hasTable() doesn't resolve with a boolean

Hi, I am using knex schema builder to create the database tables

// create categories table
db.hasTable('categories').then(function (exists) {
  debug(exists)
  if ( exists ) return

  return db.createTable('categories', function (table) {
    table.increments('id')
    table.string('name').notNullable()
    table.string('slug').notNullable().index()
  })
}).then(function () { debug("Table `categories` created") })

// create tags table
db.hasTable('tags').then(function (exists) {
  debug(exists)
  if ( exists ) return

  return db.createTable('tags', function (table) {
    table.increments('id')
    table.string('name').notNullable()
    table.string('slug').notNullable().index()
  })
}).then(function () { debug("Table `tags` created") })

after debugging, exists is an array instead of a boolean, below the output of the console

database [ true, false ] +0ms      <= 
database [ true, false ] +4ms
database Table `categories` created +2ms
database Table `tags` created +0ms

true means that the table categories already exist, tags does not.

[wubzz]

I’m pretty sure this is caused by reusing the schema reference rather than instantianting a new reference each time.

For example this:

const schema = knex.schema;

return schema.hasTable('test') //Runs hasTable test
.then(console.log)// true
.then(() => schema.hasTable('test2')) //Runs hasTable test AND hasTable test2
.then(console.log); //[true, false] -- Since two queries run

The schema reference is still just a query builder. So everytime .then is called, it will run the queries from the builder chain.

Doing this should solve the ‘strangeness’:

return knex.schema.hasTable('test') //Runs hasTable test
.then(console.log)// true
.then(() => knex.schema.hasTable('test2')) //Runs hasTable test2
.then(console.log); //false

Or even better:

const schema = knex.schema;

return schema.hasTable('test')
.then(() => schema.hasTable('test2'))
.spread((hasTableTest, hasTableTest2) => {...})

I wouldn’t consider this a bug. @elhigu What do you think?

CC @tgriesser @jurko-gospodnetic

[piranna]

I stumbled with the same issue during the last 2 hours, I find It good as an optimización but should be shown in the docs. Better, has two methods, hasTable() that always returns a Booleana, and hasTables() that always returns an Array of Booleana