knex-query-then-example.js

// Illustrates how calling knex.query() can return a query builder while
// await knex.query() (or knex.query().then(...)) execute the query.

// Basically, the answer is `then()`
// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then
// Stack Overflow post asking the same thing:
// - https://stackoverflow.com/questions/65319822/how-does-knex-await-execute-a-database-query

class QueryBuilder {
  createTable(tableName) {
    // just return the query builder for example purposes
    return this;
  }

  then(resolve) {
    // simulates table creation
    setTimeout(() => {
      resolve("Table created successfully");
    }, 1000);
  }
}

class Knex {
  constructor() {
    this.schema = new QueryBuilder();
  }
}

// Usage Example
const knex = new Knex();

async function main() {
  const nonAwaited = knex.schema.createTable("users");
  console.log("non awaited result:", nonAwaited);

  const awaited = await knex.schema.createTable("users");
  console.log("Awaited result:", awaited);
}

main()