@app.route('/api/tstj/') def get_book_data(): sql2 = 'select * from book' data = sql_query_json(sql2) for item in data: item['price'] = str(item['price'].quantize(Decimal('0.00'))) if item['price'] else item['price'] item['uploadtime'] = item['uploadtime'].strftime("%Y-%m-%d") if item['uploadtime'] else item['uploadtime'] item['borrowtime'] = item['borrowtime'].strftime("%Y-%m-%d") if item['borrowtime'] else item['borrowtime'] item['returntime'] = item['returntime'].strftime("%Y-%m-%d") if item['returntime'] else item['returntime'] print(data) return {'result':data,'code':200} 解释每行代码的意思

Sure, here is the explanation of each line of code:

1. `@app.route('/api/tstj/')`: This line creates a route for the `/api/tstj/` endpoint in the Flask application.

2. `def get_book_data():`: This line defines a function named `get_book_data` that will handle the requests to the `/api/tstj/` endpoint.

3. `sql2 = 'select * from book'`: This line defines a SQL query to select all columns from the `book` table.

4. `data = sql_query_json(sql2)`: This line executes the SQL query defined in the previous line using the `sql_query_json()` function and saves the results to the `data` variable.

5. `for item in data:`: This line starts a loop that iterates over each item in the `data` list.

6. `item['price'] = str(item['price'].quantize(Decimal('0.00'))) if item['price'] else item['price']`: This line converts the `price` value of the current item to a string with two decimal places using the `quantize()` method of the `Decimal` class. If the `price` value is `None`, it is left unchanged.

7. `item['uploadtime'] = item['uploadtime'].strftime("%Y-%m-%d") if item['uploadtime'] else item['uploadtime']`: This line converts the `uploadtime` value of the current item to a string in the format `YYYY-MM-DD` using the `strftime()` method of the `datetime` class. If the `uploadtime` value is `None`, it is left unchanged.

8. `item['borrowtime'] = item['borrowtime'].strftime("%Y-%m-%d") if item['borrowtime'] else item['borrowtime']`: This line converts the `borrowtime` value of the current item to a string in the format `YYYY-MM-DD` using the `strftime()` method of the `datetime` class. If the `borrowtime` value is `None`, it is left unchanged.

9. `item['returntime'] = item['returntime'].strftime("%Y-%m-%d") if item['returntime'] else item['returntime']`: This line converts the `returntime` value of the current item to a string in the format `YYYY-MM-DD` using the `strftime()` method of the `datetime` class. If the `returntime` value is `None`, it is left unchanged.

10. `print(data)`: This line prints the `data` list to the console.

11. `return {'result':data,'code':200}`: This line returns a dictionary with two keys: `result` and `code`. The `result` key maps to the `data` list (after the modifications made in the loop), and the `code` key maps to the HTTP status code `200` (OK).