Include the Table Name In the Rails options_for_select Form Helper

In a Rails application, I have an advanced search form that allows the user to select any column from the database to search on. This is currently set up to use an HTML select element with all of the column names listed as option elements.

To make my searching easier, I wanted to show just the name of the column in the option element but have it return the name of the parent table and the column name. For instance, I wanted the HTML to look like the following:

<select>
<option value="my_table.column_name">Column name</option>
</select>

The Rails API documentation shows many examples of using collection of objects from a model etc., but I couldn't find any examples using the column names from the model. So, after many failed attempts, I finally managed to get this syntax to work:


<%= options_for_select(MyTable.column_names.collect {|col| [col, "my_table." + col]} %>


In this example, I grab the column names using the built-in Rails method, then pass that array of strings to Ruby's collect method. The collect method accepts a block that allows me to create a new array where each element is itself an array. In these smaller arrays, I insert the column name directly and a string with the table name added to the beginning. The array created by the collect method is now of the proper format expected by the Rails options_for_select form helper.

I didn't think it would be this difficult, but in the end, I think the single line of code is pretty clean and simple.

Update
Well, I guess my idea wasn't that new and cool. As soon, as I posted this, I found the same solution in the API docs after all. I was just looking in the options_for_select section, not the select selection. See:

http://api.rubyonrails.com/classes/ActionView/Helpers/FormOptionsHelper.html#M001592