Kysely•2y ago

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!!!

Solution:

It looks like the reassignment of query to itself was causing the issue. If I do something like this, the end result has the correct typing: ``` let queryBuilder; ...

Jump to solution

7 Replies

Unknown User•2y ago

Message Not Public

Dr. SauceOP•2y ago

Hey @valtyrorn apologies, I made a mistake in simplifying my query for the example above. I edited the post to include that part. The query is all working and returning results sucessfully Oh no, my message was too long 🙂 Here it is:

  let 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')
    );

  query = query.select([
    /** Mapping */
    'mapping.id',
    'mapping.distance',
    'mapping.created_at',
    'mapping.updated_at',
    /** Source disease */
    'src_disease.id as src_disease_id',
    'src_disease.coding_id as src_disease_coding_id',
    'src_disease.coding_id_string as src_disease_coding_id_string',
    /** Target disease */
    'tgt_disease.id as tgt_disease_id',
    'tgt_disease.coding_id as tgt_disease_coding_id',
    'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
  ]);

  const results = await query.execute();

  let 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')
    );

  query = query.select([
    /** Mapping */
    'mapping.id',
    'mapping.distance',
    'mapping.created_at',
    'mapping.updated_at',
    /** Source disease */
    'src_disease.id as src_disease_id',
    'src_disease.coding_id as src_disease_coding_id',
    'src_disease.coding_id_string as src_disease_coding_id_string',
    /** Target disease */
    'tgt_disease.id as tgt_disease_id',
    'tgt_disease.coding_id as tgt_disease_coding_id',
    'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
  ]);

  const results = await query.execute();

Solution

Dr. Sauce•2y ago

It looks like the reassignment of query to itself was causing the issue. If I do something like this, the end result has the correct typing:

  let queryBuilder;

  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')
    );

  queryBuilder = query.select([
    /** Mapping */
    'mapping.id',
    'mapping.distance',
    'mapping.created_at',
    'mapping.updated_at',
    /** Source disease */
    'src_disease.id as src_disease_id',
    'src_disease.coding_id as src_disease_coding_id',
    'src_disease.coding_id_string as src_disease_coding_id_string',
    /** Target disease */
    'tgt_disease.id as tgt_disease_id',
    'tgt_disease.coding_id as tgt_disease_coding_id',
    'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
  ]);

  const results = await queryBuilder.execute();

  let queryBuilder;

  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')
    );

  queryBuilder = query.select([
    /** Mapping */
    'mapping.id',
    'mapping.distance',
    'mapping.created_at',
    'mapping.updated_at',
    /** Source disease */
    'src_disease.id as src_disease_id',
    'src_disease.coding_id as src_disease_coding_id',
    'src_disease.coding_id_string as src_disease_coding_id_string',
    /** Target disease */
    'tgt_disease.id as tgt_disease_id',
    'tgt_disease.coding_id as tgt_disease_coding_id',
    'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
  ]);

  const results = await queryBuilder.execute();

The above example is slightly contrived. The reason I am using multiple statements to build the query rather than all in one block is because I have several if conditions for which certain parts of the query should or should not be included.

koskimas•2y ago

Type of a variable can't change. Reassignments after selects, joins and other method calls that change the query builder type can't work.

Dr. SauceOP•2y ago

Thanks @koskimas what's the best way to add a conditional call onto the query chain? For example, if only in specific cases I want to add an .orderBy call

koskimas•2y ago

Only joins, selections and returning method change the type. Others can be reassigned.

Dr. SauceOP•2y ago

I see, so the issue was the line:

query = query.select([
...

query = query.select([
...

Thank you so much for clarifying! Can confirm both of these work 🙂 Thank you! Makes sense now

let queryBuilder;

  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')
    )
    .select([
      /** Mapping */
      'mapping.id',
      'mapping.distance',
      'mapping.created_at',
      'mapping.updated_at',
      /** Source disease */
      'src_disease.id as src_disease_id',
      'src_disease.coding_id as src_disease_coding_id',
      'src_disease.coding_id_string as src_disease_coding_id_string',
      /** Target disease */
      'tgt_disease.id as tgt_disease_id',
      'tgt_disease.coding_id as tgt_disease_coding_id',
      'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
    ]);

  const results = await query.execute();

let queryBuilder;

  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')
    )
    .select([
      /** Mapping */
      'mapping.id',
      'mapping.distance',
      'mapping.created_at',
      'mapping.updated_at',
      /** Source disease */
      'src_disease.id as src_disease_id',
      'src_disease.coding_id as src_disease_coding_id',
      'src_disease.coding_id_string as src_disease_coding_id_string',
      /** Target disease */
      'tgt_disease.id as tgt_disease_id',
      'tgt_disease.coding_id as tgt_disease_coding_id',
      'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
    ]);

  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 queryWithSelect = query.select([
    /** Mapping */
    'mapping.id',
    'mapping.distance',
    'mapping.created_at',
    'mapping.updated_at',
    /** Source disease */
    'src_disease.id as src_disease_id',
    'src_disease.coding_id as src_disease_coding_id',
    'src_disease.coding_id_string as src_disease_coding_id_string',
    /** Target disease */
    'tgt_disease.id as tgt_disease_id',
    'tgt_disease.coding_id as tgt_disease_coding_id',
    'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
  ]);

  const results = await queryWithSelect.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 queryWithSelect = query.select([
    /** Mapping */
    'mapping.id',
    'mapping.distance',
    'mapping.created_at',
    'mapping.updated_at',
    /** Source disease */
    'src_disease.id as src_disease_id',
    'src_disease.coding_id as src_disease_coding_id',
    'src_disease.coding_id_string as src_disease_coding_id_string',
    /** Target disease */
    'tgt_disease.id as tgt_disease_id',
    'tgt_disease.coding_id as tgt_disease_coding_id',
    'tgt_disease.coding_id_string as tgt_disease_coding_id_string'
  ]);

  const results = await queryWithSelect.execute();

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Type of query result is {}[]

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