Add file metadata app

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/file_metadata/models.py

@@ -0,0 +1,119 @@
+from __future__ import unicode_literals
+
+import logging
+
+from django.db import models
+from django.utils.encoding import python_2_unicode_compatible
+from django.utils.functional import cached_property
+from django.utils.module_loading import import_string
+from django.utils.translation import force_text
+from django.utils.translation import ugettext_lazy as _
+
+from mayan.apps.documents.models import DocumentType, DocumentVersion
+
+from .managers import DocumentTypeSettingsManager
+
+logger = logging.getLogger(__name__)
+
+
+@python_2_unicode_compatible
+class StoredDriver(models.Model):
+    driver_path = models.CharField(
+        max_length=255, verbose_name=_('Driver path')
+    )
+    internal_name = models.CharField(
+        db_index=True, max_length=128, verbose_name=_('Internal name')
+    )
+
+    class Meta:
+        ordering = ('internal_name',)
+        verbose_name = _('Driver')
+        verbose_name_plural = _('Drivers')
+
+    def __str__(self):
+        return force_text(self.driver_label)
+
+    @cached_property
+    def driver_class(self):
+        return import_string(self.driver_path)
+
+    @cached_property
+    def driver_label(self):
+        return self.driver_class.label
+
+
+@python_2_unicode_compatible
+class DocumentVersionDriverEntry(models.Model):
+    driver = models.ForeignKey(
+        related_name='driver_entries', to=StoredDriver,
+        verbose_name=_('Driver')
+    )
+    document_version = models.ForeignKey(
+        related_name='file_metadata_drivers', to=DocumentVersion,
+        verbose_name=_('Document version')
+    )
+
+    class Meta:
+        ordering = ('document_version', 'driver')
+        unique_together = ('driver', 'document_version')
+        verbose_name = _('Document version driver entry')
+        verbose_name_plural = _('Document version driver entries')
+
+    def __str__(self):
+        return force_text(self.driver)
+
+    def get_attribute_count(self):
+        return self.entries.count()
+    get_attribute_count.short_description = _('Attribute count')
+
+
+class DocumentTypeSettings(models.Model):
+    """
+    Model to store the file metadata settings for a document type.
+    """
+    document_type = models.OneToOneField(
+        on_delete=models.CASCADE, related_name='file_metadata_settings',
+        to=DocumentType, unique=True, verbose_name=_('Document type')
+    )
+    auto_process = models.BooleanField(
+        default=True, verbose_name=_(
+            'Automatically queue newly created documents for processing.'
+        )
+    )
+
+    objects = DocumentTypeSettingsManager()
+
+    class Meta:
+        verbose_name = _('Document type settings')
+        verbose_name_plural = _('Document types settings')
+
+    def natural_key(self):
+        return self.document_type.natural_key()
+    natural_key.dependencies = ['documents.DocumentType']
+
+
+@python_2_unicode_compatible
+class FileMetadataEntry(models.Model):
+    document_version_driver_entry = models.ForeignKey(
+        related_name='entries', to=DocumentVersionDriverEntry,
+        verbose_name=_('Document version driver entry')
+    )
+
+    key = models.CharField(
+        db_index=True, help_text=_('Name of the file metadata entry.'),
+        max_length=255, verbose_name=_('Key')
+    )
+    value = models.CharField(
+        db_index=True, help_text=_('Value of the file metadata entry.'),
+        max_length=255, verbose_name=_('Value')
+    )
+
+    class Meta:
+        ordering = ('key', 'value')
+        verbose_name = _('File metadata entry')
+        verbose_name_plural = _('File metadata entries')
+
+    def __str__(self):
+        return '{}: {}: {}'.format(
+            self.document_version_driver_entry, self.key, self.value
+        )