如何在 WTForms FieldList 中使用 FileField？使用 Flask-WTF 作为 FileField

问题描述 投票：0回答：1

我使用 WTForms FieldList、宏和 Javascript 创建了动态字段。

使用此代码验证许多字段（StringField、SelectField 等），我可以动态添加许多字段，它们验证和更新我的 Sqlite3 数据库。 不过我希望现在能够动态添加文件。

用于文件上传的标准 Flask-WTF 代码如下所示： 我如何利用它在 FieldList 表单上进行验证？

 if form.validate_on_submit():
    f_fileA = form.inputname.data
    filename_fileA = secure_filename(f_fileA.filename)
    f_fileA.save(os.path.join(
    UPLOAD_FOLDER, filename_fileA
    ))

我的代码 表格

forms.py

class ChildForm(Form):
    childAinput_1 = StringField(
        'ChildA input 1'
    )
    childAinput_2 = IntegerField(
        'ChildA input 2'
    )
    category = SelectField(
        'Category',
        choices=[('cat1', 'Category 1'), ('cat2', 'Category 2')]
    )
    fileA = FileField(
        'FileA'
    )


class MainForm(FlaskForm):
    parentinput_1 = StringField(
        'Parent input 1'
    )
    parentinput_2 = StringField(
        'Parent input 2'
    )
    childrenA = FieldList(
        FormField(ChildForm),
        min_entries=1,
        max_entries=20
    )

我的带有表单字段的 HTML 模板

form.html template

<a id="add" href="#">Add ChildA</a>
{# Show all subforms #}
        <form id="childA-form" action="" method="POST" role="form">
            {{ form.hidden_tag() }}

            {# show parents fields #}
            <div>
            {{ form.parentinput_1.label }}
            {{ form.parentinput_1 }}
        </div>
        <div>
            {{ form.parentinput_2.label }}
            {{ form.parentinput_2 }}
        </div>

            <div id="subforms-container">
                {% for subform in form.childrenA %}
                    {{ macros.render_childA_form(subform, loop.index0) }}
                {% endfor %}
            </div>

            <button type="submit">Send</button>
        </form>

        {% if form.errors %}
            {{ form.errors }}
        {% endif %}

        {# Form template #}
        {{ macros.render_childA_form(_template, '_') }}

当前表单验证（尚未添加文件上传）

routes.py

@bp.route('/', methods=['GET', 'POST'])
def index():
    form = MainForm()
    template_form = ChildForm(prefix='childrenA-_-')

    if form.validate_on_submit():
        # Create parent
        new_parent = Parent(
            parentinput_1 = form.parentinput_1.data,
            parentinput_2 = form.parentinput_2.data
        )

        db.session.add(new_parent)

        for childAe in form.childrenA.data:

            new_childA = ChildA(**childAe)

            # Add to parent
            new_parent.childrenA.append(new_childA)

        db.session.commit()

    return render_template(
        'index.html',
        form=form,
        _template=template_form
    )

以及宏（如果有用）：

macros.html

{%- macro render_childA_form(subform, index) %}
        <div id="childA-{{ index }}-form" class="{% if index != '_' %}subform{% else %}is-hidden{% endif %}" data-index="{{ index }}">
            <div>
                {{ subform.childAinput_1.label }}
                {{ subform.childAinput_1 }}
            </div>
            <div>
                {{ subform.childAinput_2.label }}
                {{ subform.childAinput_2}}
            </div>
            <div>
                {{ subform.category.label }}
                {{ subform.category }}
            </div>
            <div>
                {{ subform.fileA.label }}
                {{ subform.fileA }}
            </div>
    
            <a class="remove" href="#">Remove</a>
            <hr/>
        </div>
    {%- endmacro %}

我的模特

models.py
class Parent(db.Model):
    """Stores parents."""
    __tablename__ = 'parents'
    parentinput_1 = db.Column(db.String(100))
    parentinput_2 = db.Column(db.String(100))

    id = db.Column(db.Integer, primary_key=True)


class ChildA(db.Model):
    """Stores childrenA of a parent."""
    __tablename__ = 'childrenA'

    id = db.Column(db.Integer, primary_key=True)
    parent_id = db.Column(db.Integer, db.ForeignKey('parents.id'))

    childAinput_1 = db.Column(db.String(100))
    childAinput_2 = db.Column(db.Integer)
    category = db.Column(db.String(4))
    fileA = db.Column(db.String(255))

    # Relationship
    parent = db.relationship(
        'Parent',
        backref=db.backref('childrenA', lazy='dynamic', collection_class=list)
    )

（模型、路线和表格实际上在一个文件中，但我将它们拆分在问题中以便于阅读）

非常感谢

flask flask-sqlalchemy flask-wtforms wtforms
1个回答
0
投票

即使您使用 FormFields 列表，该过程也与标准示例代码中的过程相同。
您可以迭代所有嵌套表单并查询相应 FileField 的值并保存结果文件。

这是我基于您的代码部分的简单示例。

from flask import (
    Flask, 
    current_app, 
    redirect, 
    render_template, 
    url_for
)
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.orm import (
    DeclarativeBase, 
    Mapped 
)
from typing import List
from flask_wtf import FlaskForm
from flask_wtf.file import FileField
from wtforms import FieldList, FormField, SelectField, StringField
from werkzeug.utils import secure_filename
import os

class Base(DeclarativeBase):
    pass

db = SQLAlchemy(model_class=Base)

app = Flask(__name__)
app.config.from_mapping(
    SECRET_KEY='your secret here', 
    SQLALCHEMY_DATABASE_URI='sqlite:///example.db', 
    UPLOAD_FOLDER=os.path.join(app.static_folder, 'uploads')
)
db.init_app(app)

os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)

class Parent(db.Model):
    id:Mapped[int] = db.mapped_column(db.Integer, primary_key=True)
    input1:Mapped[str] = db.mapped_column(db.String)
    input2:Mapped[str] = db.mapped_column(db.String)
    children:Mapped[List['Child']] = db.relationship(back_populates='parent')

class Child(db.Model):
    id:Mapped[int] = db.mapped_column(db.Integer, primary_key=True)
    input1:Mapped[str] = db.mapped_column(db.String)
    category:Mapped[str] = db.mapped_column(db.String)
    parent_id:Mapped[int]= db.mapped_column(db.Integer, db.ForeignKey('parent.id'), nullable=False)
    parent:Mapped['Parent'] = db.relationship(back_populates='children')

with app.app_context():
    db.drop_all()
    db.create_all()

class ChildForm(FlaskForm):
    class Meta: 
        csrf = False

    input1 = StringField('Input 1')
    category = SelectField(
        'Category',
        choices=[('cat1', 'Category 1'), ('cat2', 'Category 2')]
    )
    file = FileField('File')

class MainForm(FlaskForm):
    input1 = StringField('Input 1')
    input2 = StringField('Input 2')
    
    children = FieldList(
        FormField(ChildForm),
        min_entries=1,
        max_entries=20
    )

@app.route('/', methods=['GET', 'POST'])
def index():
    form = MainForm()
    if form.validate_on_submit():
        parent = Parent(
            input1 = form.input1.data,
            input2 = form.input2.data,
        )

        for subform in form.children:
            child = Child()
            subform.form.populate_obj(child)

            file = subform.file.data
            file.save(os.path.join(
                current_app.config['UPLOAD_FOLDER'], 
                secure_filename(file.filename)
            ))

            parent.children.append(child)

        db.session.add(parent)
        db.session.commit()

        return redirect(url_for('index'))

    return render_template('index.html', **locals())

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Index</title>
    <style>
        fieldset[name^="child-"] {
            border: none; 
            border-top: 1px dotted #000; 
            padding: 0.32rem 0; 
            margin: 0.32rem 0;
        }
    </style>
</head>
<body>

    <form method="post" enctype="multipart/form-data">
        {{ form.hidden_tag() }}

        <div>
            {{ form.input1.label() }}
            {{ form.input1() }}
        </div>
        <div>
            {{ form.input2.label() }}
            {{ form.input2() }}
        </div>

        <div id="children">
            {% for subform in form.children -%}
            <fieldset name="child-{{ loop.index0 }}" style="display: flex;">
                <div style="flex-grow: 1;">
                {% for field in subform -%}
                    <div>
                        {{ field.label() }}
                        {{ field() }}
                    </div>
                {% endfor -%}
                </div>
                <div>
                    <button type="button" class="btn-remove">-</button>
                </div>
            </fieldset>
            {% endfor -%}
        </div>

        <div style="display: flex;">
            <div style="flex-grow: 1;">
                <button type="submit">Submit</button>
            </div>
            <div>
                <button type="button" id="btn-add">+</button>
            </div>
        </div>
    </form>

    <script>
        (function() {
            const childrensDiv = document.getElementById('children');

            const removeChildDiv = (event) => {
                if (childrensDiv.childElementCount > 1) {
                    event.target.closest('fieldset[name^="child-"]').remove();
                }
            };

            const addBtn = document.getElementById('btn-add');
            addBtn.addEventListener('click', () => {
                if (childrensDiv.childElementCount >= 1 && childrensDiv.childElementCount < 20) {
                    const newChildDiv = childrensDiv.lastElementChild.cloneNode(true); 
                    const fields = newChildDiv.querySelectorAll('input[name^="children-"], select[name^="children-"]');
                    fields.forEach(field => {
                        const nameAttr = field.name, 
                                newNameAttr = nameAttr.replace(
                                    /^children-(\d+)-(\w+)$/, 
                                    (match, p1, p2) => `children-${parseInt(p1)+1}-${p2}`
                                );
                        field.id = field.name = newNameAttr; 
                        field.value = '';

                        const label = newChildDiv.querySelector(`label[for="${nameAttr}"]`);
                        label.setAttribute('for', newNameAttr);
                    });

                    const rmBtn = newChildDiv.querySelector('.btn-remove');
                    rmBtn.addEventListener('click', removeChildDiv);

                    childrensDiv.appendChild(newChildDiv);
                }
            });

            document.querySelectorAll('.btn-remove').forEach(btn => {
                btn.addEventListener('click', removeChildDiv);
            });

        })();
    </script>
</body>
</html>
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