I have a function which returns json data as history from Version of reversion.models.
from django.http import HttpResponse
from reversion.models import Version
from django.contrib.admin.models import LogEntry
import json
def history_list(request):
history_list = Version.objects.all().order_by('-revision__date_created')
data = []
for i in history_list:
data.append({
'date_time': str(i.revision.date_created),
'user': str(i.revision.user),
'object': i.object_repr,
'field': i.revision.comment.split(' ')[-1],
'new_value_field': str(i.field_dict),
'type': i.content_type.name,
'comment': i.revision.comment
})
data_ser = json.dumps(data)
return HttpResponse(data_ser, content_type="application/json")
When I run the above snippet I get the output json as
[{"type": "fruits", "field": "colour", "object": "anyobject", "user": "anyuser", "new_value_field": "{'price': $23, 'weight': 2kgs, 'colour': 'red'}", "comment": "Changed colour."}]
From the function above,
'comment': i.revision.comment
returns json as "comment": "changed colour" and colour is the field which I have written in the function to retrieve it from comment as
'field': i.revision.comment.split(' ')[-1]
But i assume getting fieldname and value from field_dict is a better approach
Problem: from the above json list I would like to filter new_field_value and old_value. In the new_filed_value only value of colour.
Getting the changed fields isn't as easy as checking the comment, as this can be overridden.
Django-reversion just takes care of storing each version, not comparing.
Your best option is to look at the django-reversion-compare module and its admin.py code.
The majority of the code in there is designed to produce a neat side-by-side HTML diff page, but the code should be able to be re-purposed to generate a list of changed fields per object (as there can be more than one changed field per version).
The code should* include a view independent way to get the changed fields at some point, but this should get you started:
from reversion_compare.admin import CompareObjects
from reversion.revisions import default_revision_manager
def changed_fields(obj, version1, version2):
"""
Create a generic html diff from the obj between version1 and version2:
A diff of every changes field values.
This method should be overwritten, to create a nice diff view
coordinated with the model.
"""
diff = []
# Create a list of all normal fields and append many-to-many fields
fields = [field for field in obj._meta.fields]
concrete_model = obj._meta.concrete_model
fields += concrete_model._meta.many_to_many
# This gathers the related reverse ForeignKey fields, so we can do ManyToOne compares
reverse_fields = []
# From: http://stackoverflow.com/questions/19512187/django-list-all-reverse-relations-of-a-model
changed_fields = []
for field_name in obj._meta.get_all_field_names():
f = getattr(
obj._meta.get_field_by_name(field_name)[0],
'field',
None
)
if isinstance(f, models.ForeignKey) and f not in fields:
reverse_fields.append(f.rel)
fields += reverse_fields
for field in fields:
try:
field_name = field.name
except:
# is a reverse FK field
field_name = field.field_name
is_reversed = field in reverse_fields
obj_compare = CompareObjects(field, field_name, obj, version1, version2, default_revision_manager, is_reversed)
if obj_compare.changed():
changed_fields.append(field)
return changed_fields
This can then be called like so:
changed_fields(MyModel,history_list_item1, history_list_item2)
Where history_list_item1 and history_list_item2 correspond to various actual Version items.
*: Said as a contributor, I'll get right on it.