fix(#634): added a generate function to support SQL Numeric field

[nisemenov]

Description

• a function for generate random value for SQL NUMERIC type has been added;
• appropriate tests have been added.

I have decided to add a new separate function to work with only SQL NUMERIC type like this, because Pydantic Decimal Constraints works in a slightly different way.

Also this function does not allow to use a negative scale and a scale larger than the declared precision. This can be used only with the SQL standard requirements (the scale must be in the range 0 to precision). And generated values can be either positive or negative.

Closes

• Closes Bug: handle_constrained_decimal not enforcing SQL numeric type precision properly #634

[adhtruong]

Based on examples and docs linked, from Pydantic

class Foo(BaseModel):
precise: Decimal = Field(max_digits=5, decimal_places=2)

foo = Foo(precise=Decimal('123.45')

and Postgres docs

So the number 23.5141 has a precision of 6 and a scale of 4.

how do these differ? Is this for trailing zero handling?

Based on failing example from issue it looks like an issue in generating the values themselves. Would this fix or similar apply to decimal handling too?

[nisemenov]

...

how do these differ? Is this for trailing zero handling?

Based on failing example from issue it looks like an issue in generating the values themselves. Would this fix or similar apply to decimal handling too?

Hi @adhtruong and thanks for reviewing!
Yes, it was my mistake, sorry for that. I didn't fully figure this topic out.

The main thing I have done in last commits:

• added a default value for scale=0 in SQLA module, this field is different from Pydantic (because SQL docs say "NUMERIC(precision) selects a scale of 0.");
• added a constraint check via max_digits and decimal_places to get_value_or_none func.;
• changed handle_decimal_length func.;
• decimal_places can be equal to max_digits.

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/polyfactory-docs-preview/636