如何使用Flex访问Django中的外键字段？ [英] How can I use Flex to access foreign-keyed fields in Django?

问题描述

我有以下Django和Flex代码：

I have the following Django and Flex code:

Django

class Author(models.Model):
  name = models.CharField(max_length=30)

class Book(models.Model):
  title = models.CharField(max_length=30)
  author = models.ForeignKeyField(Author)

Flex

package com.myproject.models.vo
{
    [Bindable]
    [RemoteClass(alias="myproject.models.Book")]

    public class BookVO
    {
        public var id:int;
        public var title:String;
        public var author: AuthorVO;
    }
}

正如你在这个例子中看到的，作者是外键我的书模型。现在我想在Flex中调用我的BookVO时收到作者的名字。因此，我希望以下代码可以正常工作，但是author_name会导致一个null：

As you can see in this example, Author is a foreign key in my Book model. Now I'd like to acccess the author's name when I call my BookVO in Flex. As such, I'd expect code like the following to work, but "author_name" results in a null:

var book = new BookVO();
var author_name = book.author.name;

我意识到我可以直接调用一个AuthorVO，但这个问题的关键是如何检索外部当您的VO绑定到远程对象时，使用Flex的键值？我目前正在使用PyAMF弥合Flex和Django之间的差距，但我不确定是否相关。

I realize I could call an AuthorVO directly, but the crux of this question is how can you retrieve foreign-keyed values using Flex when your VOs are bound to a remote object? I'm currently using PyAMF to bridge the gap between Flex and Django, but I'm not sure that's relevant.

推荐答案

Ok ，这是一个例子...

Ok, Here's an example...

模型：

class Logger(models.Model):
    lname = models.CharField(max_length=80)

    def __unicode__(self):
        return self.lname
    #
#

class DataSource(models.Model):
    dsname = models.CharField(max_length=80)
    def __unicode__(self):
        return self.dsname
    #
#

class LoggedEvent(models.Model):
    # who's data is this?
    who = models.ForeignKey(Logger)
    # what source?
    source = models.ForeignKey(DataSource)
    # the day (and, for some events also the time)
    when = models.DateTimeField()
    # the textual description of the event, often the raw data
    what = models.CharField(max_length=200)
    # from -1.0 to 1.0 this is the relative
    # importance of the event
    weight = models.FloatField()

    def __unicode__(self):
        return u"%2.2f %s:%s - %s" % (self.weight, self.source, self.who, self.what)
    #
#

这是我的amfgateway.py

Here's my amfgateway.py

def fetch_events(request, source):
    events = LoggedEvent.objects.select_related().all()
    return events
#

services = {
    'recall.fetch_events': fetch_events,
}

gateway = DjangoGateway(services)

，这是AMF电话接收方的Actionscript：

and here's my Actionscript for the receiving side of the AMF call:

protected function onRetrievedEvents(result: Object): void {

    for each(var evt: Object in result) {
        var who: Object = evt._who_cache.lname;

...

evt._who_cache.lname填充了select_related（）和缺少选择相关的缺失。如果我摆脱了select_related（）调用，那么我看到错误：

The evt._who_cache.lname is populated with the select_related() and missing when the select related is missing. If I get rid of the select_related() call, then I see the error:

TypeError: Error #1010: A term is undefined and has no properties.

您必须尝试与您的RemoteClass不同的技术...所以select_related可能不是问题在所有...（否则我的第一个答案将不会被否定。）剩下的取决于你。

You must be trying a different technique with your RemoteClass... so the select_related might not be the problem at all... (otherwise my first answer wouldn't have gotten negged.) The rest is up to you.

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