ManyToMany : Cannot add or update a child row: a foreign key constraint fails

[LeadcodeDev]

Hi! During my development I encountered a problem concerning the update only of a model having a ManyToMany relation (see attachment).

Here is the error and my data doesn't update, do you know why ?

[1599767787944] ERROR (api/15444 on DESKTOP-9Q3Q14G): insert into `achievements_technology` (`achievements_id`, `technology_id`) values (1, '[object Object]') - ER_NO_REFERENCED_ROW_2: Cannot add or update a child row: a foreign key constraint fails (`portfolio-adonis-nuxt`.`achievements_technology`, CONSTRAINT `achievements_technology_technology_id_foreign` FOREIGN KEY (`technology_id`) REFERENCES `technologies` (`id`))

My models :

// Achievement model
export default class Achievements extends BaseModel {
	@column({ isPrimary: true })
	public id: number

	@column()
	public title: string

	@column()
	public description: string

	@column()
	public url: string

	@column()
	public pictureId: number

	@manyToMany(() => Technology)
	public technologies: ManyToMany<typeof Technology>
}

// Technologies model
export default class Technology extends BaseModel {
	@column({ isPrimary: true })
	public id: number

	@column()
	public label: string

	@column()
	public description: string

	@column()
	public url: string

	@column()
	public pictureId: number
}

My pivot table

public async up() {
    this.schema.createTable(this.tableName, (table) => {
        table.increments('id')
	table.integer('technology_id').unsigned().references('id').inTable('technologies')
	table.integer('achievements_id').unsigned().references('id').inTable('achievements')
    })
}

My controller :

public async update({ request, params }: HttpContextContract) {
	const technologies = await request.input('technologies')
	const achievement = await Achievement.findOrFail(params.id)
	const data = await request.validate({
		schema: schema.create({
			title: schema.string(),
			description: schema.string(),
			url: schema.string(),
			picture_id: schema.number()
		})
	})
	await achievement.merge(data).related('technologies').sync(technologies)

	return { message: 'La ressource a été mis à jour' }
}

EDIT: my data (title, description, url) is now saved but my error above is still present

[RomainLanz]

Hey @LeadcodeDev! 👋

If you have a closer look to the error, you can see that you are not sending a correct parameter when calling sync().

insert into `achievements_technology` (`achievements_id`, `technology_id`) values (1, '[object Object]')

You must troubleshoot what you have inside technologies.

[LeadcodeDev]

I actually passed an array in the sync () function (as indicated in the documentation) but it was not made up of numbers but of objects... the error actually comes from there..

The solution (for other people who have this problem is to check that only the ids are present in the array)

Thanks again @RomainLanz