Change strategy for creating database

Use 'ensureDatabaseExists' flag on the migrate function.

I _think_ this makes the API smaller/simpler.

This implementation also checks whether the database exists before
trying to create it, which means it _should_ work on readonly
replicas.

Fixes #57

Author: ThomWright

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## 5.3.0
+
+- [DEPRECATION] Deprecate `createDb`
+- Add `ensureDatabaseExists` to check/create database in `migrate`
+
 ## 5.1.0
 
 - Validate migration ordering when loading files (instead of when applying migrations)

README.md

@@ -27,7 +27,7 @@ There are two ways to use the API.
 Either, pass a database connection config object:
 
 ```typescript
-import {createDb, migrate} from "postgres-migrations"
+import {migrate} from "postgres-migrations"
 
 async function() {
   const dbConfig = {
@@ -36,20 +36,24 @@ async function() {
     password: "password",
     host: "localhost",
     port: 5432,
+
+    // Default: false for backwards-compatibility
+    // This might change!
+    ensureDatabaseExists: true
+
+    // Default: "postgres"
+    // Used when checking/creating "database-name"
+    defaultDatabase: "postgres"
   }
 
-  await createDb(databaseName, {
-    ...dbConfig,
-    defaultDatabase: "postgres", // defaults to "postgres"
-  })
   await migrate(dbConfig, "path/to/migration/files")
 }
 ```
 
 Or, pass a `pg` client:
 
 ```typescript
-import {createDb, migrate} from "postgres-migrations"
+import {migrate} from "postgres-migrations"
 
 async function() {
   const dbConfig = {
@@ -60,27 +64,13 @@ async function() {
     port: 5432,
   }
 
-  {
-    const client = new pg.Client({
-      ...dbConfig,
-      database: "postgres",
-    })
-    await client.connect()
-    try {
-      await createDb(databaseName, {client})
-    } finally {
-      await client.end()
-    }
-  }
-
-  {
-    const client = new pg.Client(dbConfig) // or a Pool, or a PoolClient
-    await client.connect()
-    try {
-      await migrate({client}, "path/to/migration/files")
-    } finally {
-      await client.end()
-    }
+  // Note: when passing a client, it is assumed that the database already exists
+  const client = new pg.Client(dbConfig) // or a Pool, or a PoolClient
+  await client.connect()
+  try {
+    await migrate({client}, "path/to/migration/files")
+  } finally {
+    await client.end()
   }
 }
 ```
@@ -251,10 +241,10 @@ If you want sane date handling, it is recommended you use the following code sni
 ```js
 const pg = require("pg")
 
-const parseDate = val =>
+const parseDate = (val) =>
   val === null ? null : moment(val).format("YYYY-MM-DD")
 const DATATYPE_DATE = 1082
-pg.types.setTypeParser(DATATYPE_DATE, val => {
+pg.types.setTypeParser(DATATYPE_DATE, (val) => {
   return val === null ? null : parseDate(val)
 })
 ```

src/__tests__/fixtures/ensure-exists/1_success.sql

@@ -0,0 +1,3 @@
+CREATE TABLE success (
+  id integer
+);

src/__tests__/migrate.ts

@@ -2,7 +2,7 @@
 import test from "ava"
 import * as pg from "pg"
 import SQL from "sql-template-strings"
-import {createDb, migrate} from "../"
+import {createDb, migrate, MigrateDBConfig} from "../"
 import {PASSWORD, startPostgres, stopPostgres} from "./fixtures/docker-postgres"
 
 const CONTAINER_NAME = "pg-migrations-test-migrate"
@@ -384,7 +384,7 @@ test("bad arguments - incorrect port", (t) => {
     })
 })
 
-test("no database", (t) => {
+test("no database - ensureDatabaseExists = undefined", (t) => {
   return t
     .throwsAsync(
       migrate(
@@ -406,6 +406,65 @@ test("no database", (t) => {
     })
 })
 
+test("no database - ensureDatabaseExists = true", (t) => {
+  const databaseName = "migration-test-no-db-ensure-exists"
+  const dbConfig: MigrateDBConfig = {
+    database: databaseName,
+    user: "postgres",
+    password: PASSWORD,
+    host: "localhost",
+    port,
+
+    ensureDatabaseExists: true,
+  }
+
+  return migrate(dbConfig, "src/__tests__/fixtures/ensure-exists")
+    .then(() => doesTableExist(dbConfig, "success"))
+    .then((exists) => {
+      t.truthy(exists)
+    })
+})
+
+test("existing database - ensureDatabaseExists = true", (t) => {
+  const databaseName = "migration-test-existing-db-ensure-exists"
+  const dbConfig: MigrateDBConfig = {
+    database: databaseName,
+    user: "postgres",
+    password: PASSWORD,
+    host: "localhost",
+    port,
+
+    ensureDatabaseExists: true,
+  }
+
+  return createDb(databaseName, dbConfig)
+    .then(() => migrate(dbConfig, "src/__tests__/fixtures/ensure-exists"))
+    .then(() => doesTableExist(dbConfig, "success"))
+    .then((exists) => {
+      t.truthy(exists)
+    })
+})
+
+test("no database - ensureDatabaseExists = true, bad default database", (t) => {
+  const databaseName = "migration-test-ensure-exists-nope"
+  const dbConfig: MigrateDBConfig = {
+    database: databaseName,
+    user: "postgres",
+    password: PASSWORD,
+    host: "localhost",
+    port,
+
+    ensureDatabaseExists: true,
+    defaultDatabase: "nopenopenope",
+  }
+
+  return t
+    .throwsAsync(migrate(dbConfig, "src/__tests__/fixtures/ensure-exists"))
+    .then((err) => {
+      t.regex(err.message, /database "nopenopenope" does not exist/)
+    })
+})
+
 test("no migrations dir", (t) => {
   const databaseName = "migration-test-no-dir"
   const dbConfig = {

src/create.ts

@@ -4,6 +4,9 @@ import {withConnection} from "./with-connection"
 
 const DUPLICATE_DATABASE = "42P04"
 
+/**
+ * @deprecated Use `migrate` instead with `ensureDatabaseExists: true`.
+ */
 export async function createDb(
   dbName: string,
   dbConfig: CreateDBConfig,
@@ -25,7 +28,7 @@ export async function createDb(
   }
 
   if ("client" in dbConfig) {
-    return betterCreate(dbName, log)(dbConfig.client)
+    return runCreateQuery(dbName, log)(dbConfig.client)
   }
 
   if (
@@ -50,12 +53,12 @@ export async function createDb(
     log(`pg client emitted an error: ${err.message}`)
   })
 
-  const runWith = withConnection(log, betterCreate(dbName, log))
+  const runWith = withConnection(log, runCreateQuery(dbName, log))
 
   return runWith(client)
 }
 
-function betterCreate(dbName: string, log: Logger) {
+export function runCreateQuery(dbName: string, log: Logger) {
   return async (client: BasicPgClient): Promise<void> => {
     await client
       .query(`CREATE DATABASE "${dbName.replace(/\"/g, '""')}"`)

src/migrate.ts

@@ -1,5 +1,6 @@
 import * as pg from "pg"
 import SQL from "sql-template-strings"
+import {runCreateQuery} from "./create"
 import {loadMigrationFiles} from "./files-loader"
 import {runMigration} from "./run-migration"
 import {
@@ -14,6 +15,17 @@ import {validateMigrationHashes} from "./validation"
 import {withConnection} from "./with-connection"
 import {withAdvisoryLock} from "./with-lock"
 
+/**
+ * Run the migrations.
+ *
+ * If `dbConfig.ensureDatabaseExists` is true then `dbConfig.database` will be created if it
+ * does not exist.
+ *
+ * @param dbConfig Details about how to connect to the database
+ * @param migrationsDirectory Directory containing the SQL migration files
+ * @param config Extra configuration
+ * @returns Details about the migrations which were run
+ */
 export async function migrate(
   dbConfig: MigrateDBConfig,
   migrationsDirectory: string,
@@ -53,17 +65,45 @@ export async function migrate(
     throw new Error("Database config problem")
   }
 
-  const client = new pg.Client(dbConfig)
-  client.on("error", (err) => {
-    log(`pg client emitted an error: ${err.message}`)
-  })
+  if (dbConfig.ensureDatabaseExists === true) {
+    // Check whether database exists
+    const {user, password, host, port} = dbConfig
+    const client = new pg.Client({
+      database:
+        dbConfig.defaultDatabase != null
+          ? dbConfig.defaultDatabase
+          : "postgres",
+      user,
+      password,
+      host,
+      port,
+    })
+
+    const runWith = withConnection(log, async (connectedClient) => {
+      const result = await connectedClient.query({
+        text: "SELECT 1 FROM pg_database WHERE datname=$1",
+        values: [dbConfig.database],
+      })
+      if (result.rowCount !== 1) {
+        await runCreateQuery(dbConfig.database, log)(connectedClient)
+      }
+    })
+
+    await runWith(client)
+  }
+  {
+    const client = new pg.Client(dbConfig)
+    client.on("error", (err) => {
+      log(`pg client emitted an error: ${err.message}`)
+    })
 
-  const runWith = withConnection(
-    log,
-    withAdvisoryLock(log, runMigrations(intendedMigrations, log)),
-  )
+    const runWith = withConnection(
+      log,
+      withAdvisoryLock(log, runMigrations(intendedMigrations, log)),
+    )
 
-  return runWith(client)
+    return runWith(client)
+  }
 }
 
 function runMigrations(intendedMigrations: Array<Migration>, log: Logger) {

src/types.ts

@@ -21,6 +21,26 @@ export interface ClientParams {
   readonly client: pg.Client | pg.PoolClient | pg.Pool
 }
 
+export type EnsureDatabase =
+  | {
+      /**
+       * Might default to `true` in future versions
+       * @default false
+       */
+      readonly ensureDatabaseExists: true
+      /**
+       * The database to connect to when creating a database (if necessary).
+       * @default postgres
+       */
+      readonly defaultDatabase?: string
+    }
+  | {
+      readonly ensureDatabaseExists?: false
+    }
+
+/**
+ * @deprecated Use `migrate` instead with `ensureDatabaseExists: true`.
+ */
 export type CreateDBConfig =
   | (ConnectionParams & {
       /** The database to connect to when creating the new database. */
@@ -31,7 +51,7 @@ export type CreateDBConfig =
 export type MigrateDBConfig =
   | (ConnectionParams & {
       readonly database: string
-    })
+    } & EnsureDatabase)
   | ClientParams
 
 export type Logger = (msg: string) => void