romenigld

How to validate an array of strings for the upload files in Phoenix LiveView

Hello Guys,
I was doing the course of the PraProg Phoenix LiveView Pro and I was trying to do a validation for the upload files.
For example If I try to put just the name of the desks and not put any file for upload, I would like to show the validation for upload a file.

I tried to add a validate_required for the photo_urls on the changeset:

 defmodule LiveViewStudio.Desks.Desk do
  use Ecto.Schema
  import Ecto.Changeset

  schema "desks" do
    field :name, :string
    field :photo_urls, {:array, :string}, default: []

    timestamps()
  end

  @doc false
  def changeset(desk, attrs) do
    desk
    |> cast(attrs, [:name, :photo_urls])
    |> validate_required([:name, :photo_urls])
  end
end

But if I put just the name for the desks, the photo_urls are not validated.
as you can see the log:

[debug] QUERY OK db=2.1ms queue=1.3ms idle=1529.6ms
INSERT INTO "desks" ("name","photo_urls","inserted_at","updated_at") VALUES ($1,$2,$3,$4) RETURNING "id" ["Testing", [], ~N[2021-04-19 17:20:41], ~N[2021-04-19 17:20:41]]

But on the application this values are not showed. It shows only the those which have photo_urls.
But If I try to list all Desks, like:
iex> Desks.list_desks()
The empty photo_urls are recorded:

  %LiveViewStudio.Desks.Desk{
    __meta__: #Ecto.Schema.Metadata<:loaded, "desks">,
    id: 17,
    inserted_at: ~N[2021-04-16 21:11:22],
    name: "Testing",
    photo_urls: [],
    updated_at: ~N[2021-04-16 21:11:22]
  },

How can I validate an empty array of strings for the :photo_urls?

26 comments

/phoenix #file-uploading #liveview #uploads

9 4584 26

2023-12-05 05:07:29 UTC

Marked As Solved

romenigld

When I arrived in home I was thinking in to inspect the values.
So I do this:

defmodule LiveViewStudio.Desks.Desk do
  use Ecto.Schema
  import Ecto.Changeset

  schema "desks" do
    field :name, :string
    field :photo_urls, {:array, :string}, default: []

    timestamps()
  end

  @doc false
  def changeset(desk, attrs) do
    desk
    |> cast(attrs, [:name, :photo_urls])
    |> validate_required([:name])
    |> validate_empty_photo_urls()
  end

  def validate_empty_photo_urls(changeset)  do
    photos = get_field(changeset, :photo_urls)

    IO.inspect(photos, label: "Photos")

    if Enum.empty?(photos) do
      changeset = add_error(changeset, :photo_urls, "must insert a photo!")
      IO.inspect(changeset, label: "changeset")
    else
      changeset
    end
  end
end

So in the log shows me this:

Photos: []
changeset: #Ecto.Changeset<
  action: nil,
  changes: %{name: "test"},
  errors: [photo_urls: {"must insert a photo!", []}],
  data: #LiveViewStudio.Desks.Desk<>,
  valid?: false

And I can see it was working the validations and it wasn’t inserted in the database when I click on the button Upload.
So I was seeking why not it was showed the error and the thing is not having the error_tag for the :photo-urls.

So I add the error_tag on the beginning of the drag-and-drop div:

  <div class="drop" phx-drop-target="<%= @uploads.photo.ref %>">
      <div>
        <%= error_tag f, :photo_urls %>
        <img src="/images/upload.svg">
        <div>
          <label for="<%= @uploads.photo.ref %>">
            <span>Upload a file</span>
            <%= live_file_input @uploads.photo, class: "sr-only" %>
          </label>
          <span>or drag and drop</span>
        </div>
        <p>
          <%= @uploads.photo.max_entries %> photos max,
          up to <%= trunc(@uploads.photo.max_file_size / 1_000_000) %> MB each
        </p>
      </div>
    </div>

And now it’s working!
Thank you for the help guys, it was very helpful!

Post #20

Also Liked

cenotaph

my apologies, different language mix up there! I have corrected my post

Post #6

romenigld

Yes I know in the course it doesn’t cast the :photo_urls.
But I was testing to put just the :name and no files for uploads.
And then I notice it was saving on the database, but they don’t are showing.
So I was trying to do a validate in the schema.
For now your help make more sense.
But it would be nice to do this on the schema.
I will review some books, I think I saw something which is possible creating a custom validation.
I just don’t know how to do it now.
thank you for reply @f0rest8!

Post #9

sfusato

It invokes the validator function to perform the validation only if a change for the given field exists and the change value is not nil. The function must return a list of errors (with an empty list meaning no errors).

when the value is nil, the validator function won’t even be called; I believe you defined :photo_urls as an array of strings with the default value being empty list;
you must return a list of errors, [photo_urls: "must insert a photo!"], in the error case
[] in the no error case

Post #11