databind.tagline 0.1.3

De/serialize strings of comma-separated key-value pairs using Python type hints.

databind.tagline

Databind is a library inspired by Jackson-databind to describe and bind data models for object-oriented programming. The databind.tagline module provides functionality to (de-) serialize strings of comma-separated key-value pairs.

Syntax

• An object is defined of a comma-separated sequence of key-value pairs
• An array is defined as a sequence of values
• Key-value pairs or values can be grouped/nested with surrounding braces
• Unions can be instantiated by prefixing a brace with the union member name

Notation	Syntax	JSON representation
Object	a=b,c=d	{"a": "b", "c": "d"}
Array	a,b,c	["a", "b", "c"]
Union	a{b=c}	{"type": "a", "a": {"b": "c"}}
Nesting	a={b=c}	{"a": {"b": "c"}}
Nesting	a,{b=c},d	["a", {"b": "c"}, "d"]

Quickstart

from databind.core import datamodel, field, uniontype
from databind.tagline import from_str

@datamodel
class BindMount:
  src: str
  dst: str
  read_only: bool = field(altname='readonly', default=False)

@uniontype({
  'bind': BindMount
} flat=False)
class Mount:
  pass

assert from_str(Mount, 'bind{src=data/,dst=/opt/data}') == BindMount('data/', '/opt/data')
assert from_str(Mount, 'type=bind,bind={src=data/,dst=/opt/data}') == BindMount('data/', '/opt/data')
assert from_str(BindMount, 'src=data/,dst=/opt/data,readonly=true') == BindMount('data/', '/opt/data')

Notes

• All values are loaded as strings. It is up to the user of the load() function to interpret the values as needed. The dump() function converts numbers to string for convenience.
• The union syntax is loaded into nested form, which requires that @uniontype() are configured with flat=False.
• The actual data binding is out-sourced with the databind.json module (using a custom registry initialized with non-strict JSON converters, see databind.tagline:registry).
• The loader/dumper does not currently support escaping control characters. Dumping a string that contains a control character (like { or ,) will result in output that cannot be parsed.

---

Copyright © 2020 Niklas Rosenstein