add user follow feature

app/controllers/user_follows_controller.rb

@@ -0,0 +1,53 @@
+class UserFollowsController < ApplicationController
+  before_action :set_user_follow, only: %i[ show update destroy ]
+
+  # GET /user_follows
+  # GET /user_follows.json
+  def index
+    @user_follows = UserFollow.all
+  end
+
+  # GET /user_follows/1
+  # GET /user_follows/1.json
+  def show
+  end
+
+  # POST /user_follows
+  # POST /user_follows.json
+  def create
+    @user_follow = UserFollow.new(user_follow_params)
+
+    if @user_follow.save
+      render :show, status: :created, location: @user_follow
+    else
+      render json: @user_follow.errors, status: :unprocessable_entity
+    end
+  end
+
+  # PATCH/PUT /user_follows/1
+  # PATCH/PUT /user_follows/1.json
+  def update
+    if @user_follow.update(user_follow_params)
+      render :show, status: :ok, location: @user_follow
+    else
+      render json: @user_follow.errors, status: :unprocessable_entity
+    end
+  end
+
+  # DELETE /user_follows/1
+  # DELETE /user_follows/1.json
+  def destroy
+    @user_follow.destroy
+  end
+
+  private
+    # Use callbacks to share common setup or constraints between actions.
+    def set_user_follow
+      @user_follow = UserFollow.find(params[:id])
+    end
+
+    # Only allow a list of trusted parameters through.
+    def user_follow_params
+      params.require(:user_follow).permit(:follower_id, :followed_id)
+    end
+end