ArgumentError错误的参数数量（1代表3..4）

Question

I get an ArgumentError for line #3 in my views/-/new.html.erb file that states:

"wrong number of arguments (1 for 3..4)"

<div class='form-group'>
    <%= form.label :category %>
    <%= form.select "category", options_from_collection_for_select([{1 => 'Food'}, {2 => 'Entertainment'}]) %>
</div>

The Application trace states:

app/views/events/new.html.erb:14:in block in _app_views_events_new_html_erb__1569841425540097418_70204987081640' app/views/events/new.html.erb:5:in _app_views_events_new_html_erb__1569841425540097418_70204987081640'

erb:14 is line #3 above, and erb:5 is

<%= form_for @event do |form| %>

Answer 1

The error message is being thrown by options_from_collection_for_select([{1 => 'Food'}, {2 => 'Entertainment'}])

[{1 => 'Food'}, {2 => 'Entertainment'}] is an array being passed as one argument to options_from_collection_for_select method; hence the error message.

The correct form for calling the options_from_collection_for_select helper method is

options_from_collection_for_select(collection, value_method, text_method, selected = nil)

See more details and usage examples at http://apidock.com/rails/ActionView/Helpers/FormOptionsHelper/options_from_collection_for_select

Answer 2

I think you'd be better off using options_for_select , which will work with the arguments you've provided and just replace the options_from_collection_for_select in your code. The documentation for which can be found here .

You need to decide whether you want the number (1, 2 etc.) or the word (Food, Entertainment etc.) to be the "value" which reaches your back-end. For example:

options_for_select({'Food' => 1, 'Entertainment' => 2})

The output of the above in HTML would be as follows:

<option value="1">Food</option>
<option value="2">Entertainment</option>

---

The options_from_collection_for_select method requires 3 arguments. You've only provided one: [{1 => 'Food'}, {2 => 'Entertainment'}] . Your second argument should be a method/attribute on each object in the collection which represents the "value", the third should be the label for that value.