I got an error while trying to use collection_select ;)
I got this code in my view:
<%= f.collection_select(:channel, :channel_id, #channels, :id, :channelname, prompt: true) %>
in my controller I have this:
#channels = Channel.all
and I got this error:
undefined method `merge' for :channelname:Symbol
Whats my failure ?
Thanks at all!
According to the docs:
collection_select(method, collection, value_method, text_method,
options = {}, html_options = {}) public
So therefore you should use:
<%= f.collection_select(:channel_id, Channel.all, :id, :channelname, prompt: true) %>
You can use like
Channel.all.pluck(:id, :channelname)
For example take look at below
collection_select(
:post, # field namespace
:author_id, # field name
# result of these two params will be: <select name="post[author_id]">...
# then you should specify some collection or array of rows.
# It can be Author.where(..).order(..) or something like that.
# In your example it is:
Author.all,
# then you should specify methods for generating options
:id, # this is name of method that will be called for every row, result will be set as key
:name_with_initial, # this is name of method that will be called for every row, result will be set as value
# as a result, every option will be generated by the following rule:
# <option value=#{author.id}>#{author.name_with_initial}</option>
# 'author' is an element in the collection or array
:prompt => true # then you can specify some params. You can find them in the docs.
)
try this
<%= f.collection_select(:channel_id, :id, prompt: true) %>
Related
Is there any way to use grouped_collection_select value_method with parameters in Rails?
I'm trying to filter out a couple of options based on the current_user (effectively using something like: signed_by(current_user)) but I'm having some difficulty passing it in.
<%= f.grouped_collection_select :author_id, Author.posts, :signed_by, :title, :id, :email %>
Any ideas?
It's not possible to pass parameters to the value_method in this case because the value_method option is "the name of a method which, when called on a child object of a member of collection, returns a value to be used as the contents of its tag". In other words, it's just a string or symbol that will get called on the Author.posts collection.
If you're trying to filter out some options, I would suggest filtering them from the collection, and then passing the filtered collection to this method. Something like:
# author_helper.rb
def filtered_author_posts
Author.posts.where.not(signed_by: current_user)
end
<%= f.grouped_collection_select :author_id, filtered_author_posts, :signed_by, :title, :id, :email %>
For my form, I have this:
<%= tag_field.collection_select( :id, Material.order(:name), :id, :name,
:prompt => "-select-")%>
This prints my materials names.
example:
Cat
Cat
However, this is not helpful because the materials have the same names.
There is another attribute in the Material record, :color.
I want it to print out this in the dropdown
Cat - Brown
Cat - Orange
How do I go about doing this? I tried calling a method instead, but it doesn't print out the way I want it to. Here's what I did.
View:
<%= tag_field.collection_select( :id, Material.order(:name), :id, :something,
:prompt => "-select-")%>
Model:
def something
materials_array = []
Material.all.each do |material|
if material.color == nil
material.name + '-' + material.size
else
materials_array.push(material.name + '-' + material.color)
end
end
materials_array
end
However, the dropdown prints out like this:
["Cat - Brown", "Cat - Orange"]
["Cat - Brown", "Cat - Orange"]
It prints out twice, with the same values. I think I'm close? Please help.
I think it's easier if you use select instead of collection_select. Try it:
<%= tag_field.select :id, Material.order(:name).map{ |m| [ "#{m.name} - #{m. color}", m.id ] }, {prompt: "-select-"} %>
This answer explains clearly the usage of collection_select helper. The method :name_with_initial (which corresponds to the method something in your code) is explained as:
:name_with_initial, # this is name of method that will be called for
# every row, result will be set as value
# as a result, every option will be generated by the following rule:
# <option value=#{author.id}>#{author.name_with_initial}</option>
# 'author' is an element in the collection or array
So if you are getting results twice it means the collection/array has redundant values.
I have this collection_select <%= collection_select(:template, :template_id, #templates, :id, :name) %> and I want to basically call :name.humanize, but obviously that doesn't work.
How can i call a method such as .humanize on an attribute of collection_select (a hash attribute?)
EDIT
Here's a snippet from my controller:
#templates = Template.select(:name).group(:name)
p "templates = #{#templates}"
Here's what appears in the console:
"templates = #<ActiveRecord::Relation:0x007f84451b7af8>"
With Rails 4
Just like this:
<%= collection_select(:template, :template_id, #templates, :id, Proc.new {|v| v.name.humanize}) %>
In the Proc block, v will be your models, iterated through a each loop.
collection_select works with anything that inherit from Enumerable and have no limit in the content of the Proc.
With Rails 3
You must do it your self, by preparing your data before passing it to collection_select
# This will generate an Array of Arrays
values = #templates.map{|t| [t.id, t.name.humanize]}
# [ [record1.id, record1.name.humanize], [record2.id, record2.name.humanize], ... ]
# This will use the Array previously generated, and loop in it:
# - send :first to get the value (it is the first item of each Array inside the Array)
# - send :last to get the text (it is the last item of each Array inside the Array)
# ( we could have use :second also )
<%= collection_select(:template, :template_id, values, :first, :last) %>
I have multiple identical collection selects inside a single form. I prefer this over a multiple select list for aesthetic and UX reasons. I have to use a terrible kludge to make everything work right, and I'm wondering if there is a more elegant way to do this:
From the view:
<% 3.times do |i| %>
<%= collection_select("selected_item_" + i.to_s.to_s, :name, #items, :name, :name, { :include_blank => true }, { id: "selected_item_" + i.to_s }) %>
<% end %>
From the controller:
ItemContainer = Struct.new(:name)
3.times do |i|
param = ('selected_item_' + i.to_s).to_sym
instance_variable = '#' + param_name
if params[param] && !params[param].empty?
#selected_items << params[param][:name]
instance_variable_set(instance_variable, ItemContainer.new(params[param][:name]))
end
end
#selected_channels.each.... # do what I need to with these selections
Most of these gymnastics are needed to ensure that the item is still selected if the page is refreshed. If there were some way to force collection select to use arrays, that would be the answer, but I couldn't make that work.
If I understang right you're looking for selegt_tag method (docs: http://api.rubyonrails.org/classes/ActionView/Helpers/FormTagHelper.html#method-i-select_tag)
You can write something like this
select_tag "people[]", options_from_collection_for_select(#people, "id", "name")
select_tag "people[]", options_from_collection_for_select(#people, "id", "name")
and it youd output two selects for people, which would be sent as an array on submit.
if you use the [] naming in your collection_select calls then the params will send over the data as an array
I am a bit confused as to the usage of collection_select here as it doesn't seem like you are using a model object? this example using select_tag - might be able to come up with something more appropriate to your issue if the model structures were known
# run this in the loop
# set selected_value to appropriate value if needed to pre-populate the form
<%= select_tag('name[]',
options_from_collection_for_select(#items, 'name', 'name', selected_value),
{ include_blank: true }
)
%>
in controller update/create action
# this works because the select tag 'name' is named with [] suffix
# but you have to ensure it is set to empty array if none are passed, usually only issue with checkboxes
names = params[:name] || []
names.each do |name|
puts name
end
side note: you can use string interpolation with ruby double quotes in places of + for string concatenation
<%= collection_select("selected_item_#{i}",
:name,
#items,
:name,
:name,
{ include_blank: true },
{ id: "selected_item_#{i}" }
)
%>
see also: http://apidock.com/rails/v3.2.13/ActionView/Helpers/FormOptionsHelper/options_from_collection_for_select
I am going through the Rails API docs for collection_select and they are god-awful.
The heading is this:
collection_select(object, method, collection, value_method, text_method, options = {}, html_options = {})
And this is the only sample code they give:
collection_select(:post, :author_id, Author.all, :id, :name_with_initial, :prompt => true)
Can someone explain, using a simple association (say a User has_many Plans, and a Plan belongs to a User), what I want to use in the syntax and why?
Edit 1: Also, it would be awesome if you explained how it works inside a form_helper or a regular form. Imagine you are explaining this to a web developer that understands web development, but is 'relatively new' to Rails. How would you explain it?
collection_select(
:post, # field namespace
:author_id, # field name
# result of these two params will be: <select name="post[author_id]">...
# then you should specify some collection or array of rows.
# It can be Author.where(..).order(..) or something like that.
# In your example it is:
Author.all,
# then you should specify methods for generating options
:id, # this is name of method that will be called for every row, result will be set as key
:name_with_initial, # this is name of method that will be called for every row, result will be set as value
# as a result, every option will be generated by the following rule:
# <option value=#{author.id}>#{author.name_with_initial}</option>
# 'author' is an element in the collection or array
:prompt => true # then you can specify some params. You can find them in the docs.
)
Or your example can be represented as the following code:
<select name="post[author_id]">
<% Author.all.each do |author| %>
<option value="<%= author.id %>"><%= author.name_with_initial %></option>
<% end %>
</select>
This isn't documented in the FormBuilder, but in the FormOptionsHelper
I've spent quite some time on the permutations of the select tags myself.
collection_select builds a select tag from a collection of objects. Keeping this in mind,
object : Name of the object. This is used to generate the name of the tag, and is used to generate the selected value. This can be an actual object, or a symbol - in the latter case, the instance variable of that name is looked for in the binding of the ActionController (that is, :post looks for an instance var called #post in your controller.)
method : Name of the method. This is used to generate the name of the tag.. In other words, the attribute of the object you are trying to get from the select
collection : The collection of objects
value_method : For each object in the collection, this method is used for value
text_method : For each object in the collection, this method is used for display text
Optional Parameters:
options : Options that you can pass. These are documented here, under the heading Options.
html_options : Whatever is passed here, is simply added to the generated html tag. If you want to supply a class, id, or any other attribute, it goes here.
Your association could be written as:
collection_select(:user, :plan_ids, Plan.all, :id, :name, {:prompt => true, :multiple=>true })
With regards to using form_for, again in very simple terms, for all tags that come within the form_for, eg. f.text_field, you dont need to supply the first (object) parameter. This is taken from the form_for syntax.