I need to upload an image from a rails form using Ajax and convert it into a byte array to show a html preview of the image.
When I read the file, it returns me binary data which is not readable by img tag. I'm sure I'm doing something very silly and this might have an obvious solution. Here is the code snippet. Please help.
rails
tmp = File.open(params[:file_upload][:my_file].tempfile, 'rb').read
render :text => tmp
jquery
$("#item_detail_image").attr("src", "data:image/png;base64," + data.responseText);
I'm not using paperclip because I don't have a database connection to my rails application (I'm using web services) and I'm not sure how to use paperclip without ActiveRecord
You need to Base 64 encode the data.
See http://www.ruby-doc.org/stdlib-1.9.3/libdoc/base64/rdoc/Base64.html#method-i-encode64
Related
I have a CSV file that I'm uploading which runs into an issue when importing rows into the database:
Encoding::UndefinedConversionError ("\xCC" from ASCII-8BIT to UTF-8)
What would be the most efficient way to ensure each column is properly encoded for being placed in the database or ignored?
The most basic approach is to go through each row and each field and force encoding on the string but that seems incredibly inefficient. What would be a better way to handle this?
Currently it's just uploaded as a parameter (:csv_file). I then access it as follows:
CSV.parse(csv_file.download) within the model.
I'm assuming there's a way to force the encoding when CSV.parse is called on the activestorage file but not sure how. Any ideas?
Thanks!
The latest version ActiveStorage (6.0.0.rc1) adds an API to be able to download the file to a temp file, which you can then read from. I'm assuming that Ruby will read from the file using the correct encoding.
https://edgeguides.rubyonrails.org/active_storage_overview.html#downloading-files
If you don't want to upgrade to the RC of Rails 6 (like I don't) you can use this method to convert the string to UTF-8 while getting rid of the byte order mark that may be present in your file:
wrongly_encoded_string = active_record_model.attachment.download
correctly_encoded_string = wrongly_encoded_string.bytes.pack("c*").force_encoding("UTF-8")
I am using the Carrierwave gem to upload attachments to my model. I added elasticsearch with the mapper attachments plugin to allow for full text search of the attachments.
Carrierwave and elasticsearch work fine, but in order to get the full text search working I need to encode the attachment as base64.
I have followed this tutorial (http://rny.io/rails/elasticsearch/2013/08/05/full-text-search-for-attachments-with-rails-and-elasticsearch.html) but I assume there has been some changes to either Rails or Carrierwave as I can't get it to work. Specifically, when I am trying to encode the attachment as base64, I get the following Type error:
no implicit conversion of CarrierWave::SanitizedFile into String
The error is in the following line of the model:
File.open(Base64.encode64(File.read(document.file)))
If I replace the path with a url to an actual file it works fine.
I have searched SO and the only relevant answer I can find gives me the same error: Carrierwave encode file to base64 as process
I am a complete rails newbie and hopefully this is something that's obvious to everyone except me, but we're all beginners at first, right?
Thanks!
CarrierWave's read method returns the content of the file. So assuming Document is your model and file is your uploader attribute, this should work:
Base64.encode64(document.file.read)
I gonna upload files to rackspace(video, audio and images) in rails with paperclip or carrierwave, I need to Know the kind of file, to show in the view with image_tag, or video_tag or audio_tag, rackspace tell me the kind of file? or I have to store in my database? thanks
You can query/set the file type by using the 'content_type' function located in the 'ruby-cloudfiles' library.
See here: https://github.com/rackerlabs/ruby-cloudfiles/blob/master/lib/cloudfiles/storage_object.rb#L80-L82
Something like this should work for creating the object:
container = conn.create_container('new_container')
obj = container.create_object('new_obj.txt')
obj.load_from_filename('./obj.txt')
obj.content_type = 'text/plain'
And to retrieve the object:
obj = container.object('new_obj.txt')
puts obj.content_type # text/plain
Even if rackspace would tell you the file type, you don't want it to, since it would take so long to run roundtrips from your server to theirs.
My code examples below assume carrierwave, but I'm sure paperclip has similar options. Two options:
Interpret the file extension
Something like: File.extname(user.avatar), which you then have to interpret however you like.
Record & interpret the mime type.
The carrierwave readme explains how to get carrierwave to calculate it in the first place, and then you should probably store it to your database manually or using carrierwave-meta. Then user.avatar.content_type would be something like image/jpeg which you could easily interpret as a particular file type.
I have successfully returned a thumbnail() request (using the Dropbox SDK) in my rails app, but I don't understand how to process the response. I would like to show the thumbnail on a webpage.
I also tried to save the response to a tmp file, but get a UndefinedConversionError ("\xFF" from ASCII-8BIT to UTF-8) error.
I'm actually doing exactly what you are asking for. What I did was to convert the returned bytes into a base64 string. In C# it's quite easy as there is a convert function to do that.
On the webpage you then have to set the src attribute of a img tag to
<img src="data: image/jpg;base64,PlaceBase64StringHere"...../>
There is a little overhead in the converted string, but it's very easy to handle and you use the power of the client browser to render the image.
I'm building a website using Rails and I have a Model with some text type value store in MySQL database, I need to provide a download link for my users to download a "*.txt" file which contains those texts.
what I've tried is to use render :text => my_text but it's kind of ugly and the browser can't start a download .
Not I'm trying to use CarrierWave and mount a output_file to my model , I want to build a method to generate a file from its text value. Any suggestion would be greatly appreciated. Thanks!
send_data 'text to send', :filename => 'some.txt'
Documentation Here