What I'm trying to do is passing an empty string as the value of a field, and validating it to check if not nil. Problem is that validate_required raise error on both nil and blank values. How to make it accept blank values?
schema
schema "messages" do
field :user_id, :string
field :text, :string
timestamps()
end
changeset
def changeset(struct, params \\ %{}) do
struct
|> cast(params, [:text, :user_id])
|> validate_required([:text, :user_id])
end
The behavior of validate_required is unfortunately hardcoded to consider empty as well as whitespace only strings as missing. You can however write a simple function to do the validation:
def changeset(struct, params \\ %{}) do
struct
|> cast(params, [:text, :user_id])
|> validate_not_nil([:text, :user_id])
end
def validate_not_nil(changeset, fields) do
Enum.reduce(fields, changeset, fn field, changeset ->
if get_field(changeset, field) == nil do
add_error(changeset, field, "nil")
else
changeset
end
end)
end
The function goes over each field, adding error for every field which has a value nil.
field :my_field, :string, default: "" See also the docs on empty values in changesets.https://github.com/elixir-ecto/ecto/issues/1684
Even if that won't fix your problem, adding a default value to the definition will allow you to create a workaround that will completely avoid the null value, even if it is not what you intend.
