![]() Your S3 credentials can be found on the Your Security Credentials section of the AWS console.Īll files in S3 are stored in buckets which act basically likeĭirectories. The access key identifies your S3 account and the secret access key should be treated like a password. The free tier offers sufficient storage space for learning purposes.Īccess to S3 is governed by a set of credentials: an access key id and a secret access key. Let’s set that up… Create an AWS Account and an S3 Bucketįirst you’ll need to create and activate an Amazon Web Services account if you don’t already have one. Then when the application runs, it will decrypt that encrypted file and use our credentials to communicate with Amazon S3. To avoid that, we need Rails to encrypt our Amazon S3 credentials in a special file that gets deployed with the application. Here’s the rub: those credentials are super-secret! If they were revealed, someone could hijack our account and run up our storage bill. All of the cloud-based storage services supported by Active Storage require a set of credentials. We’re almost ready to turn our attention to uploading files to a cloud-based storage service when running in the production environment, but first a bit of setup is needed. It’s not installed by default, so we need to uncomment the following line in the Gemfile: To generate variants for images, Rails uses the image_processing gem. For example, an original image might be 300x300 pixels and have a thumbnail variant that’s only 150x150 pixels. It’s a variation of the original uploaded image. Active Storage has an answer for that: it can create something it calls a variant. For example, you might want to resize an uploaded image to generate a smaller thumbnail image. But sometimes you need to transform those image. Create Image VariantsĪctive Storage will always store unaltered copies of uploaded files. As an alternative to writing custom validations for image uploads, check out the Active Storage Validations gem which includes a variety of common validations you might want to perform. You’ll want to think carefully about what types of files can be uploaded to your app, and what size you’re willing to handle. If the content_type isn’t one of our acceptable types, then we add a validation error to the main_image attribute with the message "must be a JPEG or PNG".Ĭonsider those validations as bare minimums. add ( :main_image, "must be a JPEG or PNG" ) end end ![]() add ( :main_image, "is too big" ) end acceptable_types = unless acceptable_types. To do that, we add a declaration in the appropriate model like so:ĭef acceptable_image return unless main_image. ![]() Suppose, for example, we want our Event model to have one attached image-the main image for the event. ![]() The database is now ready to join any ActiveRecord model to a blob (an uploaded image), but we still need to declare associations in our models. So with these two pieces of information-a foreign key and a class name-the row knows exactly which record it’s referencing. Here’s the takeaway: The active_storage_attachments table joins any ActiveRecord model to its images (or attachments) because it’s a polymorphic join table. The second row in the active_storage_attachments table has a foreign key pointing to the user (because User is in the record_type column) and a foreign key pointing to the blob. It knows the record_id is a foreign key for an event, in this case, because the record_type column contains Event. Notice the first row in the active_storage_attachments table has a foreign key pointing to the event and another foreign key pointing to the blob. ![]() For example, here’s a polymorphic join table that joins an event to it’s uploaded image and a user to it’s uploaded image: But it wouldn’t know what type of record it’s pointing to! □īy adding the polymorphic: true option, the migration creates two columns: a column named record_id which contains a foreign key and a column named record_type which contains the name of an ActiveRecord model class. If the polymorphic: true option weren’t added here, then the migration would simply create a column named record_id which would contain a foreign key pointing to a record. This means that the record it’s referencing can be any ActiveRecord model. references :record, null: false, polymorphic: true, index: false ![]()
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