Exporting Records To CSV Discussion

Is there some magic happening when you call @users.to_csv ?? As I understand @users is an ActiveRecord::Relation, how is the method 'to_csv' sended to the User class ??

Awesome! I know RailsCast already did this a long time ago, but its great to see it redone with the updates to the syntax.

Newbie question...I have two models a user model and a coupons model that are associated (coupons belong to user). How do I include the export of a parent model (like user.name field) in the CSV attributes?

Hey Chris, Thanks for an amazing video. I had trouble with Ryan Bate's course, but yours works perfectly on rails 4.2

I have a question. I have a table with Invoices (scoped by created desc & limit 10) which represents each row on the csv and a table footer which is an active record calculations for the sum of each attributes. I would like to also place them in the csv but haven't found any resource. Could you give me some hint on how I can implement it?

Thanks alot in advance. I really appreciate your contributions. It has made me learn a bunch!

Is it possible to generate csv without templates, i mean i have some field in page like github repository name and date it got created?

Really Awesome!!!

Very well done.
Can you guide me in the direction of making multiple CSV exports on the same model/controller. I can't seem to figure out how to do more than one query-export...

Any reason why I would prefer CSV over an SQL database? :)

Very helpful, Chris!

One note on something I ran into... I found on a Rails 4.0 app with Ruby 2.0 that naming the method `to_csv` didn't work. The `to_csv` method from the Ruby CSV seemed to override my method and would just kick out a single row with each object in the set. Renaming the method to `export_csv` solved the problem for me.

Clearly something going on that is unusual in my app configuration, because as I understand it, this method should come "first".

Anyhow, working now!

Thank Chris, I found this useful.

I am a little confused. Why can an array of User objects invoke a class method of User class?

If the data I want not come from mysql records, how to do?

The generation of CSV should not be done on the Model, it's part of how the data is displayed or represented, so it's part of the View. Dont you think so?

Using the same code set, how would I go about toggling a boolean field, :exported, at the time of export to csv?

I recently needed to implement something similar to this, but needed to be able to capture the scope passed to the model class and create the CSV based on that scope.

Instead of `all`, use `current_scope` to capture the scope (e.g. `User.where(active: true).limit(10).to_csv`)

https://gist.github.com/mgo...

How attributes will going to help when i need to export relations data as well? If some one any idea, please let me know

Did you have the same `def self.to_csv` function on the model and the controller?

transactions.rb

belongs_to :client
def self.to_csv
attributes = %w{id client_id from_date to_date records }

CSV.generate(headers: true) do |csv|
csv << attributes

all.each do |transaction|
csv << transaction.attributes.values_at(*attributes)
end
end
end
Now I need to add client.name to be printed (since client is the parent )?
is there way to do it or any recommended gem to use?

Thanks for a great episode.
Wanted to give you an example of how to incorporate associated data. The model collection has a partner associated via collection.visit.partner. This csv was setup in the model of collections.
attributes1 is for collection
attributes 2 is for collection.visit.partner
Hope you can use it.

def self.to_csv
attributes1 = %w{quantity size content}
attributes2 = %w{name partner_number address_one postno city}
CSV.generate(headers: true) do |csv|
csv << attributes1 + attributes2
all.each do |collection|
csv << attributes1.map{ |attr| collection.send(attr)} + attributes2.map{ |attr| collection.visit.partner.send(attr)}
end
end
end

HI. I am newbie with rails and trying to export records into a csv. I am able to do the simple download, thanks to this wonderful discussion. But my problem is that instead of all.each, I want to iterate over a subset of records. How can I achieve that? Any help would be appreciated. Thanks

Hi, My .to_csv method looks like this:

def self.to_csv
attributes = %w{stamnummer naam datum vak studierichting }

CSV.generate(headers: true) do |csv|
csv << attributes
all.each do |absence|
csv << [absence.user.ugent_student_id, absence.user.fullname, absence.date.strftime("%d %b %Y"), absence.course.title, absence.study_program]
end
end

The problem I have with this is that when I open the .csv file in Excel, all attributes are placed in one cell, while I expected every attribute to be placed in it's own field.

Do you know ho to implement this?

thanks for your help,

Anthony

This is a great episode, thanks! I am able to do all of this on the index action in the controller I am using to export a csv but when I try to do this on an action which I have called 'annual' I am getting a 404 error as it is trying to run the .to_csv on the #show controller... The action is

def annual
@year = params[:date][:year]
@surveys = Survey.where("year = ?", @year)

respond_to do |format|
format.html # index.html.erb
format.json { render json: @surveys }
format.csv { send_data @surveys.to_csv, filename: "survey-annual-#{Date.today}.csv"}
end
end

I'm at a loss...

Hi Chris! Thanks for this Episode... I think would be great if all the screencast have the source code in github, because sometimes the video explanation is focused in some part of the code, and the other part you've previously wrote. I'll hope that in the most recent episodes the code will be up. For now I have and uninitialized constant User::Import error, and I don't know how to solve. I saw code without explanation in your user_controller.rband I think that my problem is in User::Import but I can't solve the problem :(

Thanks so much for this awesome post and episode. I found it really useful for setting up a CSV export for my Users model. I noticed a couple commenters were having a similiar issue when attempting to do an export with has_many relationships. I couldn't seem to get the suggestion that Chris gave Nathan to work for me, so after a couple hours of mucking around, I sorted it out and wrote something up quickly in case it helps anyone else out. So basically, I'm just showing how you can export Users and their potentially many Coupons in a single shot.

http://blog.blackninjadojo.com/ruby/rails/2019/02/06/exporting-rails-models-with-has-many-relationships-to-csv.html

Thanks again,
Shereen

i have a problem i cant solve.

i have a model and controller for cars, and can export the data i need to a csv, however i have images saved and stored by paperclip. cars has a one to many relationship with the images but i cannt for the life of me figure out how to get the urls for the images from the asset pipeline.

currently i have my csv code in the model for cars and i can get the db data from the images but cant get the url's.

i have no issues creating the csv data from the view or cars controller (Philosophically) other than i cant get it to work. lol

any help is greatly appreciated!

THANKS!
d

This just helped me 4 years later. Thanks, Chris!

Hey Chris. Love the tutorial. Used it with ease on Rails 5.2. Now with webpack and Rails 6.0 I seem to be getting some sort of weird caching issue in production. I made some changes to the attributes, and they don't update on server. I even added a record and it still didn't show up!

Any ideas as to what might be going on and how to fix it? I posted a Stack question with some more code here.
https://stackoverflow.com/questions/61150453/compile-in-rails-6-webpacker-doesnt-make-changes-to-send-data-with-methods-defi?noredirect=1#comment108188144_61150453

Your Uppy tutorial was amazing!