code to get controller render errors when required param is missing

app/controllers/schemes_controller.rb

@@ -30,8 +30,12 @@ class SchemesController < ApplicationController
   end
 
   def create
-    @scheme = Scheme.create!(scheme_params)
+    @scheme = Scheme.new(scheme_params)
+    if @scheme.save
       render "schemes/primary_client_group"
+    else
+      render :new, status: :unprocessable_entity
+    end
   end
 
   def update

app/models/scheme.rb

@@ -5,6 +5,8 @@ class Scheme < ApplicationRecord
   has_many :locations
   has_many :case_logs
 
+  validates :organisation_id, presence: { message: I18n.t("validations.scheme.id_missing") }
+
   scope :search_by_code, ->(code) { where("code ILIKE ?", "%#{code}%") }
   scope :search_by_service_name, ->(name) { where("service_name ILIKE ?", "%#{name}%") }
   scope :search_by_postcode, ->(postcode) { joins(:locations).where("locations.postcode ILIKE ?", "%#{postcode.delete(' ')}%") }

config/locales/en.yml

@@ -39,6 +39,9 @@ en:
     reset_password: "Reset your password"
 
   validations:
+    scheme:
+      id_missing: "Enter the organisation’s name"
+
     organisation:
       name_missing: "Enter the organisation’s name"
       provider_type_missing: "Select the organisation’s type"