blocks|key|153123|text|我之前也遇到过类似的事情。我试图使用model_form来解决这个问题，但它不能完全解决动态添加新条目的问题，而且我在处理关系时很难使用它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|153124|在WTForms中使用QuerySelectField只会帮助你填充例如。具有id的<+select+>，值对对应于现有地址。但它仍然在模板中呈现为常规的html形式。|153125|通过使用某种类型的多选，可以在前端dynamically+add新的选项，您可以以相同的形式发送额外的地址。如果数据库中不存在新地址，则端点将负责创建新地址。|offset|length|153126|WTForm表单将为：|153127|from+app+import+db

class+PersonAddressForm(Form):
++++id+=+HiddenField('id')
++++name+=+StringField('Name')
++++addresses+=+QuerySelectField('Addresses',+
++++++++++++query_factory=lambda:+db.session.query(Address),+
++++++++++++get_pk=lambda+a:+a.id,+get_label=lambda+a:+a.name)

++++#+Custom+validate
++++def+validate(self):
++++++++#+...+custom+validation
++++++++return+True|code-block|syntax|javascript|153128|路由类似于：|153129|#+...+this+will+be+used+to+create+and+update+a+user
@route('create/<userid>',+methods=["GET"])
def+get_user_form(userid):
++++#+...+Get+the+Person
++++user+=+Person()
++++if+userid:
++++++++#+...+if+userid+supplied,+use+existing+Person+object
++++++++user+=+Person.query.get(userid)

++++#+...+Populate+the+form
++++person_form+=+PersonAddressForm(obj=user)

++++#+...+return+form
++++return+render_template('somepage.html',+form=person_form)

@route('create/<userid>',+methods=["POST"])
def+post_person_form(userid):
++++person_form+=+PersonAddressForm(request.form)

++++if+person_form.validate():
++++++++#+...+Get+db+object
++++++++person+=+db.session.query(Person).get(form.id)

++++++++#+...+Add+changes+to+the+object+from+the+form
++++++++person_form.populate_obj(obj=person_address)

++++++++#+...+Get+addresses
++++++++addresses+=+form.addresses.raw_data

++++++++#+...+loop+over+and+add+to+person
++++++++for+address+in+addresses:
++++++++++++#+Add+or+create+an+address
++++++++++++actual_address+=+db.session.query(Address).get(address.id)

++++++++++++#+...+check+if+address+is+existing
++++++++++++if+not+actual_address:
++++++++++++++++#+...+if+address+not+existing,+create+new+one
++++++++++++++++actual_address+=+Address(address.name)
++++++++++++++++db.session.add(actual_address)

++++++++++++#+...+Append+new+or+created+address+to+person
++++++++++++person.addresses.append(actual_address)

++++++++#+...+save+changes+to+the+db
++++++++db.session.commit()

++++++++#+...+Update/Create+complete
++++++++return+redirect(url_for('get_users'))

++++else:
++++++++#+...+form+not+valid,+notify+user
++++++++#+...|153130|这将处理编辑/创建用户和创建地址。以及创建它们之间的关系。要使其也支持删除地址，请更改|153131|person.addresses.append(actual_address)|153132|至|153133|person.addresses+=+list_of_actual_addresses|153134|并在person模型中进行更改(cascade='delete-orphan')|153135|addresses+=+db.relationship('Address',+secondary=personaddress,+cascade='delete-orphan'+backref=db.backref('person',+lazy='dynamic'))|153136|这将使表单每次更新整个地址关系，级联将删除孤立地址。因此，每次提交表单时，都会更新一个人的整个地址列表。|153137|在处理模板中的WTForms时，如果您还没有使用宏，我强烈建议您使用宏。您必须在某种程度上重写它，但请查看this。|153138|希望这能有所帮助|153139|entityMap|0|LINK|mutability|MUTABLE|url|http://jsfiddle.net/8xL4gsmk/2/|1|http://bear-z.com/python/render-bootstrap-3-forms-with-wtforms-and-jinja/^0|0|0|H|F|0|0|0|0|0|0|0|0|0|0|0|0|0|1H|4|1|0|0^^$0|@$1|2|3|4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1L|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1M|8|@]|9|@$F|1N|G|1O|1|1P]]|A|$]]|$1|H|3|I|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|1R|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1S|8|@]|9|@]|A|$]]|$1|Q|3|R|5|L|7|1T|8|@]|9|@]|A|$M|N]]|$1|S|3|T|5|6|7|1U|8|@]|9|@]|A|$]]|$1|U|3|V|5|L|7|1V|8|@]|9|@]|A|$M|N]]|$1|W|3|X|5|6|7|1W|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|L|7|1X|8|@]|9|@]|A|$M|N]]|$1|10|3|11|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|12|3|13|5|L|7|1Z|8|@]|9|@]|A|$M|N]]|$1|14|3|15|5|6|7|20|8|@]|9|@]|A|$]]|$1|16|3|17|5|6|7|21|8|@]|9|@$F|22|G|23|1|24]]|A|$]]|$1|18|3|19|5|6|7|25|8|@]|9|@]|A|$]]|$1|1A|3|-4|5|6|7|26|8|@]|9|@]|A|$]]]|1B|$1C|$5|1D|1E|1F|A|$1G|1H]]|1I|$5|1D|1E|1F|A|$1G|1J]]]]

I have also encountered something similar earlier. I tried to solve it by using model_form, but it doesn't quite solve the problem of adding new entries dynamically, and I was having a hard time using it when dealing with relations.

Using the QuerySelectField in WTForms will only help you populating eg. an &lt; select > with id, value pairs corresponding to the existing addresses. But it still renders to a regular html form in the template.

By using some sort of multiselect with the possibility to <a href="http://jsfiddle.net/8xL4gsmk/2/" rel="nofollow">dynamically add</a> new options in the frontend you can send additional addresses in the same form. The the endpoint will take care of creating new Addresses if they don't exist in the db.

The WTForm form would be:

<pre><code>from app import db

class PersonAddressForm(Form):
 id = HiddenField('id')
 name = StringField('Name')
 addresses = QuerySelectField('Addresses', 
 query_factory=lambda: db.session.query(Address), 
 get_pk=lambda a: a.id, get_label=lambda a: a.name)

 # Custom validate
 def validate(self):
 # ... custom validation
 return True
</code></pre>

And the route something like:

<pre><code># ... this will be used to create and update a user
@route('create/&lt;userid&gt;', methods=["GET"])
def get_user_form(userid):
 # ... Get the Person
 user = Person()
 if userid:
 # ... if userid supplied, use existing Person object
 user = Person.query.get(userid)

 # ... Populate the form
 person_form = PersonAddressForm(obj=user)

 # ... return form
 return render_template('somepage.html', form=person_form)

@route('create/&lt;userid&gt;', methods=["POST"])
def post_person_form(userid):
 person_form = PersonAddressForm(request.form)

 if person_form.validate():
 # ... Get db object
 person = db.session.query(Person).get(form.id)

 # ... Add changes to the object from the form
 person_form.populate_obj(obj=person_address)

 # ... Get addresses
 addresses = form.addresses.raw_data

 # ... loop over and add to person
 for address in addresses:
 # Add or create an address
 actual_address = db.session.query(Address).get(address.id)

 # ... check if address is existing
 if not actual_address:
 # ... if address not existing, create new one
 actual_address = Address(address.name)
 db.session.add(actual_address)

 # ... Append new or created address to person
 person.addresses.append(actual_address)

 # ... save changes to the db
 db.session.commit()

 # ... Update/Create complete
 return redirect(url_for('get_users'))

 else:
 # ... form not valid, notify user
 # ...
</code></pre>

This will handle edit/create user and create Address. As well as create the relation between. To make it also support delete Address, change 

<pre><code>person.addresses.append(actual_address)
</code></pre>

to

<pre><code>person.addresses = list_of_actual_addresses
</code></pre>

and change this in the person model (cascade='delete-orphan')

<pre><code>addresses = db.relationship('Address', secondary=personaddress, cascade='delete-orphan' backref=db.backref('person', lazy='dynamic'))
</code></pre>

This will make the form update the entire address relation each time and the cascade will delete orphaned addresses. So the entire addresses list for a person would be updated each time the form is submitted.

When dealing with WTForms in templates i highly recommend using macros if you don't already. You would have to rewrite it to some degree, but check <a href="http://bear-z.com/python/render-bootstrap-3-forms-with-wtforms-and-jinja/" rel="nofollow">this</a> out.

Hope this helps

I want to create a form for many-to-many relations using Flask, SQLAlchemy and WTForms that represents these models:

<pre><code>personaddress = db.Table('personaddress',
 db.Column('person', db.Integer, db.ForeignKey('person.id')),
 db.Column('address', db.Integer, db.ForeignKey('address.id'))
)

class Person(db.Model):
 __tablename__ = "person"
 id = db.Column(Integer, primary_key=True)
 name = db.Column(String, nullable=False)
 addresses = db.relationship('Address', secondary=personaddress, backref=db.backref('person', lazy='dynamic'))

class Address(db.Model):
 __tablename__ = "address"
 id = db.Column(db.Integer, primary_key=True)
 name = db.Column(db.String, nullable=False)
</code></pre>

Requirements

Now I want to create a single page that contains forms to achieve the following:

<ul>
<li>add/edit/delete a person</li>
<li>add/edit/delete a address</li>
<li>add/edit/delete a relation between a person and an address</li>
</ul>

Important requirement: Using QuerySelectField, I can choose existing addresses for a person. But I want to add new addresses in the same form.

I've played around with <code>model_form</code> for the main models and subforms using <code>FormField</code> for the junction table but I just can't figure out how to update everything including the foreign key relations. The page should have a single submit button for all forms and subforms displayed.

Questions

<ol>
<li>How are the above requirements typically implemented in Flask?</li>
<li>Is this many-to-many scenario something that Django can handle more easily through its admin interface?</li>
</ol>

Update many-to-many relationships using Flask, SQLAlchemy and WTForms?

我想使用Flask、SQLAlchemy和WTForms为多对多关系创建一个表单来表示这些模型：personaddress = db.Table('personaddress',    db.Column('person', db.Integer, db.ForeignKey('person.id')),    db....

问使用Flask、SQLAlchemy和WTForms更新多对多关系？
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