sqlrules 1.0.1

Compile constrained Pydantic models into SQLAlchemy WHERE-rule dictionaries.

SQLRules

Compile Pydantic Field constraint metadata into SQLAlchemy WHERE expressions.

SQLRules reads constraints declared on a model (Field(ge=18), min_length, Literal, …) and turns them into SQLAlchemy boolean expressions. It depends on Pydantic v2 and SQLAlchemy 2.x, performs no database I/O, and needs a dialect plugin only for non-portable operators (regex, JSON, arrays, …).

SQLRules does THIS (constraint metadata → expressions):
  Field(ge=18)           →  column >= 18

It does NOT do this (instance values → predicates):
  UserFilter(age=25)     →  column == 25   # not what sqlrules.compile does

Not an ORM, validator, or query builder: constraint metadata → expressions, nothing else.

In 30 seconds:

pip install "sqlrules>=1,<2"

from typing import Annotated

from pydantic import BaseModel, Field
from sqlalchemy import Column, Integer, MetaData, String, Table

import sqlrules

users = Table(
    "users",
    MetaData(),
    Column("age", Integer),
    Column("name", String),
)

class UserFilter(BaseModel):
    age: Annotated[int, Field(ge=18, le=65)]
    name: Annotated[str, Field(min_length=2)]

rules = sqlrules.compile(UserFilter, users)
# {
#     "age": [users.c.age >= 18, users.c.age <= 65],
#     "name": [length(users.c.name) >= 2],
# }

stmt = users.select().where(*sqlrules.where(rules))

pattern needs a plugin. Core compiles comparisons, lengths, Literal, and Enum. Regex / JSON / arrays require a dialect package (see below). Prefer static patterns; untrusted regex can be expensive (see SECURITY).

Full walkthrough: Getting started · Runnable scripts: examples/.

Latest	sqlrules on PyPI · Changelog
Docs	sqlrules.readthedocs.io
Python	3.10+ (Pydantic v2, SQLAlchemy 2.x)

---

Choose your path

Path	Start here
Not sure?	Start here
Compile constraints	Getting started
Dialect plugins	Plugin system
Evaluate fit	Design philosophy
Contribute	Contributing

---

Install

Requires Python 3.10+, Pydantic v2, and SQLAlchemy 2.x (pulled in transitively).

From PyPI

pip install "sqlrules>=1,<2"
# or: uv add "sqlrules>=1,<2"

Optional dialect plugins (same major line as core):

pip install "sqlrules-postgresql>=1,<2"   # ~ / ~*, JSONB, ARRAY, range
pip install "sqlrules-sqlite>=1,<2"       # REGEXP helper + JSON
pip install "sqlrules-mysql>=1,<2"        # REGEXP, JSON, full-text
pip install "sqlrules-mssql>=1,<2"        # JSON + LEN string ops

Extras are equivalent shortcuts (pull the matching plugin package):

pip install "sqlrules[postgresql]"
pip install "sqlrules[dialects]"   # all four

SQLite pattern emits REGEXP — call sqlrules_sqlite.register_regexp(connection) on each connection before executing queries.

From source (contributors)

git clone https://github.com/eddiethedean/sqlrules.git
cd sqlrules
python -m venv .venv && source .venv/bin/activate
make install   # editable core + all four dialect plugins

End users should install from PyPI. You do not need to clone this repo or install from packages/ for normal application use.

Plugin example

from typing import Annotated, Any

from pydantic import BaseModel, Field
from sqlalchemy import Column, MetaData, String, Table
from sqlalchemy.dialects.postgresql import JSONB

import sqlrules
from sqlrules import Compiler, JsonContains
from sqlrules_postgresql import PostgresPlugin

table = Table(
    "rows",
    MetaData(),
    Column("name", String),
    Column("meta", JSONB),
)

class RowFilter(BaseModel):
    name: Annotated[str, Field(pattern=r"^A")]
    meta: Annotated[dict[str, Any], JsonContains({"active": True})]

# dialect= is a hint for custom translators only — it does not load plugins.
compiler = Compiler(plugins=[PostgresPlugin()], dialect="postgresql")
rules = compiler.compile(RowFilter, table)
stmt = table.select().where(*sqlrules.where(rules))

See examples/postgresql_pattern.py.

Common failures

Symptom	Fix
UnsupportedConstraintError on pattern	Install a dialect plugin and pass it to Compiler(plugins=[...])
NameError: sqlrules after from sqlrules import Compiler	Also import sqlrules (or import where)
SQLite REGEXP errors at execute time	Call register_regexp(connection)

More: Troubleshooting.

Supported constraints (1.0)

Constraint	SQLAlchemy expression
gt / ge / lt / le	column > / >= / < / <= value
multiple_of	column % value == 0
min_length / max_length	func.length(column) >= / <= value
Literal[...]	column.in_(...)
Enum	column.in_(...)

pattern is extracted into IR (PatternSpec) but has no portable core translator. Install a dialect plugin or register a custom translator.

With emit_type_checks=True, supported scalar annotations also emit type_check (TypeSpec) IR — likewise plugin-translated only.

Dialect markers (JsonContains, ArrayContains, RangeContains, FullTextMatch, …) are re-exported from sqlrules (and live in sqlrules.markers); they require a dialect plugin.

Unsupported constraints raise UnsupportedConstraintError by default. Use on_unsupported="warn" or "ignore" for unknown operators. Unconstrained fields with supported types are omitted from the rules dict. Fields with unsupported type annotations always raise — even if unconstrained.

When not to use SQLRules

Skip SQLRules when:

• You need request/instance values as WHERE predicates (UserFilter(age=25) → age = 25). That is a query/filter library, not this compiler.
• You have a few static expressions and will never share constraint metadata with a Pydantic model — write SQLAlchemy clauses directly.
• You need portable regex with core alone — pattern requires a dialect plugin or custom translator.
• You expect dialect="postgresql" to load plugins — it is a hint only; pass plugins=[...] explicitly.
• You want a general-purpose query builder, ORM, or SQL string generator.

SQLRules pays off when the Pydantic model is the shared source of truth for constraint metadata across many fields or dialects.

Public API

sqlrules.compile(model, table, *, column_map=None, on_unsupported="raise", cache=True, emit_type_checks=False)
sqlrules.where(rules)           # prefer this to flatten expressions
sqlrules.flatten(rules)         # alias of where()
sqlrules.clear_model_cache()    # drop process-wide Phase-1 IR cache

compiler = sqlrules.Compiler(
    plugins=[...],           # optional SQLRulesPlugin instances
    on_conflict="raise",     # raise | replace | ignore
    dialect=None,            # hint only — does not load plugins
    on_unsupported="raise",
    cache=True,
    emit_type_checks=False,  # opt-in type_check IR (needs plugin translator)
)

Non-goals

SQLRules is not an ORM, validator, query builder, SQL string generator, migration tool, or database client. It only compiles supported Pydantic constraints into SQLAlchemy expressions. See design philosophy and non-goals.

Documentation

Full site: sqlrules.readthedocs.io

Topic	Link
Getting started	Guide
How-to guides	ORM binding · Markers · Examples
Upgrade	0.x → 1.0
Examples	examples/
Spec & constraints	SPEC · CONSTRAINTS
Plugins	Plugin system
API reference	Reference hub
FAQ	FAQ
Support	Support & compatibility
Roadmap	Roadmap
Changelog	Changelog

pip install -e ".[docs]"
make docs

Repo map

Path	Who cares
PyPI sqlrules / sqlrules-*	Application users — install these
examples/	Copy-paste runnable scripts
docs/	Spec, guides, architecture (also on Read the Docs)
packages/	Contributors — official dialect plugin sources
src/sqlrules/	Core library source
benchmarks/	Optional local compile benchmarks

Development (contributors)

make install
make check    # lint, types, tests, docs (matches most of CI)
make dist     # packaging smoke — required before release / to match full CI

See CONTRIBUTING.md. Maintainers: RELEASING.md.

License

MIT