Fix select helper with block returning non-string #51743
Conversation
As suggested by the docs for [FormOptionsHelper#select][1], the helper
can be called with a block to customize option tag attributes:
select(report, :campaign_ids) do
available_campaigns.each do |c|
tag.option(c.name, value: c.id, data: { tags: c.tags.to_json })
end
end
Prior to this commit, a NoMethodError error would be raised when
available_campaigns in the above example was the empty array. This
happened because the block passed to select would return a non-string
value (the empty array) causing the call to capture in
Helpers::Tags::Select#initialize to return nil:
def initialize(object_name, method_name, template_object, choices, options, html_options)
@Choices = block_given? ? template_object.capture { yield || "" } : choices
This commit fixes this by moving the `|| ""` outside the block passed to
capture.
[1]: https://api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html#method-i-select
As requested by RuboCop.
| @post = Post.new | ||
|
|
||
| output_buffer = fields_for :post, @post do |f| | ||
| concat(f.select(:category) { [] }) |
There was a problem hiding this comment.
What's the expectation here, that it'd return an array of choices, rather than option tags? That seems new behavior, can we test that it works like that?
There was a problem hiding this comment.
Great question!
No, the expectation remains the same: the block either outputs several option tags that get captured into the output buffer or returns a string that includes the option tags.
The problem is that when the helper is used as suggested in the docs to output several option tags within a call to each, and available_campaigns is empty, no option tags will be output, and the block will effectively return [] which will cause @choices in ActionView::Helpers::Tags::Select#initialize to be set to nil.
select(report, :campaign_ids) do
available_campaigns.each do |c|
tag.option(c.name, value: c.id, data: { tags: c.tags.to_json })
end
end
This will in turn cause the following error in options_for_select:
NoMethodError: undefined method `map' for nil
lib/action_view/helpers/form_options_helper.rb:365:in `options_for_select'
lib/action_view/helpers/tags/select.rb:28:in `render'
lib/action_view/helpers/form_options_helper.rb:160:in `select'
lib/action_view/helpers/form_options_helper.rb:849:in `select'
test/template/form_options_helper_test.rb:722:in `block in test_select_under_fields_for_with_block_returning_a_non_string_value'
lib/action_view/helpers/capture_helper.rb:50:in `block in capture'
lib/action_view/buffers.rb:75:in `capture'
lib/action_view/helpers/capture_helper.rb:50:in `capture'
lib/action_view/helpers/form_helper.rb:1088:in `fields'
lib/action_view/helpers/form_helper.rb:1031:in `fields_for'
test/template/form_options_helper_test.rb:721:in `test_select_under_fields_for_with_block_returning_a_non_string_value'
Would changing this line to something like this explain the situation better?
| concat(f.select(:category) { [] }) | |
| concat(f.select(:category) { [].each { |title| content_tag(:option, title) }) |
As suggested by the docs for FormOptionsHelper#select, the helper can be called with a block to customize option tag attributes:
Prior to this commit, a NoMethodError error would be raised when available_campaigns in the above example was the empty array. This happened because the block passed to select would return a non-string value (the empty array) causing the call to capture in Helpers::Tags::Select#initialize to return nil:
This commit fixes this by moving the
|| ""outside the block passed to capture.