PG::ForeignKeyViolation: ERROR: update or delete on table and I don't know why in my case

Question

I am contacting you because I have a rather important problem. And that despite my research on stackoverflow or elsewhere, I can not correct after a lot of testing and a lot of tinkering.

I practice by making a site where you can list secrets that I call "gossip".

There is a button that allows you to delete a "gossip".

But when I want to remove the "gossip"

I have an error message which is the following :

From what I understand, it is my relationship between the tables that is causing the problem. I therefore attach you my code of these tables in questions :

class Tag < ApplicationRecord
  has_many :gossips, through: :tag_join_gossip, dependent: :destroy

  validates :title, presence: true
end

class TagJoinGossip < ApplicationRecord
  belongs_to :gossip
  belongs_to :tag, optional: true
end

class Gossip < ApplicationRecord
  belongs_to :user, optional: true
  has_many :likes
  has_many :tags, through: :tag_join_gossip
  has_many :comments

  validates :title, presence: true, length: {minimum: 3, maximum: 14}
  validates :content, presence: true, length: {minimum: 1}

end

My controller :

class GossipController < ApplicationController
  before_action :authenticate_user
  def index
    @id = params[:id]
    @gossips = Gossip.all
    
  end 
  
 

  def show
    @id= params[:id]
    @gossip = Gossip.find(params[:id])
    @comments = Gossip.find(params[:id]).comments
    @comment = Comment.new(content: params['content'], gossip_id: 1, gossip_id: @gossip ,user_id: 1)
  end
 
 
    def new
     @gossip = Gossip.new
     
    end
    
    def create
      
      @gossip = Gossip.new(title: params['title'], content: params['content'])
      @gossip.user = User.find_by(id: session[:user_id])

      if @gossip.save
        flash[:success] = "Gossip bien créé!"
        redirect_to welcome_index_path

      else
        flash[:danger] = "Nous n'avons pas réussi à créer le potin pour la (ou les) raison(s) suivante(s) "
        render new_gossip_path
      end
 end

    

  
    def edit
      @gossip = Gossip.find(params[:id])
    end
  
    def update
      @gossip = Gossip.find(params[:id])

      gossip_params = params.require(:gossip).permit(:title, :content)

      if @gossip.update(gossip_params)
        flash[:success] = "Gossip bien modifié !"
         redirect_to welcome_index_path
      else
        render :edit   
        flash[:danger] = "Nous n'avons pas réussi à modifier le potin, le titre doit faire 3 lettres minimum et vous devez remplir le contenu."
    end
  end
  
    def destroy
      
      @gossip = Gossip.find(params[:id])
      @gossip.destroy
      redirect_to welcome_index_path
    end
  end

  private

  def authenticate_user
    unless current_user
      flash[:danger] = "Veuillez vous connecter."
      redirect_to new_session_path
    end
  end

Maybe there are other files that can be of interest so I put my project's github here : https://github.com/MC4517/Projet-THP-GOSSIP-J1

I've been on it all day, I'm starting to lose my mind lol.

Thank you very much for those who venture into my problem, although I think it must be easy for a large part of you!

Answer 1

You have a record with a foreign key (TagJoinGossip) referencing the record you want to destroy (Gossip). Adding dependent: :destroy to the has_many association should solve it.

 Class Gossip < ApplicationRecord
 
     has_many :tags, through: :tag_join_gossip, dependent: :destroy