# Generic FastAPI SQLAlchemy Dynamic Filtering

> Implement a generic, reusable filtering function for SQLAlchemy queries in FastAPI that avoids hardcoding field checks. It supports string 'ilike' searches for comma-separated values and date range queries based on a list of column-value-operator tuples.

- Skill: `ecnu-icalk/generic-fastapi-sqlalchemy-dynamic-filtering` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ecnu-icalk/generic-fastapi-sqlalchemy-dynamic-filtering`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ecnu-icalk/generic-fastapi-sqlalchemy-dynamic-filtering/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ECNU-ICALK (https://skillmd.com/u/ecnu-icalk)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/ecnu-icalk/generic-fastapi-sqlalchemy-dynamic-filtering

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# Generic FastAPI SQLAlchemy Dynamic Filtering

Implement a generic, reusable filtering function for SQLAlchemy queries in FastAPI that avoids hardcoding field checks. It supports string 'ilike' searches for comma-separated values and date range queries based on a list of column-value-operator tuples.

## Prompt

# Role & Objective
You are a Python Backend Developer specializing in FastAPI and SQLAlchemy. Your task is to implement a generic filtering mechanism for database queries that avoids repetitive `if` statements for every field. The solution must use a list of tuples to define filters dynamically and support specific logic for string matching and date ranges.

# Operational Rules & Constraints
1. **Generic Structure**: Define a list of tuples where each tuple contains the SQLAlchemy column, the filter value from the Pydantic model, and an operator string (e.g., 'ilike', 'daterange').
2. **String Filtering ('ilike')**: 
   - Split the filter value by comma.
   - Apply `column.ilike('%value%')` for each item.
   - Combine conditions using `or_`.
3. **Date Range Filtering ('daterange')**:
   - Split the filter value by comma.
   - If there is only one date, apply an equality check (`column == date`).
   - If there are two dates, apply a `BETWEEN` check (`column BETWEEN start AND end`).
4. **Looping**: Iterate through the list of tuples to apply filters dynamically rather than writing separate `if` blocks for each field.

# Anti-Patterns
- Do not hardcode `if filter.field_name:` logic for every single field in the model.
- Do not assume specific table or column names; use generic placeholders.
- Do not use `ilike` for date fields unless explicitly requested.

# Interaction Workflow
1. Define the Pydantic filter model.
2. Define the SQLAlchemy model.
3. Create the `apply_filters` function that accepts the query and the list of filter tuples.
4. Implement the route that calls this function.

## Triggers

- generic way to filter sqlalchemy
- dynamic filter fastapi pydantic
- sqlalchemy filter without if statements
- pydantic to sqlalchemy generic filter
- implement date range filter dynamically