I have a form being submitted that is saving multiple records, and the parameters look something like this:
{
"utf8"=>"✓",
"_method"=>"put",
"products"=> {
"321" => {
"sale_price"=>"10"
},
"104" => {
"sale_price"=>"10"
}
}
}
Then in my controller, I have this:
#updated_products = Product.update(params[:products].keys, params[:products].values)
This expects the keys (321, 104) to be IDs.
However, I'm using the to_param in my model to change my urls from IDs to another column value.
Is there a way to take the params[:products].keys and swap them for the appropriate IDs so I can use IDs in the .update() statement.
I can use Product.find_by_column_name(321).id to get the id although I don't know how to do this. Still new to rails.
Any help would be appreciated. Thanks.
Looking at the source code here #update iterates through each key and runs update_attributes so it goes through all the validations. You can change your method to
#updated_products = params[:products].inject([]) do |array, (column_id, attributes)|
product = Product.find_by_column_id column_id
if product.update_attributes(attributes)
array << product
else
array
end
end
This may seem a little complex but it is equal to this one below which is easier to understand and code read
#updated_products = []
params[:products].each do |column_id, attributes|
product = Product.find_by_column_id column_id
if product.update_attributes(attributes)
#updated_products << product
end
end
Related
The model User has first, last and login as attributes. It also has a method called name that joins first and last.
What I want is to iterate through the Users records and create an array of hashes with the attributes I want. Like so:
results = []
User.all.map do |user|
record = {}
record["login"] = user.login
record["name"] = user.name
results << record
end
Is there a cleaner way in Ruby to do this?
Trying to map over User.all is going to cause performance issues (later, if not now). To avoid instantiating all User objects, you can use pluck to get the data directly out of the DB and then map it.
results = User.all.pluck(:login, :first, :last).map do |login, first, last|
{ 'login' => login, 'name' => first << last }
end
Instantiating all the users is going to be problematic. Even the as_json relation method is going to do that. It may even be a problem using this method, depending on how many users there are.
Also, this assumes that User#name really just does first + last. If it's different, you can change the logic in the block.
You can use ActiveRecord::QueryMethods#select and ActiveRecord::Relation#as_json:
User.select(:login, '(first || last) as name').as_json(except: :id)
I would write:
results = User.all.map { |u| { login: u.login, name: u.name } }
The poorly named and poorly documented method ActiveRecord::Result#to_hash does what you want, I think.
User.select(:login, :name).to_hash
Poorly named because it does in fact return an array of Hash, which seems pretty poor form for a method named to_hash.
Assume we have a rails params hash full of nested hashes and arrays. Is there a way to alter every string value (whether in nested hashes or arrays) which matches a certain criteria (e.g. regex) and still keep the output as a params hash (still containing nested hashes arrays?
I want to do some sort of string manipulation on some attributes before even assigning them to a model. Is there any better way to achieve this?
[UPDATE]
Let's say we want to select the strings that have an h in the beginning and replace it with a 'b'. so we have:
before:
{ a: "h343", b: { c: ["h2", "s21"] } }
after:
{ a: "b343", b: { c: ["b2", "s21"] } }
For some reasons I can't do this with model callbacks and stuff, so it should have be done before assigning to the respective attributes.
still keep the output as a params hash (still containing nested hashes arrays
Sure.
You'll have to manipulate the params hash, which is done in the controller.
Whilst I don't have lots of experience with this I just spent a bunch of time testing -- you can use a blend of the ActionController::Parameters class and then using gsub! -- like this:
#app/controllers/your_controller.rb
class YourController < ApplicationController
before_action :set_params, only: :create
def create
# Params are passed from the browser request
#model = Model.new params_hash
end
private
def params_hash
params.require(:x).permit(:y).each do |k,v|
v.gsub!(/[regex]/, 'string')
end
end
end
I tested this on one of our test apps, and it worked perfectly:
--
There are several important points.
Firstly, when you call a strong_params hash, params.permit creates a new hash out of the passed params. This means you can't just modify the passed params with params[:description] = etc. You have to do it to the permitted params.
Secondly, I could only get the .each block working with a bang-operator (gsub!), as this changes the value directly. I'd have to spend more time to work out how to do more elaborate changes.
--
Update
If you wanted to include nested hashes, you'd have to call another loop:
def params_hash
params.require(:x).permit(:y).each do |k,v|
if /_attributes/ ~= k
k.each do |deep_k, deep_v|
deep_v.gsub!(/[regex]/, 'string'
end
else
v.gsub!(/[regex]/, 'string')
end
end
end
In general you should not alter the original params hash. When you use strong parameters to whitelist the params you are actually creating a copy of the params - which can be modified if you really need to.
def whitelist_params
params.require(:foo).permit(:bar, :baz)
end
But if mapping the input to a model is too complex or you don't want to do it on the model layer you should consider using a service object.
Assuming you have a hash like this:
hash = { "hello" => { "hello" => "hello", "world" => { "hello" => "world", "world" => { "hello" => "world" } } }, "world" => "hello" }
Then add a function that transforms the "ello" part of all keys and values into "i" (meaning that "hello" and "yellow" will become "hi" and "yiw")
def transform_hash(hash, &block)
hash.inject({}){ |result, (key,value)|
value = value.is_a?(Hash) ? transform_hash(value, &block) : value.gsub(/ello/, 'i')
block.call(result, key.gsub(/ello/, 'i'), value)
result
}
end
Use the function like:
new_hash = transform_hash(hash) {|hash, key, value| hash[key] = value }
This will transform your hash and it's values regardless of the nesting level. However, the values should be strings (or another Hash) otherwise you'll get an error. to solve this problem just change the value.is_a?(Hash) conditional a bit.
NOTE that I strongly recommend you NOT to change the keys of the hash!
I have an array with model attributes (these model attributes are columns in DB table). I am trying to iterate through this array and automatically create a record which I would like to save to DB table, something like this:
columns.each_with_index do |c, i|
user.c = data[i]
puts user.c
end
user is model.
But if I try the snippet above, I get
undefined method `c=' for #<User:0x007f8164d1bb80>
I've tried also
columns.each_with_index do |c, i|
user."#{c}" = data[i]
puts user."#{c}"
end
But this doesn't work as well.
Data in columns array are taken from form that sends user, so I want to save only data that he send me, but I still cannot figure it out...
I would like to ask you for help... thank you in advance!
user.send("#{c}=".to_sym, data[i])
Also, you can access the attributes as a hash.
user.attributes[c] = data[i]
The best thing would probably be to build a hash and to use update_attributes:
mydata = {}
columns.each_with_index{|c, i| mydata[c] = data[i]}
user.update_attributes(mydata)
this way you retain the protections provided by attr_accessible.
If this is actually in a controller, you can just make use of some basic rails conventions and build the User record like this:
#user = User.new(params[:user])
if #user.save
# do something
else
# render the form again
end
Although you can set the values using send, I agree with #DaveS that you probably want to protect yourself via attr_accessibles. If your planning to use Rails 4, here's a good overview.
I want to extract the id number of a unique record, that resides in a different controller as an integer, so I can save it as part of a new record in a new controller.
I can't seem to get the id to shed it's 'Array' attribute.
I've been using this:
class MessagesController < ApplicationController
def incoming
a = Group.where("name = ?", name).map { |n| n.id }
group_number = a.id
puts "#{group_number} is the number!"
end
output is always [2] or [3] or whatever.
adding this doesn't seem to cure it
group_as_int = group_number.to_i
Lastly, the reason I'm doing all this is to save that group number as a new record in a third controller, like this:
Subscriber.create(:group_id => group_number, :active => "1")
or
Subscriber.create(:group_id => group_as_int, :active => "1")
Of course, the create balks when I try to pass an array into the create function.
Thoughts?
You are trying to put business logic into the controller.
Try to refactor your methods and put them into your models instead.
Beside that you get the number in the following way:
group = Group.where("name = ?", name).first
group_number = group.id if group.present?
You might want to try .first to get the integer out of the array.
I will try to explain from your code what you did wrong.
The first line:
matching_group_ids = Group.where("name = ?", name).map { |n| n.id }
You called it a, but i prefer more verbose names. matching_group_ids now holds an array of id's. To get the first value of this array, the easiest solution is to just write
group_number = matching_group_ids[0]
or, more readable:
group_number = matching_group_ids.first
Mind you: you should test that the returned array is not empty.
Hope this helps.
This question is quite simple but I have run into the problem a few times.
Let's say you do something like:
cars = Vehicle.find_by_num_wheels(4)
cars.each do |c|
puts "#{c.inspect}"
end
This works fine if cars is an array but fails if there is only one car in the database. Obviously I could do something like "if !cars.length.nil?" or check some other way if the cars object is an array before calling .each, but that is a bit annoying to do every time.
Is there something similar to .each that handles this check for you? Or is there an easy way to force the query result into an array regardless of the size?
You might be looking for
cars = Vehicle.find_all_by_num_wheels(4)
The dynamic find_by_ methods only return one element and you have to use find_all_by_ to return multiple.
If you always want all of the cars, you should use find_all instead:
cars = Vehicle.find_all_by_num_wheels(4)
You could also turn a single Vehicle into an array with:
cars = [cars] unless cars.respond_to?(:each)
Named scoped version for your problem
Vehicle.scoped(:conditions => { :num_wheels => 4 } ).each { |car| car.inspect }
You can do this to get arrays everytimes :
cars = Vehicle.find(:all, :conditions => {num_wheels => 4})
I don't think that you have a loop that will check if the object is an array.
Another solution could be:
for i in (1..cars.lenght)
puts cars[i].inspect
end
(haven't tested, it might break to test the lenght on a string. Let me know if it does)