# 项目文件：shelf_project/src/shelfweb/errors.py
import json
import sqlite3

from flask import current_app, render_template, request
from werkzeug.exceptions import HTTPException, InternalServerError


def http_error(error):
    response = error.get_response()  # 保留 405 的 Allow 等响应头。
    if request.path.startswith("/api/"):
        response.set_data(
            json.dumps(
                {"error": {"status": error.code, "message": error.description}},
                ensure_ascii=False,
            )
        )
        response.content_type = "application/json"
    else:
        response.set_data(
            render_template("error.html", status=error.code, message=error.description)
        )
        response.content_type = "text/html; charset=utf-8"
    return response


def database_error(error):
    current_app.logger.error("数据库操作失败：%s", type(error).__name__)
    return http_error(InternalServerError(description="数据库操作失败，请稍后重试"))


def init_app(app):
    app.register_error_handler(HTTPException, http_error)
    app.register_error_handler(sqlite3.DatabaseError, database_error)

<!-- 项目文件：shelf_project/src/shelfweb/templates/error.html -->
{% extends 'base.html' %}
{% block title %}请求未完成{% endblock %}
{% block content %}
<section class="panel form-panel"><p class="eyebrow">HTTP {{ status }}</p>
  <h1>请求未完成</h1><p role="alert">{{ message }}</p>
  <p><a href="{{ url_for('shelf.index') }}">返回书架</a> · <a href="{{ url_for('auth.login') }}">前往登录</a></p>
</section>
{% endblock %}