Rails: Form Select From Array/List Instance Variable

Question

I have a rails app where in a form, I have a form select (drop down list). For example the user can select from 1,2,3,4,5

Say for example I had these values stored in an array as an instance variable like:

@formlist = [1,2,3,4,5]

How can I simply put the array into the form select helper rather than listing each item separately. At the moment my code is:

<tr>
  <th><%= f.label(:heat_level, "Heat Level") %></th>
  <td><%= f.select(:heat_level,{ 1 => "1", 2 => "2", 3 => "3", 4 => "4", 5 => "5"}) %></td>
</tr>

Vlad Khomich · Accepted Answer · 2012-11-20 15:01:21Z

19

this should work:

f.select(:heat_level, @formlist.map { |value| [ value, value ] })

some explanation:

form select can handle both hash-like and array-like options list. Meaning, both { 1 => "1", 2 => "2", 3 => "3", 4 => "4", 5 => "5"}

and

[[1, 1], [2, 2], [3, 3], [4, 4], [5, 5]]

will work.

@formlist.map { |value| [ value, value ] } does the latter

answered Nov 20, 2012 at 15:01

Vlad Khomich

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1 Comment

TheRealMrCrowley Over a year ago

Just want to update for future users, the mapping is totally unnecessary for shallow arrays f.select(:heat_level, @formlist) is gonna give you the exact same result

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