Rails select helper - Default selected value, how?

Here is a piece of code I'm using now:

<%= f.select :project_id, @project_select %>

How to modify it to make its default value equal to to params[:pid] when page is loaded?

This should do it:

<%= f.select :project_id, @project_select, :selected => params[:pid] %>

Use the right attribute of the current instance (e.g. @work.project_id):

<%= f.select :project_id, options_for_select(..., @work.project_id) %>

Rails 3.0.9

select options_for_select([value1, value2, value3], default)

The problem with all of these answers is they set the field to the default value even if you're trying to edit your record.

You need to set the default to your existing value and then only set it to the actual default if you don't have a value. Like so:

f.select :field, options_for_select(value_array, f.object.field || default_value)

For anyone not familiar with f.object.field you always use f.object then add your field name to the end of that.

Try this:

    <%= f.select :project_id, @project_select, :selected => f.object.project_id %>

if params[:pid] is a string, which if it came from a form, it is, you'll probably need to use

params[:pid].to_i  

for the correct item to be selected in the select list

I've found solution and I found that I'm pretty unexperienced in RoR.

Inside the controller that manages view described above add this:

@work.project_id = params[:pid] unless params[:pid].nil?

<%= f.select :project_id, @project_select, :selected => params[:pid] %>

I couldn't get this to work and found that I needed to add the "selected" html attribute not only to the correct <option> tag but also to the <select> tag. MDN's docs on the selected attribute of the select tag say:

> selected - Boolean attribute indicates that a specific option can be initially selected.

That means the code should look like:

f.select :project_id, options_for_select(@project_select, default_val), html: {selected: true}

<%= f.select :project_id, options_from_collection_for_select(@project_select,) %>

Its already explained, Will try to give an example

let the select list be

select_list = { eligible: 1, ineligible: 0 }

So the following code results in

<%= f.select :to_vote, select_list %>

<select name="to_vote" id="to_vote">
  <option value="1">eligible</option>
  <option value="0">ineligible</option>
</select>

So to make a option selected by default we have to use selected: value.

<%= f.select :to_vote, select_list, selected: select_list.can_vote? ? 1 : 0 %>

if can_vote? returns true it sets selected: 1 then the first value will be selected else second.

select name="driver[bca_aw_eligible]" id="driver_bca_aw_eligible">
  <option value="1">eligible</option>
  <option selected="selected" value="0">ineligible</option>
</select>

if the select options are just a array list instead of hast then the selected will be just the value to be selected for example if

select_list = [ 'eligible', 'ineligible' ]

now the selected will just take

<%= f.select :to_vote, select_list, selected: 'ineligible' %>

Mike Bethany's answer above worked to set a default value when a new record was being created and still have the value the user selected show in the edit form. However, I added a model validation and it would not let me submit the form. Here's what worked for me to have a model validation on the field and to show a default value as well as the value the user selected when in edit mode.

  <div class="field">
    <%= f.label :project_id, 'my project id', class: "control-label" %><br>
    <% if @work.new_record? %>
      <%= f.select :project_id, options_for_select([['Yes', true], ['No', false]], true), {}, required: true, class: "form-control" %><br>
    <% else %>
      <%= f.select :project_id, options_for_select([['Yes', true], ['No', false]], @work.project_id), {}, required: true, class: "form-control" %><br>
    <% end %>
  </div>

model validation

  validates :project_id, presence: true

Alternatively, you could set the :project_id attribute in the controller, since the first argument of f.select pulls that particular attribute.

If try to print the f object, then you will see that there is f.object that can be probed for getting the selected item (applicable for all rails version > 2.3)

logger.warn("f #{f.object.inspect}")

so, use the following script to get the proper selected option:

:selected => f.object.your_field 

This should work for you. It just passes {:value => params[:pid] } to the html_options variable.

<%= f.select :project_id, @project_select, {}, {:value => params[:pid] } %>