Can i use this in a Rails application? Yes, you can use it in a rails application. The file not being written properly is probably because I forgot to open the destination in write-binary mode. I'll edit that now. This reads the whole file in memory. The best way is IO. Show 3 more comments. Abram Clemens Helm Clemens Helm 3, 1 1 gold badge 19 19 silver badges 13 13 bronze badges. And more efficient as the output is not stored as a string in memory.
Though it's actually useful having both answers displayed, so people like me can see both, think about the differences and then choose this answer consciously for the right reasons : — Maxwell Evans. I'm getting a security warning from Rubocop when using open. I replaced it with URI. Read more about that cop here: rubydoc. By default, files created with Tempfile. This can pose problems for applications or tools like Carrierwave and soffice that rely on a file's extension to perform their operations.
In these cases, you can pass an extension to the Tempfile initialization as demonstrated above in Anatomy of Tempfile new. If you need to dynamically determine your file's extension, you can usually grab it from the URL or file path you are reading into your Tempfile:. Many developers use local file storage for their development environment. In these cases, local file paths often appear in methods that are expecting URLs.
Not fun. We like Ruby Tempfiles for performing file-oriented operations on remote resources. What do you use? You may unsubscribe at any time using the unsubscribe link in the digest email. See our privacy policy for more information. Have you ever needed to download and save an image in your Ruby application?
Read on to find out how. The most popular way to download a file without any dependencies is to use the standard library open-uri. Kernel open is a method that you can use to open files, streams, or processes to read to or write from. For example, you can open a file and read its contents with the following code:.
We can use this to download an image and then save it as a file. To do so, we first require open-uri then use the open method to access an image URL. We can then open up a file and write the contents of the image to the file. Open up IRB and try the following:. Suggest changing that part to Tempfile then io. Show 2 more comments.
More complex cases are shown further down in the same document. Arkku Arkku Here's the link specifically: ruby-doc. Add a comment. Felix 3, 2 2 gold badges 26 26 silver badges 41 41 bronze badges. KrauseFx KrauseFx 11k 6 6 gold badges 44 44 silver badges 52 52 bronze badges. This reads the whole file into memory before writing it to disk, so That said, if you're OK with that, a shorter version assuming url and filename are in variables url and file , respectively , using open-uri as in the first: File.
Dead simple, for the trivial download case. Expanding on Dejw's answer edit2 : File. Sorry, but I don't know a more elegant way of having Ruby wait for the buffer to fill. Edit: This is a version that automatically adjusts itself to keep the buffer just at or below capacity.
Isa Isa 1 1 silver badge 3 3 bronze badges. Rolf Rolf 39 1 1 bronze badge. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. This is a success, but this was a straightforward example. In practice you would want to handle potential errors, such as a error for a missing image.
The thing is, using open-uri like this is not ideal. First up, the above code is not very memory efficient, it loads the entire image into memory and then writes to disk. It also turns out that open-uri has some other quirks. Notably, open-uri:. To solve all of this, Janko created the Down gem. It allows you to avoid these issues to safely and efficiently download files.
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