Question

I want to input selections and input it into micropost table. The selections is from categories table. It encounter problem of category column of micropost is blank so I suspect it cannot input data into the table micropost column of category. I search all the select, select_tag but cannot solve it… Is there anything I miss out?

<%= form_for @micropost do |f| %>
<%= render 'shared/error_messages', :object => f.object %>
<%= f.label :title %><br />
<%=h f.text_field :title %><br />

<%= f.label :content %><br />
<%=h f.text_area :content, :row => 30, :cols=> 30 %><br />

<%  @category = Category.select("category").group("category")
    cat = @category.map{|u| u.category}
%>
    <%= select_tag :category, options_for_select(cat) %>


<%= f.submit "Post" %>

<% end %>

Answer 1

If you check your query you should see that parameter category is sent separately from micropost attributes because

<%  
  @category = Category.select("category").group("category")
  cat = @category.map{|u| u.category}
%>
<%= select_tag :category, options_for_select(cat) %>

generates field inside form with name category not micropost[category] to fix it you can use select instead

 <%  
   cat = Category.select( "category" ).group( "category" ).map( &:category )
 %>
 <%= select :micropost, :category, options_for_select( cat ) %>