klg-asutk-app/backend/app/schemas/pagination.py

52 lines
1.5 KiB
Python

"""
Pagination schemas and utilities for multi-user server deployment.
Supports cursor-based and offset-based pagination.
"""
from typing import TypeVar, Generic, List, Optional
from pydantic import BaseModel, Field
from sqlalchemy.orm import Session, Query
T = TypeVar("T")
class PaginationParams(BaseModel):
"""Query params for pagination."""
page: int = Field(default=1, ge=1, description="Page number (1-based)")
per_page: int = Field(default=25, ge=1, le=100, description="Items per page (max 100)")
@property
def offset(self) -> int:
return (self.page - 1) * self.per_page
class PaginatedResponse(BaseModel, Generic[T]):
"""Standard paginated response wrapper."""
items: List[T]
total: int
page: int
per_page: int
pages: int
@classmethod
def from_query(cls, query: Query, params: PaginationParams, schema_cls=None):
total = query.count()
items = query.offset(params.offset).limit(params.per_page).all()
if schema_cls:
items = [schema_cls.model_validate(i) for i in items]
pages = (total + params.per_page - 1) // params.per_page
return cls(
items=items,
total=total,
page=params.page,
per_page=params.per_page,
pages=pages,
)
def paginate(db: Session, query, params: PaginationParams):
"""Apply pagination to a SQLAlchemy query. Returns (items, total)."""
total = query.count()
items = query.offset(params.offset).limit(params.per_page).all()
return items, total