ruby on rails - Prepopulating form with data after API sends error in JSON -

i have frontend rails app requesting rails api. when user wants create account, submitting account form on front-end app :

<h1>create account</h1> <form action="http://localhost:3000/accounts" method="post">   <input name="authenticity_token" value="<%= form_authenticity_token %>" type="hidden">   <div class="form-group">     <%= label_tag 'account[name]', "name" %>     <input type="text" name="account[name]" required>   </div>   <div class="form-group">     <%= label_tag "account[contact_mail]", "e-mail" %>     <input type="text" name= "account[contact_mail]" required>   </div>   <div class="form-group">     <%= label_tag "account[contact_tel]", "telephone" %>     <input type="text" name= "account[contact_tel]" required>   </div>   <div class="form-group">     <%= label_tag "account[iban]", "iban" %>     <input type="text" name= "account[iban]">   </div>   <div class="form-group">     <%= label_tag "account[bic]", "bic" %>     <input type="text" name= "account[bic]">   </div>   <input type="submit">     <% if @errors %>     <ul class="list-unstyled">       <%@errors.each |error|%>         <li class="has-error"><%=error%></li>       <% end -%>     </ul>   <% end -%> </form> 

on submit method create front-end app account controller called. create method front-end app calling create method on rails api responsible updating database , rendering json front end app.

1) accountcontroller#create front-end app :

def create

  # post sur api create account  @response =   httparty.post(env['api_address']+'api/v1/accounts',   :body => { :name => params[:account][:name],              :contact_mail => params[:account][:contact_mail],              :contact_tel =>  params[:account][:contact_tel],              :legal_status => params[:account][:legal_status],              :iban => params[:account][:iban],              :bic => params[:account][:bic]            }.to_json,   :headers => { 'x-user-email' => session[:user_email], 'x-user-token'=> session[:user_token], 'content-type' => 'application/json' } )   # erreur mauvais auth token   if @response["error"] == "you need sign in or sign before continuing."     redirect_to unauthorized_path   # erreur de validation   elsif @response["errors"]     @errors = @response["errors"]     flash[:alert] = "heello"     render :new   else     account_id = @response["account"]["id"]     redirect_to account_path(account_id)   end end 

2) accountcontroller#create api :

def create @account = account.new(account_params.merge(admin: current_user)) authorize @account if @account.save render :show else render_error end end

render error method render errors in json format :

  def render_error     render json: { errors: @account.errors.full_messages }, status: :unprocessable_entity   end 

if there validations errors when submitting api, display them on front end app next form :

 <% if @errors %>         <ul class="list-unstyled">           <%@errors.each |error|%>             <li class="has-error"><%=error%></li>           <% end -%>         </ul> 

my problem wish prepopulate form data user submitted better user experience.

i know there posts how prepopulate forms rails in case of validation errors feel did not address problem "double app pattern" , front-end app not having models (all models / db interactions dealt in api)

how can prepopulate form user's input after receive error json api ?

in form have, add value attributes input fields populate irb instance variables <input type="text" name="account[name]" value="<%= @account_name %>" required>

then in accountcontroller#create, set instance variables based on the params received when want display invalid data.

```

elsif @response["errors"]   @errors = @response["errors"]    #new code   @account_name = params[:account][:name]   #set each variable, method or class cleaner style    flash[:alert] = "heello"   render :new 

```

when form renders these variables uninitialize/nil there no values in form boxes, , can explicitly set them in controller when validation fails want maintain data in form.

this overly-manual way accomplish maintaining form state, , suggest if want reuse pattern in app take @ using form_for. post might give insight doing plain ruby objects instead of model objects. is possible create form simple class