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      • Tree collection

      Collection: TreeCommunity Edition+

      Introduction

      Tree collections are suitable for data with parent-child relationships, such as organizational structures, product categories, regional hierarchies, department directories, and knowledge-base directories. A Tree collection uses the adjacency-list model to store parent-child relationships, and each record can point to its own parent node.

      You can create Tree collections only from the main data source. External databases, REST API data sources, and External NocoBase data sources do not support creating Tree collections.

      Use cases

      Tree collections are suitable for these business scenarios:

      • Company organizational structures and department hierarchies
      • Product categories, knowledge-base directories, and document directories
      • Province, city, and district hierarchies; sales territories; and service-outlet hierarchies
      • BOM categories, equipment categories, and asset categories

      Create and configure

      In the main data source, click Create collection and select Tree collection to create a Tree collection.

      Create a Tree collection

      The creation settings for a Tree collection are mostly the same as those for a general collection.

      SettingDescription
      Collection display nameThe name displayed for the collection, such as Organization, Product categories, or Regional hierarchy.
      Collection nameThe collection identifier used internally by APIs, relation fields, permissions, and workflows.
      InheritsSelect a parent collection to inherit. This setting is visible only when the main database is PostgreSQL.
      CategoriesCollection categories affect only organization in Data source management; they do not change the collection structure.
      DescriptionA description of the collection. State which hierarchy data it stores, who maintains it, and which page filters use it.
      Preset fieldsPreset fields. Keep system fields and Tree collection built-in fields when creating a Tree collection.

      Built-in fields

      After a Tree collection is created, it usually includes the following built-in fields. parentId, parent, and children store the hierarchy.

      FieldField nameDescription
      IDidThe default primary key that uniquely identifies a record.
      Created atcreatedAtAutomatically records when the record was created.
      Created bycreatedByAutomatically records the user who created the record.
      Updated atupdatedAtAutomatically records when the record was last updated.
      Updated byupdatedByAutomatically records the user who last updated the record.
      Parent IDparentIdStores the parent-node ID. It is usually empty for root nodes.
      ParentparentA many-to-one relation field that points to a parent node in the current collection.
      ChildrenchildrenA one-to-many relation field representing child nodes of the current node.
      SpacespaceAvailable after enabling the Multi-space plugin. It isolates data by space and does not appear when Multi-space is not enabled.

      Tree collection built-in fields

      Note

      Avoid circular relationships in Tree collection data. For example, do not make B the parent of A and A the parent of B. Circular relationships cause incorrect tree displays and filter results.

      Primary key field

      Like a general collection, a Tree collection needs a primary key. Tree relation fields use the parent-node ID to relate to the primary-key record in the same collection.

      If a Tree collection has no primary key, set Record unique key when editing the collection. Otherwise, blocks might not view or edit records correctly, and tree displays might not locate nodes reliably.

      Use in pages

      A Tree collection can use most of the data blocks for a general collection to create, read, update, and delete records. It can also work with tree-specific features:

      BlockUse
      Table blockDisplays hierarchical records for viewing and maintaining parent-child structures.
      Form blockCreates or edits one Tree node record.
      Details blockViews details of one Tree node.
      Tree Filter blockFilters other data blocks with a tree structure. It is commonly used for category, organization, regional, and other hierarchical filters.

      Edit configuration

      In the collection list, click Edit next to a Tree collection to change its display name, category, description, simple pagination mode, Record unique key, and other settings.

      Do not delete Tree collection parent-child relation fields or repurpose them casually. To adjust the hierarchy, update parent-node relations in the record data first.

      Delete a collection

      In the collection list, click Delete next to a Tree collection to delete it.

      Deleting a Tree collection deletes its collection metadata, actual database table, and hierarchy data. Before deleting it, confirm whether page blocks, Tree Filter blocks, relation fields, permissions, workflows, or APIs still depend on it.

      Warning

      Tree collections are often used as filter conditions for other blocks. After deleting a Tree collection, related Tree Filter blocks and page configurations that depend on its category hierarchy might stop working.