API get all proposal, order, invoice based on specific fk_project value

I would like to through the API get a list of all proposals (and later orders and invoices) where the fk_project has a specific value (in my current usecase that value is 6 and I knwo it before hand)

I tried setting the sqlfilter to (t.fk_project:=:6)

But that column apparently does not exist :frowning: even though I can see that when I extract the json for a order or proposal or invoice that has a project value set.

  "error": {
    "code": 503,
    "message": "Service Unavailable: Error when retrieve commande list : Unknown column 't.fk_project' in 'where clause'"
  "debug": {
    "source": "api_orders.class.php:251 at call stage",
    "stages": {
      "success": [
      "failure": [

Okay, to answer my own question, as I just found a solution


I have to name it fk_projet not fk_project even though the json says "fk_project": "6",

(I find it slightly annoying that field names in database and json does not match)