Beginner: Finding an image path - ruby-on-rails

Hello and sorry for such a basic question, but I have exhausted all search options.
My question is how do I find an image path? I am starting to learn Ruby on Rails and a gem I am trying to integrate requires me to specify an image path:
colors = Miro::DominantColors.new('/path/to/local/image.jpg')
How do I find the path to a local image saved to my desktop?
I am trying to use the Miro RoR gem (https://github.com/jonbuda/miro).
Thank yo,
Brian

You're going to have to upload the image
Images
The problem you've got is Rails is server-side
You're trying to load an image from your client-side system (your desktop)
This means that in order to get Rails to process the image in any way, you will have to first upload the image into the system, then process it. The recommended way to do this is to use the Paperclip gem (for image uploads), then you can use your Miro gem to process the image
Here's what I'd do:
Upload
You'll first have to upload the image
There are numerous ways to do this, but the process is the same:
Create image model & db (to store the image)
Create upload form
Process upload through controller
Model
#app/models/image.rb
Class Image < ActiveRecord::Base
has_attached_file :image
end
Controller
#app/controllers/images_controller.rb
def new
#image = Image.new
end
def create
#image = Image.new(image_params)
#image.save
end
private
def image_params
params.require(:image).permit(:image)
end
View
#app/views/images/new.html.erb
<%= form_for #image do |f| %>
<%= f.file_field :image %>
<% end %>
Process
After saving the image, you can then call one of Paperclip's processing methods to manage the uploaded image's processing. Here are some ideas on how you may do this:
Paperclip Processing Tutorial
Paperclip Image Processing using DelayedJob

Thanks for the advice and links to paperclip tutorials, Rich. I'll definitely be using those resources in the near future.
The solution was too simple, and I feel guilty for asking the question haha. All I had to do was use terminal to navigate to the image then just $pwd to get the path.

Related

Saving image created with RMagick using Rails and CarrierWave

In my Rails app I have a module that takes several images, and using RMagick "stitches" them together into a new single image. I'm able to successfully create the final image, but I'm having trouble saving this new image as an attachment to a model (using CarrierWave). The method that does the stitching looks like this:
def generate_collage(params)
final_image = ImageList.new
# ... code that puts together the composite image ...
return final_image.append(true).to_blob { |attrs| attrs.format = 'JPEG' }
end
I've got my User model with an uploader mounted:
class User < ActiveRecord::Base
mount_uploader :image, UserImageUploader
end
In the CarrierWave documentation under the ActiveRecord section, they show how to assign a new image, but they assume the file already exists somewhere. In my case it doesn't yet exist on the filesystem, and I'm outputting a blob... is there any way to go from that blob to generating an image upload for CarrierWave?
I suppose I'm trying to avoid saving this image temporarily into "#{Rails.root}/tmp/" and then reading it from there... it seems like I could cut out this step and send directly to CarrierWave somehow, but I don't know how! Is it possible?
I'm working on something similar right now. This should be possible, but an easy workaround is to save it to a temp file:
temp_file = Tempfile.new([ 'temp', '.png' ])
image.write(temp_file.path)
user = User.new
user.avatar = temp_file
user.save
temp_file.close
temp_file.unlink
I'm hoping to try to improve it to remove the file system dependency completely, by following the advice in one of these answers: How to handle a file_as_string (generated by Prawn) so that it is accepted by Carrierwave?

Rails If - Else Statement image_url to check existence

<div class="img-container">
<%= if #user.image_url.present? %>
<%= image_tag #user.image_url(:main).to_s %>
<%= end %>
</div>
I am using rails 4, and carrier wave to upload photos as mentioned in the rails casts. So I have a column in my db that is called "image", and the above code works without the if statement. When I use the #user.image_url(:main).to_s and it has an image it properly shows the image in the container. I want to upload a standard photo when the user does not provide one. It's located in my assets/images folder.
How can I get the if statement to detect if there is photo present or not in the column image? I have to use image_url if showing the user uploaded photo. Not just image to display the image, and the .to_s is a safety net. Any thoughts or answers?
Thanks!
Thanks to the accepted answer, I did use the suggested carrier wave solution for Rails 4 which is recommended for 3.1 and above. This post helped me get it corrected: Default URL not loading with Carrierwave in Rails
Specifying a default url with CarrierWave should do the trick. This allows for a fallback if no image is currently present.
Example:
def default_url
ActionController::Base.helpers.asset_path "fallback/main/default.jpg"
end
For Rails 5 the one that worked for me is
ActionController::Base.helpers.resolve_asset_path("logos/smthg.png")
returns nil if the asset is absent
and
the asset path if present
👍

Uploading a file in Rails

I'm new to rails, and I'm writing a RESTful website using the CRUD technique. So far I have created three pages, all of which allow the user to create, edit, and delete a row from the database. However, my fourth page will need to include an upload file form, but a) I don't know how the filesystem works with Rails thus I don't know where files should be stored. The file would be around 100kb and couldn't be stored in temporary storage because it will be constantly downloaded. And b) I don't know how to write to a file.
It would be great if you could tell me how to do what I mentioned above - create an upload input on an input form, and to then write the file to a filepath in a separate directory.
Update 2018
While everything written below still holds true, Rails 5.2 now includes active_storage, which allows stuff like uploading directly to S3 (or other cloud storage services), image transformations, etc. You should check out the rails guide and decide for yourself what fits your needs.
While there are plenty of gems that solve file uploading pretty nicely (see https://www.ruby-toolbox.com/categories/rails_file_uploads for a list), rails has built-in helpers which make it easy to roll your own solution.
Use the file_field-form helper in your form, and rails handles the uploading for you:
<%= form_for #person do |f| %>
<%= f.file_field :picture %>
<% end %>
You will have access in the controller to the uploaded file as follows:
uploaded_io = params[:person][:picture]
File.open(Rails.root.join('public', 'uploads', uploaded_io.original_filename), 'wb') do |file|
file.write(uploaded_io.read)
end
It depends on the complexity of what you want to achieve, but this is totally sufficient for easy file uploading/downloading tasks. This example is taken from the rails guides, you can go there for further information: http://guides.rubyonrails.org/form_helpers.html#uploading-files
Sept 2018
For anyone checking this question recently, Rails 5.2+ now has ActiveStorage by default & I highly recommend checking it out.
Since it is part of the core Rails 5.2+ now, it is very well integrated & has excellent capabilities out of the box (still all other well-known gems like Carrierwave, Shrine, paperclip,... are great but this one offers very good features that we can consider for any new Rails project)
Paperclip team deprecated the gem in favor of the Rails ActiveStorage.
Here is the github page for the ActiveStorage & plenty of resources are available everywhere
Also I found this video to be very helpful to understand the features of Activestorage
There is a nice gem especially for uploading files : carrierwave. If the wiki does not help , there is a nice RailsCast about the best way to use it . Summarizing , there is a field type file in Rails forms , which invokes the file upload dialog. You can use it , but the 'magic' is done by carrierwave gem .
I don't know what do you mean with "how to write to a file" , but I hope this is a nice start.
Okay. If you do not want to store the file in database and store in the application, like assets (custom folder), you can define non-db instance variable defined by attr_accessor: document and use form_for - f.file_field to get the file,
In controller,
#person = Person.new(person_params)
Here person_params return whitelisted params[:person] (define yourself)
Save file as,
dir = "#{Rails.root}/app/assets/custom_path"
FileUtils.mkdir(dir) unless File.directory? dir
document = #person.document.document_file_name # check document uploaded params
File.copy_stream(#font.document, "#{dir}/#{document}")
Note, Add this path in .gitignore & if you want to use this file again add this path asset_pathan of application by application.rb
Whenever form read file field, it get store in tmp folder, later you can store at your place, I gave example to store at assets
note: Storing files like this will increase the size of the application, better to store in the database using paperclip.
In your intiallizer/carrierwave.rb
if Rails.env.development? || Rails.env.test?
config.storage = :file
config.root = "#{Rails.root}/public"
if Rails.env.test?
CarrierWave.configure do |config|
config.storage = :file
config.enable_processing = false
end
end
end
use this to store in a file while running on local

How do you access the raw content of a file uploaded with Paperclip / Ruby on Rails?

I'm using Paperclip / S3 for file uploading. I upload text-like files (not .txt, but they are essentially a .txt). In a show controller, I want to be able to get the contents of the uploaded file, but don't see contents as one of its attributes. What can I do here?
attachment_file_name: "test.md", attachment_content_type: "application/octet-stream", attachment_file_size: 58, attachment_updated_at: "2011-06-22 01:01:40"
PS - Seems like all the Paperclip tutorials are about images, not text files.
In Paperclip 3.0.1 you could just use the io_adapter which doesn't require writing an extra file to (and removing from) the local file system.
Paperclip.io_adapters.for(attachment.file).read
#jon-m answer needs to be updated to reflect the latest changes to paperclip, in order for this to work needs to change to something like:
class Document
has_attached_file :revision
def revision_contents(path = 'tmp/tmp.any')
revision.copy_to_local_file :original, path
File.open(path).read
end
end
A bit convoluted as #jwadsack mentioned using Paperclip.io_adapters.for method accomplishes the same and seems like a better, cleaner way to do this IMHO.
To access the file you can use the path method:
csv_file.path
http://rdoc.info/gems/paperclip/Paperclip/Attachment#path-instance_method
This can be used along with for example the CSV reader.
Here's how I access the raw contents of my attachment:
class Document
has_attached_file :revision
def revision_contents
revision.copy_to_local_file.read
end
end
Please note, I've omitted my paperclip configuration options and any sort of error handling.
You would need to load the contents of the file (using Rubys File.open) into a variable before you show it. This may be an expensive operation if your app gets lots of use, so it may be worthwhile reading the contents of the file and putting it into a text column in your database after uploading it.
Attachment already inherits from IOStream. http://rdoc.info/github/thoughtbot/paperclip/master/Paperclip/Attachment
So it should just be "#{attachment}" or <% RDiscount.new(attachment).to_html %> or send_data(attachment). However you wanted to display the data.
This is a method I used for upload from paperclip to active storage and should provide some guidance on temporarily working with a file in memory. Note: This should only be used for relatively small files.
Written for gem paperclip 6.1.0
Where I have a simple model
class Post
has_attached_file :image
end
Working with a temp file in ruby so we do not have to worry about closing the file
Tempfile.create do |tmp_file|
post.image.copy_to_local_file(nil, tmp_file.path)
post.image_temp.attach(
io: tmp_file,
filename: post.image_file_name,
content_type: post.image_content_type
)
end

Paperclip: How to store a picture in a Rails console?

I tried storing a local image in a rails console.
Because I have many pictures in my local storage (I use crawler to download tons of pictures), I want to store them into a database, with the benefit of paperclip to do some image job, like thumbnail etc.
If I use a webpage to save new pictures to database one by one, it will cost a lot of time. So I want to find a way in rails console (some code) that can batch save-picture-into-database.
To further clarify #andrea's answer:
YourPaperclippedModelHere.new(:your_paperclip_field => File.new(path, "r"))
So if your model is called Image and your paperclip field is data:
Image.new(:data => File.new(path_to_your_file, "r"))
If this is the model:
class User < ActiveRecord::Base
has_attached_file :avatar
end
then the following should work from the console:
>> User.create(:avatar => File.open('/path/to/image.jpg', 'rb'))
I dont know if it is what you want ... but
to save an paperclip asset from console
You could simple use a File instance .
a.e.
Image.new :data=>File.new("/path/to/image.jpg","r")
Late Answer but hopefully it will work for others.
You need to include.
File.new("#{Rails.root}/public/images/default_avatar.png", "r")

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