K
Kyselyā€¢17mo ago
cheekybuddha

Typescript Error when creating MySQL db pool

Hi Everyone, I'm getting the following error when creating a database: 
kysely Type '() => Promise<Pool>' is not assignable to type 'MysqlPool | (() => Promise<MysqlPool>)'
kysely Type '() => Promise<Pool>' is not assignable to type 'MysqlPool | (() => Promise<MysqlPool>)'
I'm using the following code: 
// db.ts
import {
  Kysely,
  MysqlDialect,
}                     from 'kysely'
import { createPool } from 'mysql2'
import {
  DB_HOST,
  DB_PORT,
  DB_USER,
  DB_PASS,
  DB_NAME
}                     from '$env/static/private'
import type { DB }    from 'kysely-codegen'

export const mysqlPoolOpts = {
  database:           DB_NAME,
  host:               DB_HOST,
  port:               parseInt(DB_PORT),
  user:               DB_USER,
  password:           DB_PASS,
  waitForConnections: true,
  connectionLimit:    10,
  // maxIdle:            10, // max idle connections, the default value is the same as `connectionLimit`
  // idleTimeout:        60000, // idle connections timeout, in milliseconds, the default value 60000
  queueLimit:         0
}

export const db = new Kysely<DB>({
  dialect: new MysqlDialect({
    pool: async () => createPool(mysqlPoolOpts)
//   ^^ -- error here
  })
})
// db.ts
import {
  Kysely,
  MysqlDialect,
}                     from 'kysely'
import { createPool } from 'mysql2'
import {
  DB_HOST,
  DB_PORT,
  DB_USER,
  DB_PASS,
  DB_NAME
}                     from '$env/static/private'
import type { DB }    from 'kysely-codegen'

export const mysqlPoolOpts = {
  database:           DB_NAME,
  host:               DB_HOST,
  port:               parseInt(DB_PORT),
  user:               DB_USER,
  password:           DB_PASS,
  waitForConnections: true,
  connectionLimit:    10,
  // maxIdle:            10, // max idle connections, the default value is the same as `connectionLimit`
  // idleTimeout:        60000, // idle connections timeout, in milliseconds, the default value 60000
  queueLimit:         0
}

export const db = new Kysely<DB>({
  dialect: new MysqlDialect({
    pool: async () => createPool(mysqlPoolOpts)
//   ^^ -- error here
  })
})
(cont'd in following message ...)
11 Replies
cheekybuddha
cheekybuddhaOPā€¢17mo ago
My dependencies are: 
$ pnpm ls --depth=0
Legend: production dependency, optional only, dev only

[email protected] /home/dm/Documents/websites/thdt_admin (PRIVATE)

dependencies:
@lucia-auth/adapter-mysql 2.0.0
kysely 0.26.1
lucia 2.0.0
mysql2 3.6.0

devDependencies:
@csstools/postcss-global-data 2.0.1      eslint 8.46.0                            postcss-preset-env 9.1.1                 sveltekit-superforms 1.5.0               
@sveltejs/adapter-auto 2.1.0             eslint-config-prettier 8.10.0            prettier 3.0.1                           tslib 2.6.1                              
@sveltejs/kit 1.22.4                     eslint-plugin-svelte 2.32.4              prettier-plugin-svelte 3.0.3             typescript 5.1.6                         
@typescript-eslint/eslint-plugin 5.62.0  kysely-codegen 0.10.1                    svelte 4.1.2                             vite 4.4.9                               
@typescript-eslint/parser 5.62.0         postcss 8.4.27                           svelte-check 3.4.6                       zod 3.21.4                               
autoprefixer 10.4.14                     postcss-csso 6.0.1                       svelte-preprocess 5.0.4
$ pnpm ls --depth=0
Legend: production dependency, optional only, dev only

[email protected] /home/dm/Documents/websites/thdt_admin (PRIVATE)

dependencies:
@lucia-auth/adapter-mysql 2.0.0
kysely 0.26.1
lucia 2.0.0
mysql2 3.6.0

devDependencies:
@csstools/postcss-global-data 2.0.1      eslint 8.46.0                            postcss-preset-env 9.1.1                 sveltekit-superforms 1.5.0               
@sveltejs/adapter-auto 2.1.0             eslint-config-prettier 8.10.0            prettier 3.0.1                           tslib 2.6.1                              
@sveltejs/kit 1.22.4                     eslint-plugin-svelte 2.32.4              prettier-plugin-svelte 3.0.3             typescript 5.1.6                         
@typescript-eslint/eslint-plugin 5.62.0  kysely-codegen 0.10.1                    svelte 4.1.2                             vite 4.4.9                               
@typescript-eslint/parser 5.62.0         postcss 8.4.27                           svelte-check 3.4.6                       zod 3.21.4                               
autoprefixer 10.4.14                     postcss-csso 6.0.1                       svelte-preprocess 5.0.4
I created the DB types using kysely-codegen: 
$ npx kysely-codegen
ā€¢ Loaded environment variables from .env file.
ā€¢ No dialect specified. Assuming 'mysql'.
ā€¢ Introspecting database...
āœ“ Introspected 29 tables and generated ./node_modules/kysely-codegen/dist/db.d.ts in 408ms.
$ npx kysely-codegen
ā€¢ Loaded environment variables from .env file.
ā€¢ No dialect specified. Assuming 'mysql'.
ā€¢ Introspecting database...
āœ“ Introspected 29 tables and generated ./node_modules/kysely-codegen/dist/db.d.ts in 408ms.
I'm still very new with typescript - how can I get the type MysqlPool to map to Pool ? Or am I doing something else wrong? TIA for any assistance, d
Igal
Igalā€¢17mo ago
Hey šŸ‘‹ Can you share your tsconfig.json? can you share the entire typescript error?
cheekybuddha
cheekybuddhaOPā€¢17mo ago
Sure! 
// tsconfig.json
{
    "extends": "./.svelte-kit/tsconfig.json",
    "compilerOptions": {
        "allowJs": true,
        "checkJs": true,
        "esModuleInterop": true,
        "forceConsistentCasingInFileNames": true,
        "resolveJsonModule": true,
        "skipLibCheck": true,
        "sourceMap": true,
        "strict": true
    }
    // Path aliases are handled by https://kit.svelte.dev/docs/configuration#alias
    //
    // If you want to overwrite includes/excludes, make sure to copy over the relevant includes/excludes
    // from the referenced tsconfig.json - TypeScript does not merge them in
}
// tsconfig.json
{
    "extends": "./.svelte-kit/tsconfig.json",
    "compilerOptions": {
        "allowJs": true,
        "checkJs": true,
        "esModuleInterop": true,
        "forceConsistentCasingInFileNames": true,
        "resolveJsonModule": true,
        "skipLibCheck": true,
        "sourceMap": true,
        "strict": true
    }
    // Path aliases are handled by https://kit.svelte.dev/docs/configuration#alias
    //
    // If you want to overwrite includes/excludes, make sure to copy over the relevant includes/excludes
    // from the referenced tsconfig.json - TypeScript does not merge them in
}
Full error: 
Type '() => Promise<Pool>' is not assignable to type 'MysqlPool | (() => Promise<MysqlPool>)'.
  Type '() => Promise<Pool>' is not assignable to type '() => Promise<MysqlPool>'.
    Type 'Promise<Pool>' is not assignable to type 'Promise<MysqlPool>'.
      Type 'Pool' is not assignable to type 'MysqlPool'.
        Types of property 'getConnection' are incompatible.
          Type '(callback: (err: any, connection: PoolConnection) => any) => void' is not assignable to type '(callback: (error: unknown, connection: MysqlPoolConnection) => void) => void'.
            Types of parameters 'callback' and 'callback' are incompatible.
              Types of parameters 'connection' and 'connection' are incompatible.
                Property 'query' is missing in type 'PoolConnection' but required in type 'MysqlPoolConnection'.ts(2322)
mysql-dialect-config.d.ts(34, 5): 'query' is declared here.
mysql-dialect-config.d.ts(15, 5): The expected type comes from property 'pool' which is declared here on type 'MysqlDialectConfig'
(property) MysqlDialectConfig.pool: MysqlPool | (() => Promise<MysqlPool>)
A mysql2 Pool instance or a function that returns one.

If a function is provided, it's called once when the first query is executed.

https://github.com/sidorares/node-mysql2#using-connection-pools
Type '() => Promise<Pool>' is not assignable to type 'MysqlPool | (() => Promise<MysqlPool>)'.
  Type '() => Promise<Pool>' is not assignable to type '() => Promise<MysqlPool>'.
    Type 'Promise<Pool>' is not assignable to type 'Promise<MysqlPool>'.
      Type 'Pool' is not assignable to type 'MysqlPool'.
        Types of property 'getConnection' are incompatible.
          Type '(callback: (err: any, connection: PoolConnection) => any) => void' is not assignable to type '(callback: (error: unknown, connection: MysqlPoolConnection) => void) => void'.
            Types of parameters 'callback' and 'callback' are incompatible.
              Types of parameters 'connection' and 'connection' are incompatible.
                Property 'query' is missing in type 'PoolConnection' but required in type 'MysqlPoolConnection'.ts(2322)
mysql-dialect-config.d.ts(34, 5): 'query' is declared here.
mysql-dialect-config.d.ts(15, 5): The expected type comes from property 'pool' which is declared here on type 'MysqlDialectConfig'
(property) MysqlDialectConfig.pool: MysqlPool | (() => Promise<MysqlPool>)
A mysql2 Pool instance or a function that returns one.

If a function is provided, it's called once when the first query is executed.

https://github.com/sidorares/node-mysql2#using-connection-pools
// ./.svelte-kit/tsconfig.json
{
    "compilerOptions": {
        "paths": {
            "$lib": [
                "../src/lib"
            ],
            "$lib/*": [
                "../src/lib/*"
            ]
        },
        "rootDirs": [
            "..",
            "./types"
        ],
        "importsNotUsedAsValues": "error",
        "isolatedModules": true,
        "preserveValueImports": true,
        "lib": [
            "esnext",
            "DOM",
            "DOM.Iterable"
        ],
        "moduleResolution": "node",
        "module": "esnext",
        "target": "esnext",
        "ignoreDeprecations": "5.0"
    },
    "include": [
        "ambient.d.ts",
        "./types/**/$types.d.ts",
        "../vite.config.ts",
        "../src/**/*.js",
        "../src/**/*.ts",
        "../src/**/*.svelte",
        "../tests/**/*.js",
        "../tests/**/*.ts",
        "../tests/**/*.svelte"
    ],
    "exclude": [
        "../node_modules/**",
        "./[!ambient.d.ts]**",
        "../src/service-worker.js",
        "../src/service-worker.ts",
        "../src/service-worker.d.ts"
    ]
}
// ./.svelte-kit/tsconfig.json
{
    "compilerOptions": {
        "paths": {
            "$lib": [
                "../src/lib"
            ],
            "$lib/*": [
                "../src/lib/*"
            ]
        },
        "rootDirs": [
            "..",
            "./types"
        ],
        "importsNotUsedAsValues": "error",
        "isolatedModules": true,
        "preserveValueImports": true,
        "lib": [
            "esnext",
            "DOM",
            "DOM.Iterable"
        ],
        "moduleResolution": "node",
        "module": "esnext",
        "target": "esnext",
        "ignoreDeprecations": "5.0"
    },
    "include": [
        "ambient.d.ts",
        "./types/**/$types.d.ts",
        "../vite.config.ts",
        "../src/**/*.js",
        "../src/**/*.ts",
        "../src/**/*.svelte",
        "../tests/**/*.js",
        "../tests/**/*.ts",
        "../tests/**/*.svelte"
    ],
    "exclude": [
        "../node_modules/**",
        "./[!ambient.d.ts]**",
        "../src/service-worker.js",
        "../src/service-worker.ts",
        "../src/service-worker.d.ts"
    ]
}
cheekybuddha
cheekybuddhaOPā€¢17mo ago
Don't you love it when you search for the solution to a problem for a couple of days and find the answer immediately after posting asking for assistance!! šŸ˜– šŸ˜³ I have found the answer here: https://lucia-auth.com/guidebook/kysely Turns out that createPool() does not return the pool - you have to access its pool property: 
export const db = new Kysely<DB>({
  dialect: new MysqlDialect({
    pool: async () => createPool(mysqlPoolOpts).pool
//                                             ^^^^^ reference .pool here!!!
  })
})
export const db = new Kysely<DB>({
  dialect: new MysqlDialect({
    pool: async () => createPool(mysqlPoolOpts).pool
//                                             ^^^^^ reference .pool here!!!
  })
})
Thanks for looking in šŸ‘
Lucia
Using Kysely
Igal
Igalā€¢17mo ago
hmm mysql2 might have introduced a breaking change there need to investigate
cheekybuddha
cheekybuddhaOPā€¢17mo ago
OK, keep us posted - will be interesting to see what you discover. Thanks for this, and Kysely!! šŸ‘ Actually, something is strange - returning .pool gets rid of the error, but it is not listed as a property in the intellisense. Like I said, I'm still new to typescript, so I don't know whether this is expected. Tried to add screenshots, but it failed. Will try again later.
Igal
Igalā€¢17mo ago
thank @koskimas šŸ‘ˆšŸ»
Igal
Igalā€¢17mo ago
Your example doesn't error in TypeScript playground https://tsplay.dev/w8659m
TS Playground - An online editor for exploring TypeScript and JavaS...
The Playground lets you write TypeScript or JavaScript online in a safe and sharable way.
Igal
Igalā€¢17mo ago
I have a feeling svelte kit not having skipLibCheck: true in its tsconfig.json causes this They are breaking things after a LOT of time of inactivity over at mysql2
Igal
Igalā€¢17mo ago
Igal
Igalā€¢17mo ago
https://github.com/sidorares/node-mysql2/pull/2087/files#diff-060fa38f61c034c79cb5a1181100b2be6573abd6df6b3b06481b8d7b714199e0 -> https://github.com/sidorares/node-mysql2/pull/2087/files#diff-dc79f011c56f6ff43dbd4a64f19a61cf0be81b265aacdc22484dc9cb366c6dbf might have broken this
GitHub
fix: change from .ts files to .d.ts by wellwelwel Ā· Pull Request #2...
See: #2086 reproduce error from #2086 reproduce error from sveltejs/language-tools#2068 resolve new conflicts on current tests add these errors to CI Test create declarations for: .../Ex...
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