Ensure a value is present.

Vex uses the Vex.Blank protocol to determine "presence." Notably, empty strings and collections are not considered present.

Options

• :message: Optional. A custom error message. May be in EEx format and use the fields described in "Custom Error Messages," below.

Examples

iex> Vex.Validators.Presence.validate(1, true)
:ok
iex> Vex.Validators.Presence.validate(nil, true)
{:error, "must be present"}
iex> Vex.Validators.Presence.validate(false, true)
{:error, "must be present"}
iex> Vex.Validators.Presence.validate("", true)
{:error, "must be present"}
iex> Vex.Validators.Presence.validate([], true)
{:error, "must be present"}
iex> Vex.Validators.Presence.validate([], true)
{:error, "must be present"}
iex> Vex.Validators.Presence.validate([1], true)
:ok
iex> Vex.Validators.Presence.validate({1}, true)
:ok

Custom Error Messages

Custom error messages (in EEx format), provided as :message, can use the following values:

iex> Vex.Validators.Presence.__validator__(:message_fields)
[value: "The bad value"]

An example:

iex> Vex.Validators.Presence.validate([], message: "needs to be more sizable than <%= inspect value %>")
{:error, "needs to be more sizable than []"}