This module provides validation for String / Text values

The following validators are available:

• validate_has_prefix/3 which will check if a given field is prefixed by some given fixed or dynamic string

Example:

# Simple prefix
iex> types = %{token: :string}
iex> params = %{token: "private|some-random-string-id"}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: "private")
#Ecto.Changeset<action: nil, changes: %{token: "private|some-random-string-id"}, errors: [], data: %{}, valid?: true>

# Prefix with separator
iex> types = %{token: :string}
iex> params = %{token: "private|some-random-string-id"}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: "private", separator: "|")
#Ecto.Changeset<action: nil, changes: %{token: "private|some-random-string-id"}, errors: [], data: %{}, valid?: true>

# Wrong prefix
iex> types = %{token: :string}
iex> params = %{token: "private|some-random-string-id"}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: "provider")
#Ecto.Changeset<action: nil, changes: %{token: "private|some-random-string-id"}, errors: [token: {"is not prefixed by %{prefix}.", [validation: :has_prefix]}], data: %{}, valid?: false>

# Correct prefix but wrong separator
iex> types = %{token: :string}
iex> params = %{token: "private|some-random-string-id"}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: "private", separator: "_")
#Ecto.Changeset<action: nil, changes: %{token: "private|some-random-string-id"}, errors: [token: {"is not prefixed by %{prefix}.", [validation: :has_prefix]}], data: %{}, valid?: false>

# Dynamic prefix from function which is correct
iex> types = %{token: :string}
iex> params = %{token: "private|some-random-string-id"}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: fn _chgst, _opts -> "private" end)
#Ecto.Changeset<action: nil, changes: %{token: "private|some-random-string-id"}, errors: [], data: %{}, valid?: true>

# Dynamic prefix from another changeset field
iex> types = %{token: :string, provider: :string}
iex> params = %{token: "iamsvc|some-random-string-id", provider: "iamsvc"}
iex> changeset = Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: fn chgst, _opts -> Ecto.Changeset.get_field(chgst, :provider) end)
iex> changeset.changes.provider
"iamsvc"
iex> changeset.changes.token
"iamsvc|some-random-string-id"
iex> changeset.valid?
true

# Dynamic prefix from another changeset field
iex> types = %{token: :string, provider: :string}
iex> params = %{token: "some-random-string-id", provider: nil}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: fn chgst, _opts -> Ecto.Changeset.get_field(chgst, :provider) end)
#Ecto.Changeset<action: nil, changes: %{token: "some-random-string-id"}, errors: [], data: %{}, valid?: true>

# Dynamic prefix from function, which fails
iex> types = %{token: :string}
iex> params = %{token: "private|some-random-string-id"}
iex> Ecto.Changeset.cast({%{}, types}, params, Map.keys(types))
...> |> validate_has_prefix(:token, prefix: fn _chgst, _opts -> "test" end)
#Ecto.Changeset<action: nil, changes: %{token: "private|some-random-string-id"}, errors: [token: {"is not prefixed by %{prefix}.", [validation: :has_prefix]}], data: %{}, valid?: false>