lazy-schema 0.4.0

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Lazy Schema

Quick and simple schema validator.

Installation

pip install lazy-schema

How to Use

from lazy_schema import schema
from datetime import datetime
from bson import ObjectId

exampleSchema = schema(
    stringField="Hello World!",
    numberField=123,
    booleanField=True,
    lambdaField=lambda: datetime.utcnow(),
)

document = exampleSchema(
    stringField="Hi World!",
)

print(document)

{
    "stringField": "Hi World!",
    "numberField": 123,
    "booleanField": True,
    "lambdaField": [datetime Object]
}

Loading JSON Files

{
    "stringField": "Hi World!",
    "numberField": 123,
    "booleanField": true
}

from lazy_schema import schema

exampleSchema = schema(
    "path/to/file.json",
    lambdaField=lambda: datetime.utcnow(),
)

document = exampleSchema(
    stringField="Hi World!",
)

print(document)

{
    "stringField": "Hi World!",
    "numberField": 123,
    "booleanField": True,
    "lambdaField": [datetime Object]
}

SchemaPool

Just a collection where you can keep all your schemas.

from lazy_schema import SchemaPool

schemas = SchemaPool()

schemas.set(
    "my_schema",
    hello="world!",
    number=123,
)

schemas.set(
    "my_other_schema",
    hello="there!",
    number=456,
)

print(schemas.my_schema())
print(schemas.my_other_schema())

{
    "hello": "world!",
    "number": 123
}

{
    "hello": "there!",
    "number": 456
}

Loading from MongoDB with SchemaPool

You can load MongoDB documents with SchemaPool!

MongoDB Document

{
    "_id": [ObjectId],
    "__im_a_comment__": null,
    "hello": "world!",
    "number": 123
}

Script

from pymongo import MongoClient
from lazy_schema import SchemaPool

mongo = MongoClient(...)
collection = mongo.my_database.my_schemas

schemas = SchemaPool()

schema = schemas.pymongo(
    collection,
    query={
        "_id": ObjectId(...),
    },
)

print(schema())

Result

{
    // `_id` is always excluded.
    "hello": "world!",
    "number": 123
}

You can also add it into the SchemaPool.

...
schema.add_to("my_schema", schemas)

Special Keywords

Field names that are enclosed with double underscores _ are special keywords. They are not included in the schema.

These can be used when creating a schema,

exampleSchema = schema(
    __discrete__=True,
    ...
)

inside a schema validation,

document = exampleSchema(
    __discrete__=True,
    ...
)

and inside a JSON file.

{
    "__discrete__": true,
    ...
}

__discrete__

Excludes fields with a None default value.

from lazy_schema import schema

exampleSchema = schema(
    __discrete__=True,
    fieldA="Hello World!",
    fieldB=None,
    fieldC="Hi World!",
)

document = exampleSchema(
    fieldA=None,
)

print(document)

{
    "fieldA": None,
    "fieldC": "Hi World!"
}

__no_default__

Default values are not written.

from lazy_schema import schema

exampleSchema = schema(
    __no_default__=True,
    fieldA="Hello World!",
    fieldB=None,
    fieldC="Hi World!",
)

document = exampleSchema(
    fieldA="Hi There!",
)

print(document)

{
    "fieldA": "Hi There!"
}

__no_null__

None values will never be written.

from lazy_schema import schema

exampleSchema = schema(
    __no_null__=True,
    fieldA="Hello World!",
    fieldB=None,
    fieldC="Hi World!",
)

document = exampleSchema(
    fieldA=None,
)

print(document)

{
    "fieldC": "Hi World!"
}

Comments

Any field names enclosed with double underscores __name__ will never be written.

from lazy_schema import schema

exampleSchema = schema(
    __comment__="fieldA should not be None!",
    fieldA="Hello World!",
    __yet_another_comment__="fieldB is always None...",
    fieldB=None,
    __fieldC__="fieldC should always have 'World' in it!",
    fieldC="Hi World!",
)

document = exampleSchema(
    fieldA=None,
)

print(document)

{
    "fieldA": "Hello World!",
    "fieldB": None,
    "fieldC": "Hi World!"
}