoGenerate for auto-increment value(long is used with a purpoes). Here is my solution:

  @Dao
public abstract class RecipeDao {

  public  void insert(RecipeWithIngredients recipeWithIngredients){
    long id=insertRecipe(recipeWithIngredients.getRecipe());
    recipeWithIngredients.getIngredients().forEach(i->i.setRecipeId(id));
    insertAll(recipeWithIngredients.getIngredients());
  }

public void delete(RecipeWithIngredients recipeWithIngredients){
    delete(recipeWithIngredients.getRecipe(),recipeWithIngredients.getIngredients());
  }

 @Insert
 abstract  void insertAll(List ingredients);
 @Insert
 abstract long insertRecipe(Recipe recipe); //return type is the key here.

 @Transaction
 @Delete
 abstract void delete(Recipe recipe,List ingredients);

 @Transaction
 @Query("SELECT * FROM Recipe")
 public abstract List loadAll();
 }

I had problem linking the entities, auto generate produced "recipeId=0" all the time. Inserting the recipe entity firstly fixed it for me.