tranquilizer 0.3.0

Put your functions to REST

# Tranquilizer

Deploy a REST API with one line by decorating your functions.

## Install

The package is available for all Mac, Linux, and Windows on my conda channel. Python 2 is not supported.

```
> conda install -c defusco tranquilizer
```

## Quick start

In a script file called `cheese_shop.py` the decorated function
will be served as an end point called `cheese` with the GET method. The
function must return a JSON serializable object. Dictionaries are preferable.

See the [complete description of `@tranquilize()`](#tranquilize-decorator) below.

```python
from tranquilizer import tranquilize

@tranquilize()
def order(cheese):
'''I'd like to buy some cheese!'''
return {'response':"I'm afraid we're fresh out of {}, Sir.".format(cheese)}
```

The REST API is served by [Flask](http://flask.pocoo.org/) and [Flask-RESTPlus](http://flask-restplus.readthedocs.io/en/stable/index.html)
using the `tranquilizer` command.


```
> tranquilizer cheese_shop.py
* Serving Flask app "tranquilizer.application" (lazy loading)
* Environment: production
WARNING: Do not use the development server in a production environment.
Use a production WSGI server instead.
* Debug mode: off
* Running on http://0.0.0.0:8086/ (Press CTRL+C to quit)

```

Let's see if there is any Red Leicester.

```
> curl -G http://localhost:8086/order --data-urlencode "cheese=Red Leicester"
{"response":"I'm afraid we're fresh out of Red Leicester, Sir."}
```

How about in Python?

```python
In [1]: import requests

In [2]: response = requests.get('http://localhost:8086/order', params={'cheese':'Red Leicester'})

In [3]: response.json()
Out[3]: {'response': "I'm afraid we're fresh out of Red Leicester, Sir."}
```

The *tranquilized* API is documented with [Swagger](https://swagger.io/tools/open-source/) and is accessible
in your web browser at [http://localhost:8086](http://localhost:8086).


## Tranquilize Decorator

The `@tranqulize` decorator will assign the GET method by default. POST is also supported with `method='post'`.
Other methods are under consideration.

By default a *tranquilized* function will receive all inputs as strings. This behavior can be modified by using [type hints](https://docs.python.org/3/library/typing.html). When data is received by the Flask server it will use the provided
type function to transform the string to the requested data type. This avoids having to perform the conversion in your *tranquilized* function.

## Supported source formats

Tranquilizer can serve functions written in Python source (`.py`) files or Jupyter Notebooks (`.ipynb`).

When working interactively in Jupyter Notebooks the decorated functions will continue to operate as normal.
Note that all calls to [Jupyter Magic](https://ipython.readthedocs.io/en/stable/interactive/magics.html)
and Shell (`!`) commands will be ignored when the REST API is served.
Only those lines will be ignored, the rest of the cell will continue to run.

## Data Types

In addition to [*builtin* types](https://docs.python.org/3/library/stdtypes.html) Tranquilizer
provides specialized support for Lists, date/datetime, and files.


|Type|Description|
|----|-----------|
|`datetime.date` or `datetime.datetime`| Converts string with `dateutil.parser.parse` and returns specified type.|
|`list`| Converts *repeated* arguments to a list of strings.|
|`typing.List[<type>]`| Converts *repeated* arguments to a list; each value is converted to `<type>`.|

`List` arguments are constructed using the `action='append'` argument described in
the [Flask RESTPlus documentation](http://flask-restplus.readthedocs.io/en/stable/parsing.html#multiple-values-lists).
Any valid type can be used in `List[]`.

The following file-like types are handled by [werkzeug `FileStorage`](http://werkzeug.pocoo.org/docs/0.14/datastructures/#werkzeug.datastructures.FileStorage).
`FileStorage` is a file-like object that supports methods like `.read()` and `.readlines()`.
These types support sending files with cURL using `-F`.

|Type|Description|
|----|-----------|
|`typing.BinaryIO`| File-like object to read binary data.|
|`typing.TextIO`| Converts `FileStorage` type to `io.StringIO()`.|

Further, specific support for Image and NumPy files are provided. The binary contents of the file are automatically converted.

|Type|Description|
|----|-----------|
|`PIL.Image.Image`| Converts `FileStorage` type to PIL Image.|
|`numpy.ndarray`| Converts `FileStorage` type to NumPy array using `np.load()`. |

### Custom types

Custom type classes can be built...

## Type hints example

The example below uses `int`, `datetime.datetime`, and `typing.List`. `datetime.datetime` support
has been built with `datetutil` and will convert any compatible datetime string to a `datetime.datetime` object. `typing.List`
supports specialization with `[]` and will transform all *repeated* arguments passed to the REST API into a list and convert
the type of each element.

Finally, tranquilizer supports default arguments.

```python
from tranquilizer import tranquilize
from datetime import date
from typing import List

@tranquilize(method='post')
def convert(string: str, date: date, items: List[float], factor: int = 10):
'''Let's convert strings to something useful'''

new_items = [i * factor for i in items]

response = {
'string': string.upper(),
'date' : date.strftime('%c'),
'items' : new_items
}

return response
```

Let's see what happens when I POST to this REST API.

```python
In [1]: data = {'string':'hello, world!', 'date':'4th July 1776', 'items':range(5)}

In [2]: import requests

In [3]: response = requests.post('http://localhost:8086/convert', data=data)

In [4]: response.json()
Out[4]:
{'date': 'Thu Jul 4 00:00:00 1776',
'items': [0.0, 10.0, 20.0, 30.0, 40.0],
'string': 'HELLO, WORLD!'}

In [5]:
```