Btukfyl

I would like to show a table on a website using Google Cloud SQL and Google App Engine.
I am using Flask and pymysql. To show the result of my query I use the render_template of Flask.

I already found other similar topics here (like Topic: Listing table results to HTML with Flask), but I still get an error when I deploy my app. It seems that the error has to do with the for loop.. The error says "jinja2.exceptions.TemplateSyntaxError: tag name expected".

Here's the full error message I get:

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

My Code in main.py:

    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)

File analysis.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>

Do you have any suggestions what I can can change to make it work?

Thanks in advance!

Based on the stack trace, the text editor you're using for analysis.html isn't a plain text editor. It's saving the file in some other format, making it invalid Jinja2 syntax.

So this line that you see in your editor:

{% for r in result %}

Python will see as (based on the stack trace; added some line breaks for clarity):

<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>

To fix the problem, open the file analysis.html in a plain text editor and edit it as needed.