# PlugParamsValidation
Provides functionality for validating parameters
## Installation
```elixir
def deps do
[
{:plug_params_validation, "~> 0.1.0"}
]
end
```
## Usage
In your router:
```elixir
import ParamsValidation
```
in order to get easy access to `expect/1` function and `:params_validation` plug
Then, add the following plug. make sure it happens after the body parser plug:
```elixir
plug :params_validation
```
Now, every endpoint with `expect/1` will validate what ever you specify in `expect`
example:
```elixir
post "/register", expect(body_params: %{first_name: :string, last_name: :string, age: :integer}) do
first_name = conn.body_params.first_name
last_name = conn.body_params.last_name
age = conn.body_params.num
...
end
```
if you would like to specify optional fields, you can pass a list to the `:optional_body_params` parameter in `expect/1`
optionals will be defaulted to nil.
example:
```elixir
post "/register", expect(body_params: %{first_name: :string, last_name: :string, age: :integer, phone: :string},
optional_body_params: [:phone]) do
first_name = conn.body_params.first_name
last_name = conn.body_params.last_name
age = conn.body_params.num
phone = conn.body_params.phone || Phone.default_value
...
end
```
this also works for `GET` requests:
example:
```elixir
get "/register/:name", expect(path_params: %{name: :string}) do
# name can be used and trusted to be a string
...
end
```
You can mix between `body_params` `optional_body_params` and `path_params` inside `POST`, `PUT`...
When a request with bad parameters happens, the plug response with
status code 400 and the following body:
```json
{
"errors": {
"last_name": [
"can't be blank"
],
"age": [
"can't be blank"
]
}
}
```