Starting with Paperclip version 4.0, all attachments are required to include a content_type validation, a file_name validation, or to explicitly state that they’re not going to have either.
Paperclip raises Paperclip::Errors::MissingRequiredValidatorError error if you do not do any of this.
In your case, you can add any of the following line to your Post model, after specifying has_attached_file :image
Option 1: Validate content type
validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
-OR- another way
validates_attachment :image, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }
-OR- yet another way
is to use regex for validating content type.
For example: To validate all image formats, regex expression can be specified as shown in
@LucasCaton’s answer
Option 2: Validate filename
validates_attachment_file_name :image, :matches => [/png\Z/, /jpe?g\Z/, /gif\Z/]
Option 3: Do not validate
If for some crazy reason (can be valid but I cannot think of one right now), you do not wish to add any content_type validation and allow people to spoof Content-Types and receive data you weren’t expecting onto your server then add the following:
do_not_validate_attachment_file_type :image
Note:
Specify the MIME types as per your requirement within content_type/ matches options above. I have just given a few image MIME types for you to start with.
Reference:
Refer to Paperclip: Security Validations, if you still need to verify. 🙂
You might also have to deal with the spoofing validation explained here https://stackoverflow.com/a/23846121