hide.libsonnet

// "hide" a field with a given field name or matching a given predicate.
// Optionally, change the value of the field being mapped.
//
// This is useful until jsonnet gains the ability of using "::" in object comprehension, see
// https://github.com/google/jsonnet/issues/312#issuecomment-1580533298
local hide(obj, field=null, pred=function(name) (name == field), map=function(value) value) =
  std.foldl(
    function(acc, f)
      if pred(f.key) then
        acc { [f.key]:: map(f.value) }
      else
        acc { [f.key]: f.value },
    std.objectKeysValues(obj),
    {}
  );

assert std.assertEqual(
  hide({ a: 1, b: 2 }, field='b'),
  { a: 1 },
);

assert std.assertEqual(
  hide({ a: 1, b: 2 }, field='b').b,
  2,
);

assert std.assertEqual(
  hide({ a: 1, _b: 2 }, pred=function(name) std.startsWith(name, '_')),
  { a: 1 },
);

assert std.assertEqual(
  hide({ a: 1, b: 2 }, field='b', map=function(_) null).b,
  null,
);


hide