Dr. Sauce Posts - Answer Overflow

Dr. Sauce

•Created by Dr. Sauce on 7/7/2023 in #help

Type of query result is {}[]

Hi all! Loving using Kysely at the moment, it's super easy to use. I ran into one problem, which I believe is probably a lack of understanding from myself around certain elements of TypeScript or Kysely itself. Here is the DB Schema from kysely-codegen:

import type { ColumnType } from "kysely";

export type Generated<T> = T extends ColumnType<infer S, infer I, infer U>
  ? ColumnType<S, I | undefined, U>
  : ColumnType<T, T | undefined, T>;

export type Numeric = ColumnType<string, string | number, string | number>;

export type Timestamp = ColumnType<Date, Date | string, Date | string>;

export interface Disease {
  id: Generated<string>;
  coding_id: string;
  coding_id_string: string;
  description: string;
  created_at: Generated<Timestamp>;
  updated_at: Generated<Timestamp>;
}

export interface DiseaseTermSimilarity {
  id: Generated<string>;
  source_disease_id: string;
  target_disease_id: string;
  distance: Numeric;
  created_at: Generated<Timestamp>;
  updated_at: Generated<Timestamp>;
}

import type { ColumnType } from "kysely";

export type Generated<T> = T extends ColumnType<infer S, infer I, infer U>
  ? ColumnType<S, I | undefined, U>
  : ColumnType<T, T | undefined, T>;

export type Numeric = ColumnType<string, string | number, string | number>;

export type Timestamp = ColumnType<Date, Date | string, Date | string>;

export interface Disease {
  id: Generated<string>;
  coding_id: string;
  coding_id_string: string;
  description: string;
  created_at: Generated<Timestamp>;
  updated_at: Generated<Timestamp>;
}

export interface DiseaseTermSimilarity {
  id: Generated<string>;
  source_disease_id: string;
  target_disease_id: string;
  distance: Numeric;
  created_at: Generated<Timestamp>;
  updated_at: Generated<Timestamp>;
}

Here is a simplified version of a query (which is without any type errors). It also returns the results correctly from the DB:

  const query = db
    // Select all disease mappings
    .selectFrom('disease_term_similarity as mapping')
    // Append on the source disease's info by it's ID
    .leftJoin('disease as src_disease', (join) =>
      join.onRef('src_disease.id', '=', 'mapping.source_disease_id')
    )
    // Append on the target disease's info by it's ID
    .leftJoin('disease as tgt_disease', (join) =>
      join.onRef('tgt_disease.id', '=', 'mapping.target_disease_id')
    );

  const results = await query.execute();

  const query = db
    // Select all disease mappings
    .selectFrom('disease_term_similarity as mapping')
    // Append on the source disease's info by it's ID
    .leftJoin('disease as src_disease', (join) =>
      join.onRef('src_disease.id', '=', 'mapping.source_disease_id')
    )
    // Append on the target disease's info by it's ID
    .leftJoin('disease as tgt_disease', (join) =>
      join.onRef('tgt_disease.id', '=', 'mapping.target_disease_id')
    );

  const results = await query.execute();

I noticed that results has the type {}[]. I expected the result to be aware of what fields are contained in the returned objects. Is there something specific I need to do in order to have the results array typed? Or should I be casting it to a type I create myself? Many thanks for your help!!!

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