rails uniqueness

# Step 1: Add a unique constraint to the database column
class AddUniqueConstraintToTableName < ActiveRecord::Migration[6.0]
  def change
    add_index :table_name, :column_name, unique: true
  end
end

# Step 2: Validate uniqueness in the model
class ModelName < ApplicationRecord
  validates :attribute_name, uniqueness: true
end

# Step 3: Handle validation errors in the controller
class ControllerName < ApplicationController
  def create
    @model_instance = ModelName.new(model_params)
    if @model_instance.save
      # Successful save
    else
      # Handle uniqueness validation error
    end
  end

  private

  def model_params
    # Permit the required parameters
    params.require(:model_name).permit(:attribute_name)
  end
end