Source code for superdjango.contrib.history.models

# Imports

import difflib
from django.conf import settings
from django.db import models
from django.utils.translation import ugettext_lazy as _
from superdjango.db.history.models import HistoryModel

# Exports

__all__ = (
    "History",
)

# Constants

AUTH_USER_MODEL = settings.AUTH_USER_MODEL

# Models


class History(HistoryModel):
    """An entry in the record history timeline."""

    field_changes = models.TextField(
        _("field changes"),
        blank=True,
        help_text=_("Fields that changed as part of the history."),
        null=True
    )

    class Meta:
        get_latest_by = "added_dt"
        ordering = ["-added_dt"]
        verbose_name = _("History Entry")
        verbose_name_plural = _("History Entries")

    @classmethod
    def log_field_changes(cls, instance, verb, fields=None):
        """Log changes to fields to the ``field_changes`` field of the history record."""
        if fields is None:
            return

        a = list()
        for change in fields:
            # Attempt to make text fields or long character fields look good.
            if len(str(change.new_value)) > 128 or len(str(change.old_value)) > 128:
                b = list()
                diff = difflib.Differ()
                for i in diff.compare(str(change.old_value).splitlines(), str(change.new_value).splitlines()):
                    b.append(i.strip())

                a.append(" ".join(b))
            else:
                a.append(str(change))

        instance.field_changes = "\n\n".join(a)
        instance.save(update_fields=["field_changes"])