One does not simply delete an Arc attachment

[jerodsanto]

Let's say I want to delete an image attachment, but not replace it with a new one. I can't seem to figure out how to get that done.

I tried replacing the file field with a hidden field of same name and nil value or "" value:

<%= hidden_input f, :logo_image, value: "" %>

But that gives me:

no function clause matching in Arc.Actions.Store.store/2

When calling cast_attachments. I know there is an Arc.Actions.Delete, but I don't know how to invoke it.

If you lend me a hand I'd be happy to update the README to include this procedure.

Thanks in advance. 🍻

[brayhoward]

@jerodsanto I fugured out a way to delete the image going by the documentation for delete in the Arc README

Assuming you have already stored and uploaded an avatar to this user deleting it will look something like this.

# With a scope:
user = Repo.get! User, 1
path = YourApp.Avatar.url({user.avatar, user})

Avatar.delete({path, user})

The problem is that it only deletes the the image from wherever your storing it at, ex: S3, but doesn't remove the path url that is associated to the model.
so calling YourApp.Avatar.url({user.avatar, user}) returns a broken url which isn't worth a fuck really.

If I figure out how to get the correct behavior I'll post an update here.

[stavro]

There is no convenience yet for deleting objects through Ecto / arc_ecto. I will consider adding this.

However, to delete for now, the best option is likely to:

1. Update the user to remove the reference to the avatar (do this first, so all new image urls will result in nil or the default url. You never want to show a url to a removed object, which can happen if you don't do this first.
2. After the record is nillified, remove it from the file storage (this can even be done async, as it will be a slower operation).

user = Repo.get!(User, 1) # Assume there is a property :avatar on User

user
|> User.changeset(%{avatar: nil})
|> Repo.update!()

:ok = Avatar.delete({user.avatar, user})

# Since the above deletion doesn't really need to happen synchronously, you can delete it asynchronously to speed up the request/response.
# spawn(fn -> Avatar.delete({user.avatar, user}) end)

[brayhoward]

Thank you @stavro.
This is much better than what I was trying to implement!

[brayhoward]

This is pretty straight forward. I think updating the readme will be sufficient. I'll do that tomorrow and submit a PR. Thanks again.

[brayhoward]

When calling User.changeset(user, %{avatar: nil})

It's raising this error:
(FunctionClauseError) no function clause matching in Arc.Actions.Store.store/2

Any thoughts on what to do next?

[stavro]

Ah - if you currently send nil through cast_attachments it will fail.

Ok - for now send it through cast or use change directly:

Ecto.Changeset.change(user, %{avatar: nil})

rather than sending through cast_attachments. I'll get this fixed shortly.

[mamantoha]

When I try to delete attachment from iex -S mix nothing happens:

attachment = Repo.get Attachment, 1
path = Rumbl.Image.url({attachment.file, attachment})
Rumbl.Image.delete({path, attachment})

It returns :ok but the file still exists on the hard drive.

[bchase]

@mamantoha I was running into the same issue, but got things working with:

attachment = Repo.get Attachment, 1
path = Rumbl.Image.url({attachment.file, attachment})
[path | _] = String.split path, "?" # strips the "?v=1234" from the URL string
Rumbl.Image.delete({path, attachment})

Or perhaps more idiomatically:

attachment = Repo.get Attachment, 1
path =
  Rumbl.Image.url({attachment.file, attachment})
  |> String.split("?")
  |> List.first 
Rumbl.Image.delete({path, attachment})

Apparently the return from Image.url/1 needs to be trimmed as follows to make it usable by Image.delete/1:

"/foo/bar?v=1234"
"/foo/bar"

Hope this helps!

[GBH]

Deleting seems to remove file(s), but not directory it was in.

[jgonera]

Are there any plans to add an easier / more automatic way of removing files? Ideally I would like to just set the property for my attachment to nil and have arc_ecto take care of removing the file.