file upload field empty when validation error

rubyonrails-talk
1

Hiya

In my view, I'm using <%= f.file_field :file %>

Problems is, if the form has a validation error, this field is cleared - and the user has to reselect a file

Does anyone have a solution for this?

thanks Jason

2

Does anyone have any ideas?

Is it even possible to fix?

Have been googling, but no luck

3

jasonb wrote:

In my view, I'm using <%= f.file_field :file %>

Problems is, if the form has a validation error, this field is cleared - and the user has to reselect a file

Does anyone have a solution for this?

HTML file select controls are always initially blank in Rails, and this is also enforced by most browsers. This is because a malicious web page could get you to upload an arbitrary file by hiding the select from the user.

4

Ok but this is after the form his submitted and returned with errors

Can anyone advise of a way to get around this?

I'm not sure of the nature of the object returned by file_field.... does it contain the file path? am I able to re-populate the file field based on that object?

5

Maybe I could ask this....

When a form is submitted with file_field.... what is the object that is generated from the file_field?..... and what is the best way to inspect that object?

For example, if I wanted to output that object with the validation- errors, for the sake of debugging, how would I do it?

6

Maybe I could ask this....

When a form is submitted with file_field.... what is the object that is generated from the file_field?..... and what is the best way to inspect that object?

This is how I do it (which I didn't come up with all my myself) in a create action of a controller:

     data = params[:model].delete('data') # HashWithIndifferentAccess still needs the actual key type to .delete

     params[:dump] = "data=#{data}; filename=#{data.original_filename}; content_type=#{data.content_type}"

     if data.blank?        flash[:error] = "No image file selected for upload"        redirect_to :action => 'new' and return      end      content = data.read      if content.blank?        flash[:error] = "Selected upload file was empty"        redirect_to :action => 'new' and return      end

In my case the file is intended to be an image. I think that 'data' will be either a StringIO or File object.

That might give you enough to experiment with.

For example, if I wanted to output that object with the validation- errors, for the sake of debugging, how would I do it?

That's what I was doing with params[:dump]. In the view (layout?), I have a <%= debug(params) %> to see what's going on.

-Rob

Ok but this is after the form his submitted and returned with errors

Can anyone advise of a way to get around this?

I'm not sure of the nature of the object returned by file_field.... does it contain the file path? am I able to re-populate the file field based on that object?

jasonb wrote:

In my view, I'm using <%= f.file_field :file %>

Problems is, if the form has a validation error, this field is cleared - and the user has to reselect a file

Does anyone have a solution for this?

HTML file select controls are always initially blank in Rails, and this is also enforced by most browsers. This is because a malicious web page could get you to upload an arbitrary file by hiding the select from the user.

-- We develop, watch us RoR, in numbers too big to ignore.

Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com

7

Thanks Rob, much appreciated