snippeteer/lib/snippets/database/patch_actions/RenameColumn.ts

import { Serializable } from '../classes/Serializable';
import { PatchAction } from '../classes/PatchAction';
import { Database } from '../classes/Database';

export class RenameColumn implements Serializable, PatchAction {
  public table: string;
  public column: string;
  public new_name: string;

  public constructor (
    column: string,
    new_name: string|null = null,
    table: string|null = null
  ) {
    if (new_name === null || table === null) {
      const regex
      = /(?<table>[a-z_]+) (?<column>[a-z_]+) (?<new_name>[a-z_]+)/iu;
      const res = regex.exec (column);
      if (res === null || typeof res.groups === 'undefined')
        throw new Error ('invalid string to deserialize');

      this.column = res.groups.column;
      this.new_name = res.groups.new_name;
      this.table = res.groups.table;
      return;
    }

    this.column = column;
    this.table = table;
    this.new_name = new_name;
  }

  public serialize (): string {
    return `${this.table} ${this.column} ${this.new_name}`;
  }

  public apply (db: Database): void {
    const table = db.get_table (this.table);
    if (typeof table === 'undefined' || table === null) {
      throw new Error (
        `table ${this.table} not found`
      );
    }
    const column = table.get_column (this.column);
    if (typeof column === 'undefined' || column === null) {
      throw new Error (
        `column ${this.column} not found in table ${this.table}`
      );
    }

    column.name = this.new_name;
  }
}