Add a field in a many-to-one relation in NestJS - mysql

Question

I am trying to develop a small application to record cooking recipes. To do this, I declared 2 entities with nestJS allowing me to manage the recipes and another to manage the ingredients. I also created a 3rd entity to record the quantities of ingredients needed :
Database diagram
// recipe.entity.js
#Entity()
export class Recipe {
#PrimaryGeneratedColumn()
id: number
#Column('datetime')
createdAt: Date
#Column('datetime')
updatedAt: Date
#Column('varchar', { length: 100 })
title: string;
#Column('varchar', {nullable: true})
image: string;
#OneToMany(type => RecipeIngredients, recipeIngredients => recipeIngredients.recipe)
ingredients: RecipeIngredients[];
}
// ingredient.entity.js
#Entity()
export class Ingredient {
#PrimaryGeneratedColumn()
id: number
#Column('datetime')
createdAt: Date
#Column('datetime')
updatedAt: Date
#Column('varchar', { length: 100 })
name: string;
#Column('varchar', {nullable: true})
image: string;
#OneToMany(type => RecipeIngredients, recipeIngredients => recipeIngredients.ingredient)
recipes: RecipeIngredients[];
}
// recipe_ingredients.entity.js
#Entity()
export class RecipeIngredients {
#PrimaryGeneratedColumn()
id: number
#ManyToOne(type => Recipe, recipe => recipe.ingredients)
recipe: Recipe
#ManyToOne(type => Ingredient)
ingredient: Ingredient
#Column()
quantity: string;
}
First, I would like to be able to retrieve a recipe with the list of necessary ingredients:
const recipe = await this.recipesRepository.createQueryBuilder('recipe')
.where('recipe.id = :recipeId', {recipeId: _id})
.leftJoin('recipe.ingredients', 'recipe_ingredients')
.leftJoin('recipe_ingredients.ingredient', 'ingredient')
.getMany();
But this method returns only my recipe object without the ingredients...
[
{
"id": 1,
"createdAt": "2020-04-30T09:12:22.000Z",
"updatedAt": "2020-04-30T09:12:22.000Z",
"title": "Test",
"image": null
}
]
From there, I'm lost ... How can I get the list of my ingredients (at least the name and quantity fields) directly from my service?
Thank you in advance for your help.

Answer 1

Using leftJoin will able you to join data without its selection. It selects the recipe if it has ingredients, but won't return its ingredients.
As read in TypeORM's documentation :
You can join data without its selection. To do that, use leftJoin or
innerJoin:
const user = await createQueryBuilder("user")
.innerJoin("user.photos", "photo")
.where("user.name = :name", { name: "Timber" })
.getOne();
This will generate:
SELECT user.* FROM users user
INNER JOIN photos photo ON photo.user = user.id
WHERE user.name = 'Timber'
This will select Timber if he has photos, but won't return his photos.
To select the ingredients try using leftJoinAndSelect instead.