我想将所有模型数据导出到CSV文件中：
models.py

import ast
import uuid
import base64
from django.db import models
from django.contrib import admin
from qlu.settings import HOST_NAME,STATS_URI
from django.core.validators import URLValidator
#------------------------------------------------------------------------------ 

class short_url(models.Model):
    """
        This is a short_url class 
    """
    blocked = models.BooleanField(default=False)                                # To check whether URL is blocked or not 
    updated_at = models.DateTimeField(auto_now=True)                            # When URL is updated
    url = models.TextField(validators=[URLValidator()])                         # URL entered by the user
    created_at = models.DateTimeField(auto_now_add=True)                        # When URL is created
    url_hash = models.CharField(max_length=10,unique=True,db_index=True)        # base64 encoded URL id  

    def _generateShortUrl(self):
        """
            This function will generate base64 encoded URL hash
        """
        hash = base64.urlsafe_b64encode(uuid.uuid1().bytes)[:6]
        hash_exist = short_url.objects.filter(url_hash=hash)
        while hash_exist:
            hash = base64.urlsafe_b64encode(uuid.uuid1().bytes)[:6]
            hash_exist = short_url.objects.filter(url_hash=hash)        
            continue       
        return hash 

    def save(self, *args, **kwargs):
        """
            Custom Save method for link model 
        """
        self.url_hash = self._generateShortUrl()        
        super(short_url, self).save(*args, **kwargs)    

    def get_short_url(self):
        """
            This method returns the url_hash related to the url 
        """
        return HOST_NAME + self.url_hash

    def get_stats_url(self):
        """
            This method returns the stats page URL for a url_hash
        """        
        return HOST_NAME + self.url_hash + STATS_URI

    def __unicode__(self):
        """
            This method convert Django model object to the user readable string 
        """
        return unicode(self.url)

class click_info(models.Model):
    """
        This is a click_info class 
    """
    user_ip = models.TextField()                                                # Store the user_ip
    user_agent = models.TextField()                                             # Store the user_agent
    http_refrer = models.TextField()                                            # Store the http_refrer
    hash = models.ForeignKey(short_url)                                         # base64 encoded URL id
    get_parameters = models.TextField()                                         # Store other get_parameters
    request_time = models.DateTimeField()                                       # When user made the request_time
    updated_at = models.DateTimeField(auto_now=True)                            # When click_info is updated
    created_at = models.DateTimeField(auto_now_add=True)                        # When click is created

    def get_parameters_dict(self):
        """
            This method returns the get parameter dict
        """
        return ast.literal_eval(self.get_parameters)

    def __unicode__(self):
        """
            This method convert Django model object to the user readable string 
        """
        return unicode(self.hash)

#------------------------------------------------------------------------------ 

class short_url_admin(admin.ModelAdmin):
    """
        short_url_admin class
    """
    list_display = ('url','blocked','updated_at',
                    'created_at','url_hash')
    exclude = ('url_hash',)

class url_info_admin(admin.ModelAdmin):
    """
        url_info_admin class
    """
    list_display = ('user_ip','user_agent','http_refrer',
                    'hash','request_time','get_parameters_dict')    

#------------------------------------------------------------------------------ 
admin.site.register(short_url,short_url_admin)
admin.site.register(click_info,url_info_admin)

做这件事的最好方法是什么？