@nivinjoseph/n-data/src/db/query-result.ts

Data access library for Postgres based on Knex

/* eslint-disable @typescript-eslint/no-unsafe-call */
import { given } from "@nivinjoseph/n-defensive";
// @ts-expect-error: no types
import Treeize from "treeize";

/**
 * Represents the result of a database query.
 * Provides methods to access and transform the query results.
 * 
 * @class QueryResult
 * @template T - The type of the rows in the result
 */
export class QueryResult<T>
{
    private readonly _rows: Array<T>;

    /**
     * Gets the rows returned by the query.
     * 
     * @readonly
     * @type {ReadonlyArray<T>}
     */
    public get rows(): ReadonlyArray<T> { return this._rows; }


    public constructor(rows: Array<T>)
    {
        given(rows, "rows").ensureHasValue().ensureIsArray();
        this._rows = rows;
    }

    /**
     * Transforms the flat result rows into a tree structure.
     * Useful for converting database results with parent-child relationships into nested objects.
     * 
     * @template U - The type of the transformed result
     * @returns {Array<U>} The transformed result as a tree structure
     */
    public toObjectTree<U>(): Array<U>
    {
        const tree = new Treeize();
        tree.grow(this._rows);
        return tree.getData() as Array<U>;
    }
}