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Multiple Inheritance Custom Django Field

I have two custom Django fields: JSONFieldand CompressedField, both of which work well. I would also like to have CompressedJSONField, and I rather hoped I could do this:

class CompressedJSONField(JSONField, CompressedField):
    pass

but upon import I get:

RuntimeError: maximum recursion depth exceeded while calling a Python object

I can find information on using multiple inheritance models in Django, but do nothing with fields. Should this be possible? Or should I just give up at this point?

change

To be clear, I don't think this has anything to do with the specifics of my code, as the following code has exactly the same problem:

class CustomField(models.TextField, models.CharField):
    pass

change 2:

I am currently using Python 2.6.6 and Django 1.3. Here is the full code of my example with the remote right down:

customfields.py

from django.db import models


class CompressedField(models.TextField):
    """ Standard TextField with automatic compression/decompression. """

    __metaclass__ = models.SubfieldBase
    description = 'Field which compresses stored data.'

    def to_python(self, value):
        return value

    def get_db_prep_value(self, value, **kwargs):
        return super(CompressedField, self)\
                        .get_db_prep_value(value, prepared=True)


class JSONField(models.TextField):
    """ JSONField with automatic serialization/deserialization. """

    __metaclass__ = models.SubfieldBase
    description = 'Field which stores a JSON object'

    def to_python(self, value):
        return value

    def get_db_prep_save(self, value, **kwargs):
        return super(JSONField, self).get_db_prep_save(value, **kwargs)


class CompressedJSONField(JSONField, CompressedField):
    pass

models.py

from django.db import models
from customfields import CompressedField, JSONField, CompressedJSONField

class TestModel(models.Model):

    name = models.CharField(max_length=150)
    compressed_field = CompressedField()
    json_field = JSONField()
    compressed_json_field = CompressedJSONField()

    def __unicode__(self):
        return self.name

compressed_json_field = CompressedJSONField(), Django.

+5
2

, JSON JSON, . JSON , , jusst __metaclass__ = models.SubfieldBase

, :

from django.db import models                                                       


class CompressedField(models.TextField):                                           
    """ Standard TextField with automatic compression/decompression. """           

    description = 'Field which compresses stored data.'                            

    def to_python(self, value):                                                    
        return value                                                               

    def get_db_prep_value(self, value, **kwargs):                                  
        return super(CompressedField, self).get_db_prep_value(value, prepared=True)


class JSONField(models.TextField):                                                 
    """ JSONField with automatic serialization/deserialization. """                

    description = 'Field which stores a JSON object'                               

    def to_python(self, value):                                                    
        return value 

    def get_db_prep_save(self, value, **kwargs):                                   
        return super(JSONField, self).get_db_prep_save(value, **kwargs)            


class CompressedJSONField(JSONField, CompressedField):                             
    __metaclass__ = models.SubfieldBase                                            

class TestModel(models.Model):                                                     

    name = models.CharField(max_length=150)                                        
    #compressed_field = CompressedField()                                          
    #json_field = JSONField()                                                      
    compressed_json_field = CompressedJSONField()                                  

    def __unicode__(self):                                                         
        return self.name

JSON Commpressed , , :

class JSONFieldSubClass(JSONField):
    __metaclass__ = models.SubfieldBase

... .

EDIT

class CompressedJSONField(JSONField, CompressedField):
    __metaclass__ = models.SubfieldBase

    def to_python(self, value):
        value = JSONField.to_python(self, value)
        value = CompressedField.to_python(self, value)
        return value

, to_python() to_python()

, ,

, super(class, self).method(args) to_python(), . , . http://docs.python.org/library/functions.html#super http://www.artima.com/weblogs/viewpost.jsp?thread=237121

class base1(object):                                                               
    def name(self, value):                                                         
        print "base1", value                                                       
        super(base1, self).name(value)                                             

    def to_python(self, value):                                                    
        value = value + " base 1 "                                                 
        if(hasattr(super(base1, self), "to_python")):                              
            value = super(base1, self).to_python(value)                            
        return value                                                               

class base2(object):                                                               
    def name(self, value):                                                         
        print "base2", value                                                       

    def to_python(self, value):                                                    
        value = value + " base 2 "                                                 
        if(hasattr(super(base2, self), "to_python")):                              
            value = super(base2, self).to_python(value)                            
        return value                                                               

class superClass(base1, base2):                                                    
    def name(self, value):                                                         
        super(superClass, self).name(value)                                        
        print "super Class", value
+2

, . , DJango, simlar ( )

: ImageFieldFile (ImageFile, FieldFile)
django/db/models/fields

-2

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