typeorm-pg-adjacency-list-tree

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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

Current version of the library is compatible with typeorm >= 0.3.0. If you use
typeorm < 0.3.0, please use typeorm-pg-adjacency-list-tree < 2.0.0.

Installation

``bash
npm i typeorm-pg-adjacency-list-tree
`

Quick start

$3

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

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

`typescript
@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:

`typescript
@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:

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

@TreeParent()
public parent!: Node

@TreeChildren()
public children!: Node[]

@Column()
public value!: number
}
`

$3

In the latest major version of typeorm, they decided to drop support for
creating custom repositories with classes. And now the only way to create a
custom repository is to call dataSource.getRepository(Entity).extend({ / your custom repo here / }).

To simplify the process of getting the tree repo, there's a helper function
extendTreeRepository.

If you have any suggestions on how to implement this in a better way, please
create an issue or send a pr.

Instantiating a tree repo from connection:
`typescript
import { extendTreeRepository } from 'typeorm-pg-adjacency-list-tree'

const nodeRepo = extendTreeRepository(dataSource.getRepository(Node))
const roots = await nodeRepo.findRoots()
`

After 0.3, extending a tree repo is not as simple as just extending a class.

We have to get our tree repository first.

`typescript
import { extendTreeRepository } from 'typeorm-pg-adjacency-list-tree'

const userRepo = extendTreeRepository(dataSource.getRepository(User)).extend({
async getByName(name: string) {
return this.find({ where: { name } })
},
})
`

$3

`typescript
findTrees(options?: FindTreeOptions): Promise
`

Gets complete trees for all roots in the table.

`typescript
findRoots(options?: FindTreeOptions): Promise
`

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

`typescript
findDescendants(entity: Entity, options?: FindTreeOptions): Promise
`

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

`typescript
findDescendantsTree(entity: Entity, options?: FindTreeOptions): Promise
`

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

`typescript
countDescendants(entity: Entity): Promise
`

Gets number of descendants of the entity.

`typescript
createDescendantsQueryBuilder(alias: string, entity: Entity): Promise>
`

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

`typescript
findAncestors(entity: Entity, options?: FindTreeOptions): Promise
`

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

`typescript
findAncestorsTree(entity: Entity, options?: FindTreeOptions): Promise
`

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

`typescript
countAncestors(entity: Entity): Promise
`

Gets number of ancestors of the entity.

`typescript
createAncestorsQueryBuilder(alias: string, entity: Entity): Promise>
``

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