6.4 文件上传与处理

#### 6.4.1 文件上传表单

定义一个表单类，包含文件上传字段。

Python复制

```python
from flask_wtf import FlaskForm
from wtforms import FileField, SubmitField
from wtforms.validators import DataRequired

class UploadForm(FlaskForm):
    file = FileField('File', validators=[DataRequired()])
    submit = SubmitField('Upload')
```

#### 6.4.2 处理文件上传

在视图函数中处理文件上传，保存上传的文件到服务器。

Python复制

```python
from flask import request, redirect, url_for
from werkzeug.utils import secure_filename
import os

@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
    form = UploadForm()
    if form.validate_on_submit():
        file = form.file.data
        filename = secure_filename(file.filename)
        file.save(os.path.join('uploads', filename))
        return redirect(url_for('uploaded_file', filename=filename))
    return render_template('upload.html', form=form)
```

#### 6.4.3 文件存储

确保上传的文件存储在安全的位置，避免安全风险。

Python复制

```python
UPLOAD_FOLDER = 'uploads'
ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'}

app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS
```

------

通过本章的学习，你将掌握如何在Flask应用中处理表单，包括表单的基础知识、使用WTForms进行表单处理、表单验证以及文件上传与处理。这些知识将帮助你更好地实现用户与应用的交互。