Node.js datatables editor - Filter select option depending on a certain value

I'm using the node.js datatable editor library. When trying to filter the select options depending on a specific field (user_id) in table 'portfolios_isin' like this:

node.js

let editor = new Editor( db, 'portfolios_isin_mm' )
    .fields(
        new Field( 'portfolios_isin_mm.account_id' ),
        new Field( 'portfolios_isin_mm.user_id' ),
        new Field( 'portfolios_isin_mm.uid_foreign' )
            .options(new Options()
                .table('portfolios_isin')
                .value('id')
                .label('portfolio_name')
                .where(() => {  
                    //this.where('user_id', '=', '1')
                    this.where('portfolios_isin.user_id', '=', '1')
                })
            ),
        new Field( 'securities.issuer_name' )
    )

    .leftJoin( 'portfolios_isin', 'portfolios_isin.id', '=', 'portfolios_isin_mm.uid_foreign' );

I'm getting this Error:

TypeError: this.where is not a function
    at Builder.Editor.fields.Field.options.Options.table.value.label.where (/home/project/controllers/myproject.js:359:30)
    at Formatter.compileCallback (/home/project/node_modules/knex/lib/formatter.js:161:14)
    at Formatter.rawOrFn (/home/project/node_modules/knex/lib/formatter.js:104:36)
    at QueryCompiler_MySQL.whereWrapped (/home/project/node_modules/knex/lib/query/compiler.js:531:30)
    at QueryCompiler_MySQL.where (/home/project/node_modules/knex/lib/query/compiler.js:314:32)
    at /home/project/node_modules/knex/lib/query/compiler.js:147:30
    at Array.map (<anonymous>)
    at QueryCompiler_MySQL.select (/home/project/node_modules/knex/lib/query/compiler.js:146:33)
    at QueryCompiler_MySQL.toSQL (/home/project/node_modules/knex/lib/query/compiler.js:108:27)
    at Builder.toSQL (/home/project/node_modules/knex/lib/query/builder.js:115:44)
    at /home/project/node_modules/knex/lib/runner.js:56:32
    at tryCatcher (/home/project/node_modules/bluebird/js/release/util.js:16:23)
    at /home/project/node_modules/bluebird/js/release/using.js:185:26
    at tryCatcher (/home/project/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/home/project/node_modules/bluebird/js/release/promise.js:512:31)
    at Promise._settlePromise (/home/project/node_modules/bluebird/js/release/promise.js:569:18)

According to the docs https://editor.datatables.net/manual/nodejs/joins this is the way to do it. I have a similar project where I use the php datatable editor libraries (and all is working just fine) ... there I can filter the options like this:

php:

Editor::inst( $db, 'portfolios_isin_mm' )
    ->fields(
        Field::inst( 'portfolios_isin_mm.account_id' ),
        Field::inst( 'portfolios_isin_mm.user_id' ),
        Field::inst( 'portfolios_isin_mm.uid_foreign' )
            ->options( 'portfolios_isin', 'id', 'portfolio_name', function ($q) {
                $q->where( 'portfolios_isin.user_id', '1', '=' );
            }),
        Field::inst( 'securities.issuer_name' )         
    )

    ->leftJoin( 'portfolios_isin', 'portfolios_isin.id', '=', 'portfolios_isin_mm.uid_foreign' )    

How do I get to filter the option values in editor for node.js?

this.where is out of the scope where the function where exist, because you are using an arrow function which binds this to the outer/parent scope.

Try this instead:

.options(new Options()
                .table('portfolios_isin')
                .value('id')
                .label('portfolio_name')
                .where(function(){  
                    this.where('portfolios_isin.user_id', '=', '1')
                })
            ),