typeorm-pg-adjacency-list-tree

This library helps to manage trees that are structured as as adjacency list in postgres.

It partially implements public interface of TreeRepository from typeorm. Check tree-repository.interface.ts

Installation

npm i typeorm-pg-adjacency-list-tree

Quick start

Decorators

There are three decorators exported from this module: Tree, TreeParent and TreeChildren.

Tree is used to specify that decoratable entity is a tree.

@Tree()
@Entity()
export class Node {
  @PrimaryGeneratedColumn()
  public id!: number

  @Column()
  public value!: number
}

TreeParent is used to identify class property which will hold entities parent:

@Tree()
@Entity()
export class Node {
  @PrimaryGeneratedColumn()
  public id!: number

  @TreeParent()
  public parent!: Node

  @Column()
  public value!: number
}

TreeChildren is used to identify class property which will hold children of current entity:

@Tree()
@Entity()
export class Node {
  @PrimaryGeneratedColumn()
  public id!: number

  @TreeParent()
  public parent!: Node

  @TreeChildren()
  public children!: Node[]

  @Column()
  public value!: number
}

Tree repository

TreeRepository can be used to access some methods used for working with trees:

// node-repository.ts

@EntityRepository(Node)
class NodeRepository extends TreeRepository<Node> {}

// node-service.ts
class NodeService {
  private _nodeRepo = getConnection().getCustomRepository(NodeRepository)

  public getAllTrees() {
    return this._nodeRepo.findTrees()
  }
}

Tree repository methods

public findTrees(options?: FindTreeOptions): Promise<Entity[]>

Gets complete trees for all roots in the table.

public findRoots(options?: FindTreeOptions): Promise<Entity[]>

Roots are entities that have no ancestors. Finds them all.

public findDescendants(entity: Entity, options?: FindTreeOptions): Promise<Entity[]>

Gets all children (descendants) of the given entity. Returns them all in a flat array.

public findDescendantsTree(entity: Entity, options?: FindTreeOptions): Promise<Entity>

Gets all children (descendants) of the given entity. Returns them in a tree - nested into each other.

public countDescendants(entity: Entity): Promise<number>

Gets number of descendants of the entity.

public createDescendantsQueryBuilder(alias: string, entity: Entity): Promise<SelectQueryBuilder<Entity>>

Creates a query builder used to get descendants of the entities in a tree.

public findAncestors(entity: Entity, options?: FindTreeOptions): Promise<Entity[]>

Creates a query builder used to get descendants of the entities in a tree.

public findAncestorsTree(entity: Entity, options?: FindTreeOptions): Promise<Entity>

Gets all parents (ancestors) of the given entity. Returns them in a tree - nested into each other.

public countAncestors(entity: Entity): Promise<number>

Gets number of ancestors of the entity.

public createAncestorsQueryBuilder(alias: string, entity: Entity): Promise<SelectQueryBuilder<Entity>>

Creates a query builder used to get ancestors of the entities in the tree.