select_schema functional

[igorbenav]

Using select_schema to Exclude Fields from Read Operations

Some database field types can cause issues in admin panels. The most common example is PostgreSQL's TSVector type used for full-text search, which can trigger NotImplementedError when trying to display records.

The select_schema parameter allows you to exclude problematic fields from all read operations while keeping them available for create/update operations.

Use select_schema when you encounter:

• TSVector fields causing NotImplementedError in admin views
• Large binary fields that slow down list views
• Computed fields that don't need to be displayed
• Sensitive fields that should be hidden from admin users
• Complex JSON fields that break admin display formatting

Basic Example: Excluding TSVector Fields

from sqlalchemy import Column, Integer, String, Text
from sqlalchemy_utils import TSVectorType
from pydantic import BaseModel
from typing import Optional
from datetime import datetime

# SQLAlchemy model with TSVector for full-text search
class Document(Base):
    __tablename__ = "documents"

    id = Column(Integer, primary_key=True)
    title = Column(String(200), nullable=False)
    content = Column(Text, nullable=False)
    created_at = Column(DateTime, default=func.now())

    # This field causes NotImplementedError in admin views
    search_vector = Column(TSVectorType('title', 'content'))

# Schemas for create/update (no search_vector)
class DocumentCreate(BaseModel):
    title: str = Field(..., min_length=1, max_length=200)
    content: str = Field(..., min_length=1)

class DocumentUpdate(BaseModel):
    title: Optional[str] = Field(None, min_length=1, max_length=200)
    content: Optional[str] = None

# Schema for read operations (excludes problematic field)
class DocumentSelect(BaseModel):
    id: int
    title: str
    content: str
    created_at: datetime
    # search_vector field intentionally excluded!

# Register with admin
admin.add_view(
    model=Document,
    create_schema=DocumentCreate,
    update_schema=DocumentUpdate,
    select_schema=DocumentSelect,  # ✅ TSVector excluded from reads
    allowed_actions={"view", "create", "update", "delete"}
)

Closes #21