Rails file_field size restrictions

Question

I currently have the below for uploading images, but I also want to add a restriction that prevents users from uploading any file less than 50px in height. Is this possible?

file_field "form", "image", accept: 'image/png,image/gif,image/jpeg'

Answer 1

Is this possible?

Yes it's possible, but you need some javascript to do it on the client side, here is am example. Change that html input to the rails helper.

html

<input id="image" name="img" type="file" />
/*  */
<img src="#" alt="This image is going to load" id="image_on_load" />
<p id='image_info_width'>    </p>
<p id='image_info_heigth'>    </p>

the js code:

// The upload listner function
$('#image').on('change', function() {
  var img = document.getElementById('image_on_load');
  var reader = new FileReader();
  // add uploaded image to the img element
  reader.onloadend = function() {
    $('#image_on_load').prop('src', reader.result)
  }
  reader.readAsDataURL(this.files[0]);
  // listen onload event and get dimension
  img.onload = function(image) {

    $('#image_info_width').text('Width: ' + image.target.width)
    $('#image_info_heigth').text('Height: ' + image.target.height)
    // here you able to upload or reject
    // file accourding to dimension
  }
});

In this example image was uploaded and the you able to get the width and the height.

JSFIDDLE

Read how the works with JS in Rails 7 Must-Reads about JavaScript with Ruby on Rails

Answer 2

Try this one, Maybe this will help you: Reference

validate :validate_image_size

def validate_image_size
  image = MiniMagick::Image.open(picture.path)
  unless image[:height] < 50
    errors.add :image, "should be 50px minimum!" 
  end
end

This will work for you if you use MiniMagick.