# Django Treebeard

***

**1. Nested Hierarchies**

```python
class Category(models.Model):
    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
    name = models.CharField(max_length=255)
```

**2. Ancestor Queries**

```python
categories = Category.objects.get_descendants(root_category)
ancestors = Category.objects.get_ancestors(leaf_category)
```

**3. Level Ordering**

```python
categories = Category.objects.order_by('mptt_level')
```

**4. Tree Depth**

```python
max_depth = Category.objects.aggregate(Max('mptt_level'))['mptt_level__max']
```

**5. Tree Walk**

```python
for node in Category.objects.walk():
    print(node.name)
```

**6. Siblings**

```python
siblings = Category.objects.get_siblings(category)
```

**7. Cousins**

```python
cousins = Category.objects.get_cousins(category)
```

**8. Deleting Nodes**

```python
category.delete_with_descendants()
```

**9. Moving Nodes**

```python
new_parent = Category.objects.get(pk=1)
category.move_to(new_parent, 'right')
```

**10. Custom Tree Models**

```python
class CustomTree(models.Model):
    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
    name = models.CharField(max_length=255)

    treebeard.register(CustomTree, parent_attr='parent')
```

**11. Ancestor Query with Custom Tree**

```python
custom_tree_nodes = CustomTree.objects.get_descendants(root_node)
```

**12. In-Memory Tree**

```python
tree = Tree(Category.objects.all())
```

**13. Tree Distances**

```python
distance = Category.objects.get_distance_to_root_node(leaf_node)
```

**14. Tree Paths**

```python
path = Category.objects.get_path_to_root_node(leaf_node)
```

**15. Node Annotations**

```python
categories = Category.objects.annotate(num_posts=F('post_set__count'))
```

**16. Tree Selection**

```python
categories = Category.objects.get_children(parent).filter(name__startswith='A')
```

**17. Tree Serialization**

```python
serialized_tree = treebeard.serialize(Category.objects.all())
```

**18. Tree Deserialization**

```python
deserialized_tree = treebeard.deserialize(serialized_tree)
```

**19. Lazy Tree**

```python
tree = treebeard.LazyTree(Category.objects.all())
```

**20. Custom Tree Attributes**

```python
class CustomTree(models.Model):
    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
    name = models.CharField(max_length=255)
    custom_attr = models.IntegerField()

    treebeard.register(CustomTree, parent_attr='parent')
```

**21. Parentless Nodes**

```python
parentless_nodes = Category.objects.filter(parent__isnull=True)
```

**22. Tree Management**

```python
tree = treebeard.register(Category)
tree.invert()
tree.fix_foreign_keys()
```

**23. Tree Search**

```python
query = 'search term'
nodes = Category.objects.search(query)
```

**24. Tree Hierarchy Chart**

```python
tree_chart = treebeard.render_hierarchy_chart(Category.objects.all())
```

**25. Tree Web Interface**

```python
from treebeard.admin import TreeAdmin

class CategoryAdmin(TreeAdmin):
    pass

admin.site.register(Category, CategoryAdmin)
```

**26. Nested Tree Structure**

```python
class NestedCategory(models.Model):
    path = models.CharField(max_length=255)
    name = models.CharField(max_length=255)

    def __str__(self):
        return self.name
```

**27. Tree Navigation**

```python
current_node = Category.objects.get(pk=1)
siblings = current_node.get_siblings()
parent = current_node.get_parent()
```

**28. Tree Management Signals**

```python
treebeard.register(Category)

@receiver(post_save, sender=Category)
def update_mptt_fields(sender, instance, **kwargs):
    instance.update_mptt_fields()
```

**29. Tree RichText**

```python
from treebeard import admin as treebeard_admin

class RichTextAdmin(treebeard_admin.TreeAdmin):
    pass

admin.site.register(Category, RichTextAdmin)
```

**30. Tree Customization**

```python
treebeard.register(Category, parent_attr='parent_id', tree_attr='parent_path')
```

**31. Tree Permissions**

```python
from django.contrib.auth.models import Permission

permission = Permission.objects.get(codename='view_category')
category.set_permission(permission, user)
```

**32. Tree Templates**

```html

<div data-gb-custom-block data-tag="tree_node"></div>

{{ node.name }}

<div data-gb-custom-block data-tag="tree_node_children"></div>

<div data-gb-custom-block data-tag="tree_node_end"></div>
```

**33. Tree Serialization Using UUID**

```python
data = treebeard.serialize(Category.objects.all(), format='json', uuid_field='uuid')
```

**34. Tree with Ordering**

```python
class OrderedCategory(models.Model):
    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
    name = models.CharField(max_length=255)
    order = models.PositiveIntegerField(default=0)

    treebeard.register(OrderedCategory, parent_attr='parent')
```

**35. Tree Soft Delete**

```python
from django_treebeard_softdelete import models as treebeard_softdelete

class SoftDeleteCategory(treebeard_softdelete.SoftDeleteModel, models.Model):
    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
    name = models.CharField(max_length=255)
```

**36. Tree with Self-Referencing Foreign Key**

```python
class SelfReferencingCategory(models.Model):
    category = models.ForeignKey('self', blank=True, null=True, related_name='subcategories')
    name = models.CharField(max_length=255)

    treebeard.register(SelfReferencingCategory, parent_attr='category')
```