@app.route('/check', methods=['GET', 'POST'])
def check():
    form = CheckForm()    
    id_list = [str(val) for val, in db.session.query(Docs.id).all()]
    name_list = [val for val, in db.session.query(Docs.name).all()]
    date_of_creation_list = [val.strftime('%d-%m-%Y') for val, in 
                            db.session.query(Docs.date_of_creation)]
    count = db.session.query(Docs).count()
    
    if files_count_discrepancy() == True or file_names_discrepancy() == True:
        message = """
            Data Security at Risk. 
            Information about the number of files is not reliable. 
            Or the names do not matched
            """
        flash(message)        
        
    return render_template('check.html', form = form, 
                                        id_list = id_list,
                                        name_list = name_list,
                                        date_of_creation_list = date_of_creation_list,
                                        count = count)

 ...
<form action="" method="POST">    
            
                <div class="table-wrapper">
                <input class="form-control" id="Input" type="text" placeholder="Search">
                <br>
                <table class="table table-bordered table-dark">
                    <thead>
                        <tr>
                            <th scope="col">#</th>
                            <th scope="col">FIle</th>
                            <th scope="col">Name</th>
                            <th scope="col">Date of creation</th>
                        </tr>
                    </thead>
                    <tbody id="DocsTable">
                        {% for i in range(0, count) %}
                        <tr>
                            <td>
                                <label class="custom-control-input">{{ loop.index }}</label>
                                {{ form.checkbox }}
                            </td>
                            <td>{{ form.file_name(value=id_list[i]) }}</td>
                            <td>{{ name_list[i] }}</td>
                            <td>{{ date_of_creation_list[i] }}</td>
                        </tr>
                        {% endfor %}
                    </tbody>
                </table>
                </div>
            </form>
...

 class CheckForm(FlaskForm):
    checkbox = BooleanField()
    file_name = StringField(validators=[DataRequired()])