Unable to process POST request for create action in controller - ruby-on-rails

Question

I am using paperclip-5.0.0, and Rails 5.0.2.This is my code in controller
class PawsController < ApplicationController
before_action :set_paw, only: [:show, :edit]
def index
#paws = Paw.all
end
def show
end
def new
#paw = Paw.new
end
def edit
end
def create
#paw = Paw.new(paw_params)
respond_to do |format|
if #paw.save
format.html { redirect_to #paw, notice: 'Paw was successfully created.' }
format.json { render :show, status: :created, location: #paw }
else
format.html { render :new }
format.json { render json: #paw.errors, status: :unprocessable_entity }
end
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_paw
#paw = Paw.find(params[:id])
end
def paw_params
params.require(:paw).permit(:avatar,:name) if params[:avatar]
end
end
Avatar here is the column for paw which stores images.In model I have added required validations for paperclip and validation for presence of name.
Problem: In rails console I am successfully able to open the image file from my computer and add it to the paw model i.e. #paw.save returns true in console, but in the browser it redirects me to the new_paw_url with two errors.
Name can't be blank. and
Avatar can't be blank.
There are no exceptions or errors thrown in between the process.I have no idea how should I fix this.
ActiveRecord::SchemaMigration Load (0.2ms) SELECT "schema_migrations".* FROM "schema_migrations"
Processing by PawsController#create as HTML
Parameters: {"utf8"=>"✓","authenticity_token"=>"zKpb2XFEG4FqX3aVQx9oyyGI9x2NpmF+lmt4eZy/3p3VZr2eWYvHLaEjS5AvisJ6iEbRm61SJkJSuTpMx4c0JA==", "paw"=>{"name"=>"Sheru", "gender"=>"Male", "breed"=>"", "dob"=>"", "avatar"=>#<ActionDispatch::Http::UploadedFile:0x005608576e1f30 #tempfile=#<Tempfile:/tmp/RackMultipart20170323-14343-1o95nqx.jpg>, #original_filename="art.jpg", #content_type="image/jpeg", #headers="Content-Disposition: form-data; name=\"paw[avatar]\"; filename=\"art.jpg\"\r\nContent-Type: image/jpeg\r\n">}, "commit"=>"Upload"}
(0.1ms) begin transaction
(0.1ms) rollback transaction
(0.1ms) begin transaction
(0.1ms) rollback transaction
Rendering paws/new.html.erb within layouts/application
Rendered paws/_form.html.erb (15.8ms)
Rendered paws/new.html.erb within layouts/application (17.3ms)
Rendered layouts/_navbar.html.erb (0.6ms)
Completed 200 OK in 326ms (Views: 287.5ms | ActiveRecord: 2.0ms)
Feel free to ask for any other code snippets from me.

Answer 1

Your paw_params method is breaking it. Remove the if statement and it should work. The problem you're having is that the params you're recieving through your controller are nested in the params[paw] hash and not the params hash. Your paw_params if statement should be
params.require(:paw).permit(:avatar,:name) if params[:paw][:avatar]
Look at the console of your params hash and you'll see that Rails will nest all params submitted via a form helper within the class name of the object. In this case it's paw.
"paw"=>{"name"=>"Sheru", "gender"=>"Male", "breed"=>"", "dob"=>"", "avatar"=>#<ActionDispatch::Http::UploadedFile:0x005608576e1f30
More obviously:
params[:name] #nil
params[:paw][:name] #"Sheru"
Also, it's not a good practice to add conditionals for strong_paramaters based on the presence of certain attributes. If someone submits a name without an avatar, the name wont be permitted due to strong_parameters but would give the user poor feedback. Instead you should use validations in your Paw model that requires the presence of both the name and avatar.