Flow cannot find schema property on knex

Question

I'm working on a project which uses knex for database connections. I'm also using flow for typings. I'm attempting to connect to the database as follows:

const db = knex({
    client: 'mysql',
    connection: {
        host: containerized() ? 'database' : process.env.DB_URL || 'localhost',
        user: process.env.DB_USER || 'user',
        password: process.env.DB_PASSWORD || 'password',
        database: process.env.DB_DATABASE || 'database',
    },
});

where db has the type Knex$Knex. I attempt to set up the database with:

export function init(): Promise<Knex$Knex<*>> {
    return new Promise((resolve, reject) => {
        PromiseReduce([
            () => db.schema.hasTable('users').then((exists) => {
                if (!exists) {
                    return db.schema.createTable('users', (table) => {
                        ...
                    });
                }
                return null;
            }),
            ...
        ]).then(resolve).catch(reject);
    }).then(() => db);
}

This all works when it's run, but flow is erroring, saying that db.schema is not a property of Knex$Knex; and looking at the type declaration, this is the case. Is there a preferred method to do this, or is it simply a case of the flow declarations being wrong?

Answer 1

This is because the flow-typed definition for knex v0.14.x does not include typing for the schema.

The error can be quickly fixed locally by adding schema: Object to the declaration of the Knex$Knex<R> class.

A fix for the issue would require typing the schema for knex properly and adding it to the flow-typed repository.