Laravel error : Integrity constraint violation

ROUTE

             Route::post('/review','RentalController@review');
CONTROLLER

             public function review(Request $request)
           {
             $review = new Reviews();
            $rpId = rand();
            $review->rvid=$rpId;
            $review->usid_fk = Auth::user()->uid;
            // $propId= $request->input('propId');
            $review->prId_fk = $request->input('propId');;
            $review->comment = $request->input('comment');
            $review->rating = $request->input('rating');
            $review->date = Carbon::now();
            $review->save();


                 }
MIGRATE
              public function up()
        {
            Schema::create('review', function (Blueprint $table) {

                 $table->integer('rvId')->primary();
                   $table->integer('usId_fk');
                   $table->foreign('usId_fk')->references('uid')->on('users');
                   $table->integer('prId_fk');
                   $table->foreign('prId_fk')->references('pId')->on('properties');
                   $table->date('date');
                   $table->integer('rating');
                   $table->string('comment');
            });

        }
VIEW

             <form action="" method="POST">
             

          <div class="modal-body">
          <input type="hidden" name="propid" value=""/>
          <input id="rating" name="rating" class="rating rating-loading" data-show-clear="false" data-min="0" 
          data-max="5" data-step="1" value="0">


          <div class="input-group">
          <div class="input-group-prepend">
          <span class="input-group-text">Comment</span>
          </div>
          <textarea name="comment" class="form-control" aria-label="Comment"></textarea>

            </div>
          <div class="modal-footer">
            <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
            <button type="submit" class="btn btn-primary">Submit</button>
          </div>
          </form>

and the error is integrity contraintthe prId_fk cannot be null been trying to fix this a coule of days alreadyYour reply would be highly appreciatedthank you the prId_fk cannot be null integrity constraint violation

i've been trying to rerwite my code over and over again still it didnt work

via Chebli Mohamed