add KnexNode.getDescendants

.gitignore

@@ -7,6 +7,8 @@ yarn-error.log*
 lerna-debug.log*
 .vscode
 
+src/test/test.ts
+
 # Diagnostic reports (https://nodejs.org/api/report.html)
 report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
 

README.md

@@ -125,6 +125,15 @@ const data = await node.getPathUpTo(7);
 // return the path from this node to the descendant(id = 7)
 const data = await node.getPathDownTo(7);
 ```
+##### `KnexNode.getDescendants(maxLevel?)` => `Promise<(Model & ITreeLv)[] | null>`
+```js
+// data is null if this.id doesn't exist
+// return all descendants
+let data = await node.getDescendants();
+
+// return all descendants whose TreeLv <= 2
+data = await node.getDescendants(2);
+```
 
 ## 🙋‍♂️ Author
 

src/index.ts

@@ -102,6 +102,7 @@ export class KnexNode<IdType, Model> implements INode<IdType, Model> {
   }
 
   async hasChild (id: IdType): Promise<Model | null> {
+    if (id === this.id) return null;
     const where: any = {};
     where[this.options.idColumn] = id;
     where[this.options.parentIdColumn] = this.id;
@@ -112,6 +113,7 @@ export class KnexNode<IdType, Model> implements INode<IdType, Model> {
   }
 
   async hasParent (id: IdType): Promise<Model | null> {
+    if (id === this.id) return null;
     const where: any = {};
     where[`n.${this.options.idColumn}`] = this.id;
     where[`p.${this.options.idColumn}`] = id;
@@ -178,4 +180,27 @@ export class KnexNode<IdType, Model> implements INode<IdType, Model> {
     });
     return result.reverse();
   }
+
+  async getDescendants (maxLevel?: number): Promise<(Model & ITreeLv)[] | null> {
+    const result = await this.options.db
+      .withRecursive('pt', (qb) => {
+        qb.select([ this.options.table + '.*', this.options.db.raw('0 as `TreeLv`') ])
+          .from(this.options.table)
+          .where(this.options.table + '.' + this.options.idColumn, this.id as unknown as string)
+          .union((qb) => {
+            qb.select([ 'p.*', this.options.db.raw('`TreeLv` + 1') ])
+              .from(this.options.db.raw('`' + this.options.table + '` as `p`, `pt` as `n`'))
+              .whereRaw('p.' + this.options.parentIdColumn + ' = n.' + this.options.idColumn)
+              .andWhereRaw('p.' + this.options.idColumn + ' != n.' + this.options.idColumn);
+            if (maxLevel)
+              qb.andWhere('n.TreeLv', '<', maxLevel);
+          });
+      })
+      .select('*').from('pt');
+
+    if (!result || result.length < 1)
+      return null;
+    result.shift();
+    return result;
+  }
 }

src/interface.ts

@@ -19,6 +19,8 @@ export interface INode<IdType, Model> {
 
   getPathUpTo(id: IdType, maxLevel?: number): Promise<(Model & ITreeLv)[] | null>;
   getPathDownTo(id: IdType, maxLevel?: number): Promise<(Model & ITreeLv)[] | null>;
+
+  getDescendants(maxLevel?: number): Promise<(Model & ITreeLv)[] | null>;
 }
 
 export interface ITree<IdType, Model> {