Load a combobox using a mysql query

temerariomalaga

I have a datatable for articles. It have the name of the article and the code of the provider. The code of the provider is a foreign key and I need to load it from the provider table but the generator add a static combobox with predefined values and I don't know how to load the combobox using a query. The code of the combobox is the following.
[code]{
"label": "C\u00f3digo Proveedor",
"name": "id",
"type": "select",
"ipOpts": [
{
"label": "Recambios Serrano",
"value": "1"
},
{
"label": " Liderpaper ",
"value": " 2 "
}
]
},
[/code]