ActiveRecord::NotNullViolation in InscriptionsController#create

I just want to check my registrations form in rails 7 in Ubuntu 22, but it is not working as it should, and I'm still getting some error. The app should send with the POST request data to the server after filling the registrations form in.

I have to fill the registrations form to test it, but I get the following error message:

Started POST "/inscriptions" for 127.0.0.1 at 2023-06-18 15:44:51 +0200
Processing by InscriptionsController#create as TURBO_STREAM
Parameters: {"authenticity_token"=>"[FILTERED]", "inscription"=>{"vorname"=>"Jade", "name"=>"Doe", "age"=>"13", "adress"=>"3 Marguerite Youcenar", "email"=>"jade_doe@gmail.com", "phone"=>"0768324654", "gender"=>"feminin"}, "commit"=>"Envoyer"}
TRANSACTION (0.5ms)  BEGIN
↳ app/controllers/inscriptions_controller.rb:27:in `block in create'
Inscription Create (11.6ms)  INSERT INTO "inscriptions" ("vorname", "name", "age", "adress", "email", "phone", "gender", "created_at", "updated_at", "club_id") VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10) RETURNING "id"  [["vorname", "Jade"], ["name", "Doe"], ["age", "13"], ["adress", "3 Marguerite Youcenar"], ["email", "jade_doe@gmail.com"], ["phone", "0768324654"], ["gender", "feminin"], ["created_at", "2023-06-18 13:44:51.944100"], ["updated_at", "2023-06-18 13:44:51.944100"], ["club_id", nil]]
↳ app/controllers/inscriptions_controller.rb:27:in `block in create'
TRANSACTION (0.9ms)  ROLLBACK
↳ app/controllers/inscriptions_controller.rb:27:in `block in create'
Completed 500 Internal Server Error in 30ms (ActiveRecord: 13.0ms | Allocations: 5257)
ActiveRecord::NotNullViolation (PG::NotNullViolation: ERREUR:  une valeur NULL viole la contrainte NOT NULL de la colonne « club_id » dans la relation « inscriptions »
DETAIL:  La ligne en échec contient (15, Jade, Doe, 13, 3 Marguerite Youcenar, jade_doe@gmail.com, 0768324654, feminin, 2023-06-18 13:44:51.9441, 2023-06-18 13:44:51.9441, null).
):

The following image shows some of my code I use for this app
The inscription controller:

class InscriptionsController < ApplicationController
before_action :set_inscription, only: %i[ show edit update destroy ]
# GET /inscriptions or /inscriptions.json
def index
@inscriptions = Inscription.all
end
# GET /inscriptions/1 or /inscriptions/1.json
def show
end
# GET /inscriptions/new
def new
@inscription = Inscription.new
end
# GET /inscriptions/1/edit
def edit
end
# POST /inscriptions or /inscriptions.json
def create
@inscription = Inscription.new(inscription_params)
respond_to do |format|
if @inscription.save
format.html { redirect_to inscription_url(@inscription), notice: "Inscription was successfully created." }
format.json { render :show, status: :created, location: @inscription }
else
format.html { render :new, status: :unprocessable_entity }
format.json { render json: @inscription.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /inscriptions/1 or /inscriptions/1.json
def update
respond_to do |format|
if @inscription.update(inscription_params)
format.html { redirect_to inscription_url(@inscription), notice: "Inscription was successfully updated." }
format.json { render :show, status: :ok, location: @inscription }
else
format.html { render :edit, status: :unprocessable_entity }
format.json { render json: @inscription.errors, status: :unprocessable_entity }
end
end
end
# DELETE /inscriptions/1 or /inscriptions/1.json
def destroy
@inscription.destroy
respond_to do |format|
format.html { redirect_to inscriptions_url, notice: "Inscription was successfully destroyed." }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_inscription
@inscription = Inscription.find(params[:id])
end
# Only allow a list of trusted parameters through.
def inscription_params
params.require(:inscription).permit(:club_name, :age, :vorname, :name, :adress, :email, :phone, :gender)
end
end

The model look like this:

class Inscription < ApplicationRecord
belongs_to :club, :optional => true
#validates :club_name, presence: true
validates :name, presence: true
validates :age, presence: true, numericality: { only_integer: true, greater_than: 0 }
validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }
validates :phone, presence: true , format: { with: /\A\d{10}\z/ }
end

The club model:

class Club < ApplicationRecord
belongs_to :ClubAdulte
belongs_to :ClubTeevo
belongs_to :ClubJeuneLecteur
end

It means you have NOT NULL constraint

Since you have belongs_to association with optional: true option, you need fix database layer by adding and executing new migration

def change
change_column_null :inscriptions, :club_id, null: true
end