# Tarams
Phoenix request params validation library.
[](https://github.com/bluzky/tarams/actions) [](https://coveralls.io/github/bluzky/tarams?branch=master) [](https://hex.pm/packages/tarams) [](https://hexdocs.pm/tarams/)
**Warning: Tarams v1.0.0 APIs is not back compatible**
- [Tarams](#tarams)
- [Why Tarams](#why-tarams)
- [Installation](#installation)
- [Usage](#usage)
- [Define schema](#define-schema)
- [Default value](#default-value)
- [Custom cast function](#custom-cast-function)
- [1. Custom cast function accept value only](#1-custom-cast-fuction-accept-value-only)
- [2. Custom cast function accept value and current object](#2-custom-cast-function-accept-value-and-current-object)
- [3.Custom cast function accept tuple {M, f}](#3custom-cast-function-accept-tuple-m-f)
- [Nested schema](#nested-schema)
- [Transform data](#transform-data)
- [Field name alias](#field-name-alias)
- [Convert data](#convert-data)
- [Validation](#validation)
- [Contributors](#contributors)
## Why Tarams
- Reduce code boilerplate
- Shorter schema definition
- Default function which generate value each casting time
- Custom validation functions
- Custom parse functions
## Installation
[Available in Hex](https://hex.pm/tarams), the package can be installed
by adding `tarams` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:tarams, "~> 1.0.0"}
]
end
```
## Usage
**Process order**
> Cast data -> validate casted data -> transform data
```elixir
@index_params_schema %{
keyword: :string,
status: [type: :string, required: true],
group_id: [type: :integer, number: [greater_than: 0]],
name: [type: :string, from: :another_field]
}
def index(conn, params) do
with {:ok, better_params} <- Tarams.cast(params, @index_params_schema) do
# do anything with your params
else
{:error, errors} -> # return params error
end
end
```
## Define schema
Schema is just a map and it can be nested. Each field is defined as
`<field_name>: [<field_spec>, ...]`
Or short form
`<field_name>: <type>`
Field specs is a keyword list thay may include:
- `type` is required, `Tarams` support same data type as `Ecto`. I borrowed code from Ecto
- `default`: default value or default function
- `cast_func`: custom cast function
- `number, format, length, in, not_in, func, required, each` are available validations
- `from`: use value from another field
- `as`: alias key you will receive from `Tarams.cast` if casting is succeeded
### Default value
You can define a default value for a field if it's missing from the params.
```elixir
schema = %{
status: [type: :string, default: "pending"]
}
```
Or you can define a default value as a function. This function is evaluated when `Tarams.cast` gets invoked.
```elixir
schema = %{
date: [type: :utc_datetime, default: &Timex.now/0]
}
```
### Custom cast function
You can define your own casting function, `tarams` provide `cast_func` option.
Your `cast_func` must follows this spec
#### 1. Custom cast fuction accept value only
```elixir
fn(any) :: {:ok, any} | {:error, binary} | :error
```
```elixir
def my_array_parser(value) do
if is_binary(value) do
ids =
String.split(value, ",")
|> Enum.map(&String.to_integer(&1))
{:ok, ids}
else
{:error, "Invalid string"
end
end
schema = %{
user_id: [type: {:array, :integer}, cast_func: &my_array_parser/1]
}
Tarams.cast(%{user_id: "1,2,3"}, schema)
```
This is a demo parser function.
#### 2. Custom cast function accept value and current object
```elixir
data = %{
name: "tada",
bold: true
}
schema = %{
name: [type: :string, cast_func: fn value, data ->
{:ok, (if data.bold, do: String.upcase(value), else: value)}
end]
}
Tarams.cast(data, schema)
# > %{name: "TADA"}
```
#### 3.Custom cast function accept tuple {M, f}
Your cast function must accept 2 arguments
```elixir
defmodule MyModule do
def upcase(value, data) do
{:ok, (if data.bold, do: String.upcase(value), else: value)}
end
end
```
```elixir
data = %{
name: "tada",
bold: true
}
schema = %{
name: [type: :string, cast_func: {MyModule, :upcase}]
}
Tarams.cast(data, schema)
# > %{name: "TADA"}
```
### Nested schema
With `Tarams` you can parse and validate nested map and list easily
```elixir
@my_schema %{
status: :string,
pagination: %{
page: [type: :integer, number: [min: 1]],
size: [type: :integer, number: [min: 10, max: 100"]]
}
}
```
Or nested list schema
```elixir
@user_schema %{
name: :string,
email: [type: :string, required: true]
addresses: [type: {:array, %{
street: :string,
district: :string,
city: :string
}}]
}
```
## Validation
`Tarams` uses `Valdi` validation library. You can read more about [Valdi here](https://github.com/bluzky/valdi)
Basically it supports following validation
- validate inclusion/exclusion
- validate length for string and enumerable types
- validate number
- validate string format/pattern
- validate custom function
- validate required(not nil) or not
- validate each array item
```elixir
product_schema = %{
sku: [type: :string, required: true, length: [min: 6, max: 20]]
name: [type: :string, required: true],
quantity: [type: :integer, number: [min: 0]],
type: [type: :string, in: ~w(physical digital)],
expiration_date: [type: :naive_datetime, func: &my_validation_func/1],
# dynamic required
width: [type: :integer, required: fn value, data -> data.type == "physical" end],
# validate each array item
tags: [type: {:array, :string}, each: [length: [max: 50]]]
}
```
### Dynamic required
- Can accept function or `{module, function}` tuple
- Only support 2 arity function
```elixir
def require_email?(value, data), do: is_nil(email.phone)
....
%{
phone: :string
name: [type: :string, required: fn value, data -> true end],
email: [type: :string, required: {__MODULE__, :require_email?}]
}
```
### Validate array item
Support validate array item with `:each` option, `each` accept a list of validators
```elixir
%{
values: [type: {:array, :number}, each: [number: [min: 20, max: 50]]]
}
```
## Transform data
### Field name alias
You can set alias name for schema fields
```elixir
data = %{
name: "tada"
}
schema = %{
name: [type: :string, as: :full_name]
}
Tarams.cast(data, schema)
# > %{full_name: "tada"}
```
### Convert data
You can specify a function similar to `cast_func` to manipulate data after casted.
However data object passed to transform function is original data before casting.
```elixir
data = %{status: 10}
schema = %{
name: [type: :string, into: fn value -> {:ok, "name: #{value}}" end]
}
Tarams.cast(data, schema)
# > %{name: "name: tada"}
```
- Transform function can return tuple `{:ok, value}`, `{:error, message}` or value directly.
```elixir
schema = %{
value: [type: :integer, into: &to_string/1]
}
```
## Contributors
If you find a bug or want to improve something, please send a pull request. Thank you!
