使用 Flask 和 render_template 显示 HTML 表格

Question

我想在使用 Google Cloud SQL 和 Google App Engine 的网站上显示一个表格。 我正在使用 Flask 和 pymysql。为了显示我的查询结果，我使用了 Flask 的 render_template。

我已经在这里找到了其他类似的主题（例如Topic: Listing table results to HTML with Flask），但是当我部署我的应用程序时仍然出现错误。似乎该错误与 for 循环有关。错误显示“jinja2.exceptions.TemplateSyntaxError: tag name expected”。

这是我收到的完整错误消息：

ERROR in app: Exception on /analysis [GET]
Traceback (most recent call last):    File "/env/lib/python3.7/site-packages/flask/app.py", line 2292, in wsgi_app      response = self.full_dispatch_request()
File "/env/lib/python3.7/site-packages/flask/app.py", line 1815, in full_dispatch_request      rv = self.handle_user_exception(e)
File "/env/lib/python3.7/site-packages/flask/app.py", line 1718, in handle_user_exception      reraise(exc_type, exc_value, tb)
File "/env/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise      raise value
File "/env/lib/python3.7/site-packages/flask/app.py", line 1813, in full_dispatch_request      rv = self.dispatch_request()
File "/env/lib/python3.7/site-packages/flask/app.py", line 1799, in dispatch_request      return self.view_functions[rule.endpoint](**req.view_args)
File "/srv/main.py", line 61, in analysis      return render_template("analysis.html", result = result)
File "/env/lib/python3.7/site-packages/flask/templating.py", line 134, in render_template      return _render(ctx.app.jinja_env.get_or_select_template(template_name_or_list),    File "/env/lib/python3.7/site-packages/jinja2/environment.py", line 869, in get_or_select_template      return self.get_template(template_name_or_list, parent, globals)
File "/env/lib/python3.7/site-packages/jinja2/environment.py", line 830, in get_template      return self._load_template(name, self.make_globals(globals))
File "/env/lib/python3.7/site-packages/jinja2/environment.py", line 804, in _load_template      template = self.loader.load(self, name, globals)
File "/env/lib/python3.7/site-packages/jinja2/loaders.py", line 125, in load      code = environment.compile(source, name, filename)
File "/env/lib/python3.7/site-packages/jinja2/environment.py", line 591, in compile      self.handle_exception(exc_info, source_hint=source_hint)
File "/env/lib/python3.7/site-packages/jinja2/environment.py", line 780, in handle_exception      reraise(exc_type, exc_value, tb)
File "/env/lib/python3.7/site-packages/jinja2/_compat.py", line 37, in reraise      raise value.with_traceback(tb)
File "/srv/templates/analysis.html", line 23, in template      <p class="p1"><span class="s1"><span class="Apple-tab-span"> </span>{% </span><span class="s2">for</span><span class="s1"> r </span><span class="s2">in</span><span class="s1"> result %}</span></p>
File "/env/lib/python3.7/site-packages/jinja2/environment.py", line 497, in _parse      return Parser(self, source, name, encode_filename(filename)).parse()
File "/env/lib/python3.7/site-packages/jinja2/parser.py", line 901, in parse      result = nodes.Template(self.subparse(), lineno=1)
File "/env/lib/python3.7/site-packages/jinja2/parser.py", line 883, in subparse      rv = self.parse_statement()
File "/env/lib/python3.7/site-packages/jinja2/parser.py", line 125, in parse_statement      self.fail('tag name expected', token.lineno)
File "/env/lib/python3.7/site-packages/jinja2/parser.py", line 59, in fail      raise exc(msg, lineno, self.name, self.filename)  jinja2.exceptions.TemplateSyntaxError: tag name expected

我在 main.py 中的代码：

    import logging
    import os
    from flask import Flask, render_template
    from flask import request
    import urllib.request
    from urllib.parse import parse_qs, urlparse
    import platform
    import pymysql
    import datetime

    db_user = os.environ.get('CLOUD_SQL_USERNAME')
    db_password = os.environ.get('CLOUD_SQL_PASSWORD')
    db_name = os.environ.get('CLOUD_SQL_DATABASE_NAME')
    db_connection_name = os.environ.get('CLOUD_SQL_CONNECTION_NAME')

    app = Flask(__name__)

    @app.route('/analysis', methods=['GET'])
    def analysis():
        if os.environ.get('GAE_ENV') == 'standard':
            unix_socket = '/cloudsql/{}'.format(db_connection_name)
            cnx = pymysql.connect(user=db_user, password=db_password,
                                  unix_socket=unix_socket, db=db_name)
        else:
            host = '127.0.0.1'
            #unix_socket = '/cloudsql/{}'.format(db_connection_name)
        cnx = pymysql.connect(user=db_user, password=db_password,
                                  unix_socket=unix_socket, db=db_name)
        with cnx.cursor() as cursor:
            sql = 'SELECT * FROM content'
            cursor.execute(sql)
            result = cursor.fetchall()
        cnx.close()
        return render_template("analysis.html", result = result)

if __name__ == '__main__':
    app.run(host='127.0.0.1', port=8080, debug=True)

文件分析.html：

<!doctype html>
<table>
<tr>
  <th>contentID</th>
  <th>timestamp</th> 
  <th>clientID</th>
  <th>content</th>
</tr>
{% for r in result %}
<tr>
  <td>{{ r[0] }}</td>
  <td>{{ r[1] }}</td> 
  <td>{{ r[2] }}</td>
  <td>{{ r[3] }}</td>
</tr>
{% endfor %}
</table>

您有什么建议我可以更改以使其正常工作吗？
提前致谢！

Answer 1

{% for r in result %}

<p class="p1">
<span class="s1">
<span class="Apple-tab-span">
</span>
</span><span class="s2">for</span><span class="s1"> {{ r }}</span><span class="s2">in</span><span class="s1">
</span>
</p>

{% endfor %}

Answer 2

您可以做到这一点的一种方法是首先拥有一个对象，或者使用 pandas 读取_csv，然后使用数据框的 to_html 方法。

如果您的数据已经正确格式化，这可以节省大量时间：

import pandas as pd
from flask import Flask, render_template

@app.route("/table-page", methods=['GET'])
def table():

    data_dic = {
        'id': [100, 101, 102],
        'color': ['red', 'blue', 'red']}
    columns = ['id', 'color']
    index = ['a', 'b', 'c']

    df = pd.DataFrame(data_dic, columns=columns, index=index)
    table = df.to_html(index=False)
    
    return render_template(
        "at-leaderboard.html",
        table=table)

现在您将 HTML 字符串粘贴到您的模板中，而无需将其作为 JSON 或需要 Jinja 模板格式的 dict 发送：

<html>
  <body>
    <div>
      {{ table | safe }}
    </div>
  </body>
</html>

Answer 3

根据堆栈跟踪，您用于analysis.html 的文本编辑器不是纯文本编辑器。它以其他格式保存文件，使其无效的 Jinja2 语法。

所以您在编辑器中看到的这一行：

{% for r in result %}

Python 将显示为（基于堆栈跟踪；为清楚起见添加了一些换行符）：

<p class="p1">
<span class="s1">
<span class="Apple-tab-span">
</span>
{% </span><span class="s2">for</span><span class="s1"> r </span><span class="s2">in</span><span class="s1"> result %}
</span>
</p>

要解决此问题，请在纯文本编辑器中打开文件 analysis.html 并根据需要进行编辑。