Flask前端推荐课程表格无法渲染数据的问题求助

大家好，我最近在做Flask项目的一个功能时遇到了个头疼的问题：后台日志里能看到推荐课程的数据已经正确获取，前端页面加{{ recommended_courses }}调试时也能看到完整的原始数据，但页面上的课程表格就是空的，完全没渲染出任何课程行。

下面是我的相关代码：

前端模板代码 #

<!-- Debug: {{ recommended_courses }} -->
<section id="recommended-courses" class="dashboard-section">
    <h2 class="section-title"><i class="fas fa-book-open"></i> Recommended Courses</h2>
    {% if recommended_courses %}
    <p>Debug: {{ recommended_courses }}</p>
    <div class="table-container">
        <table class="data-table">
            <thead>
                <tr>
                    <th>Course Code</th>
                    <th>Course Name</th>
                    <th>Credit Hours</th>
                    <th>Course Type</th>
                    <th>Semester</th>
                    <th>Prerequisite</th>
                </tr>
            </thead>
            <tbody>
                {% for course in recommended_courses %}
                <tr>
                    <td>{{ course.course_code }}</td>
                    <td>{{ course.course_name }}</td>
                    <td>{{ course.credit_hours }}</td>
                    <td>{{ course.course_type }}</td>
                    <td>{{ course.semester }}</td>
                    <td>{{ course.prerequisite or 'None' }}</td>
                </tr>
                {% endfor %}
            </tbody>
        </table>
    </div>
    {% else %}
    <p>No recommended courses available.</p>
    {% endif %}
</section>

Flask路由代码 #

@app.route('/advising', methods=['GET', 'POST'])
@login_required
def advising():
    logger.debug(f"Advising route accessed by user {current_user.id}")

    # Authorization Check
    if current_user.user_type_ID != 1:
        flash('Access denied. You are not an advisor.', 'error')
        return redirect(url_for('dashboard'))

    try:
        # Fetch advisor details
        advisor_id = functions.get_advisor_id(current_user.id)
        logger.debug(f"Fetched advisor ID: {advisor_id}")
        if not advisor_id:
            flash('Advisor ID not found. Please try again.', 'error')
            return redirect(url_for('dashboard'))

        advisor_info = functions.fetch_advisor_info(advisor_id)
        logger.debug(f"Fetched advisor info: {advisor_info}")
        if not advisor_info:
            flash('Unable to load advisor information. Please contact support.', 'error')
            return redirect(url_for('dashboard'))

        # Initialize context variables
        student_info = None
        gpa_deficit = 0
        probation_status = False
        consecutive_semesters = 0
        transcript = None
        recommended_courses = None

        # Handle student search
        if request.method == 'POST' and 'search_student' in request.form:
            student_id = request.form.get('student_id')
            logger.debug(f"Received student search request with student_ID: {student_id}")
            if student_id:
                try:
                    # Resolve student_ID to user_ID
                    user_id = functions.get_user_id_from_student_id(student_id)
                    if not user_id:
                        logger.warning(f"No user_ID found for student_ID: {student_id}")
                        flash(f"Student with ID {student_id} not found.", 'error')
                    else:
                        # Fetch student info using user_ID
                        student_info = functions.fetch_student_info_by_id(user_id)
                        logger.debug(f"Fetched student info for user_ID {user_id}: {student_info}")
                        if student_info:
                            # Fetch additional student data
                            gpa_deficit = functions.calculate_gpa_deficit(user_id)
                            logger.debug(f"GPA Deficit: {gpa_deficit}")
                            con_sem = functions.probation_semesters_count(user_id)
                            logger.debug(f"Consecutive semesters on probation: {con_sem}")
                            probation_status = functions.check_probation_status(user_id, con_sem)
                            logger.debug(f"Probation Status: {probation_status}")
                            consecutive_semesters = functions.count_consecutive_probation_semesters(user_id)
                            logger.debug(f"Consecutive Semesters on Probation: {consecutive_semesters}")
                            transcript = functions.fetch_student_transcript(user_id)
                            logger.debug(f"Fetched transcript: {transcript}")
                            sttran = functions.student_transcript(user_id)
                            logger.debug(f"Fetched sttran: {sttran}")

                            # Validate transcript structure
                            if not isinstance(sttran, list):
                                logger.error("Transcript is not a list. Invalid structure.")
                                raise ValueError("Transcript data is not in expected format.")

                            # Ensure every item in the transcript is a dictionary
                            sttran = [
                                course for course in sttran
                                if isinstance(course, dict) and 'grade' in course and 'course_code' in course
                            ]

                            # Filter transcript data
                            filtered = [
                                course for course in sttran
                                if course['grade'] not in ['W', 'P', 'F', 'FA', 'I']
                            ]
                            completed_courses = [course['course_code'] for course in filtered]
                            completed_course_types = {
                                course['course_type']: completed_courses.count(course['course_type'])
                                for course in filtered
                            }
                            recommended_courses = functions.recommend_courses(
                                user_id, 
                                student_info['cumulative_gpa'],
                                completed_courses,
                                completed_course_types,
                                probation_status,
                                con_sem
                            )
                            logger.debug(f"Fetched recommended courses: {recommended_courses}")
                        else:
                            logger.warning(f"No data found for user_ID: {user_id}")
                            flash(f"Student with ID {student_id} not found.", 'error')
                except Exception as e:
                    logger.error(f"Error during student search for student_ID {student_id}: {str(e)}", exc_info=True)
                    flash("An error occurred while searching for the student.", "error")

        # Fetch availability slots for advisor
        advisor_slots = functions.fetch_availability_slots(advisor_id)
        logger.debug(f"Fetched advisor slots: {advisor_slots}")

        # Render the page with all required context
        return render_template(
            'advising.html',
            advisor_info=advisor_info,
            advisor_slots=advisor_slots,
            student_info=student_info,
            gpa_deficit=gpa_deficit,
            probation_status=probation_status,
            consecutive_semesters=consecutive_semesters,
            transcript=transcript,
            recommended_courses=recommended_courses,
        )

    except Exception as e:
        logger.error(f"Unexpected error in advising route: {str(e)}", exc_info=True)
        flash('An error occurred while loading the advising page. Please try again later.', 'error')
        return redirect(url_for('dashboard'))

我已经确认recommended_courses在后台日志和前端调试中都有数据，但表格就是不渲染。有没有大佬能帮我分析一下可能的原因，或者给我一些排查的方向？

备注：内容来源于stack exchange，提问作者Youssef Ahmed