pystyx

Python implementation of Styx ETL declarative TOML.

For more information about Styx, please see the definition here.

Quick Start

1. In your Python project, mkdir maps

2. touch functions.styx (TODD: Add init for this) and functions.py (if you want to write custom functions)

3. In functions.styx, add an array called functions, with the names of any functions you plan on using in your mappings:

   # functions.styx
   
   functions = ["to_upper_case"]

4. In functions.py implement your custom function. Ensure that your function takes the same number of arguments as your expected input_paths, or use *args. The

   # functions.py
   
   from pystyx.functions import styx_function
   
   @styx_function
   def to_upper_case(value):
      return value.upper()
      

5. Add any of your Styx Definitions to the maps/ directory. For example,

   from_type = "erp_address"
   to_type = "Address"
   
   [fields]
   
       [fields.address1]
       input_paths = ["addr1"]
   
       [fields.address2]
       input_paths = ["addr2"]
   
       [fields.city]
       input_paths= ["city"]
   
       [fields.state]
       input_paths = ["province"]
       function = "to_upper_case"
   
       [fields.zip]
       input_paths = ["postalCode"]
   

6. Initialize maps in your Python code:

   // blob.json
   {
      "addr1": "123 Street",
      "addr2": "Ste. 800",
      "city": "Dallas",
      "province": "tx",
      "postalCode": "75080",
   }

   # main.py
   import json
   import pathlib
   
   import pystyx
   
   # Ensure that your decorated functions are evaluated
   from functions import *  
   
   with pathlib.Path("blob.json").open() as json_file:
       blob = json.load(json_file)
       maps = pystyx.create_maps()  # Defaults to `/maps` and `functions.styx`
       mapper = maps.get("erp_address")  # 'from_type` from the Definition above
       mapped_obj = mapper(blob)
       print(mapped_obj)

   Prints:

    {
       "address1": "123 Street",
       "address2": "Ste. 800",
       "city": "Dallas",
       "state": "TX",  // Upper case now
       "zip": "75080"
    }

Styx Validation

pystyx.create_maps() parses (and thereby validates) the Styx files before loading them. I hope to extract this validation as a CLI tool (along with generating Styx structures).

Styx Implementation

I wanted this to be a good first example of a Styx implementation, so I believe it currently implements all features of the Styx standard. Parsing and validation I would like to extract into its own library eventually.

Feature	Implemented
Structures
- JSON objects	✔️
Validation/Parsing
- Full parsing	✔️
Preprocessing
- input_paths	✔️
- output_paths	✔️
- function	✔️
- or_else	✔️
- on_throw	✔️
Fields
- field header	✔️
- input_paths	✔️
- possible_paths	✔️
- const	✔️
- from_type	✔️
- or_else	✔️
- on_throw	✔️
- many	✔️
Postprocessing
- input_paths	✔️
- output_paths	✔️
- function	✔️
- or_else	✔️
- on_throw	✔️