Data validation in Elixir
The package can be installed by adding litmus to your list of dependencies in
mix.exs:
def deps do
[
{:litmus, "~> 1.0.2"}
]
endLitmus validates data against a predefined schema with the Litmus.validate/2
function.
If the data is valid, the function returns {:ok, data}. The data returned
will be coerced according to the provided schema.
If the data passed does not follow the rules defined in the schema, the
function returns {:error, error_message}. It will also return an error when
receiving a field that has not been specified in the provided schema.
schema = %{
"id" => %Litmus.Type.Any{
required: true
},
"username" => %Litmus.Type.String{
min_length: 6,
required: true
},
"pin" => %Litmus.Type.Number{
min: 1000,
max: 9999,
required: true
},
"new_user" => %Litmus.Type.Boolean{
truthy: ["1"],
falsy: ["0"]
},
"account_ids" => %Litmus.Type.List{
max_length: 3,
type: :number
},
"remember_me" => %Litmus.Type.Boolean{
default: false
}
}
params = %{
"id" => 1,
"username" => "user@123",
"pin" => 1234,
"new_user" => "1",
"account_ids" => [1, 3, 9]
}
Litmus.validate(params, schema)
# => {:ok,
# %{
# "id" => 1,
# "new_user" => true,
# "pin" => 1234,
# "username" => "user@123",
# "account_ids" => [1, 3, 9],
# "remember_me" => false
# }
# }
Litmus.validate(%{}, schema)
# => {:error, "id is required"}Litmus currently supports the following types.
Litmus.Type.AnyLitmus.Type.BooleanLitmus.Type.DateTimeLitmus.Type.ListLitmus.Type.NumberLitmus.Type.String
Litmus comes with a Plug for easy integration with Plug's built-in router. You can automatically validate query
parameters and body parameters by passing the litmus_query and litmus_body private options to each route. When
declaring the plug you must include a on_error/2 function to be called when validation fails. It is recommended that
you initialize this Plug between the :match and :dispatch plugs. If you want processing to stop on a validation
error, be sure to halt the request with Plug.Conn.halt/1.
defmodule MyRouter do
use Plug.Router
plug(Plug.Parsers, parsers: [:urlencoded, :multipart])
plug(:match)
plug(Litmus.Plug, on_error: &__MODULE__.on_error/2)
plug(:dispatch)
@schema %{
"id" => %Litmus.Type.Number{
required: true
}
}
get "/test", private: %{litmus_query: @schema} do
Plug.Conn.send_resp(conn, 200, "items")
end
post "/test", private: %{litmus_body: @schema} do
Plug.Conn.send_resp(conn, 200, "items")
end
def on_error(conn, error_message) do
conn
|> Plug.Conn.send_resp(400, error_message)
|> Plug.Conn.halt()
end
end
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