hasAttrByPath
lib.hasAttrByPath
Docs pulled from | This Revision | about 9 hours ago
Return if an attribute from nested attribute set exists.
Nix has a has attribute operator ?, which is sufficient for such queries, as long as the number of attributes is static. For example:
(x?a.b) == hasAttrByPath ["a" "b"] x
# and
(x?${f p}."example.com") == hasAttrByPath [ (f p) "example.com" ] x
Laws:
-
hasAttrByPath [] x == true
Inputs
attrPath-
A list of strings representing the attribute path to check from
set e-
The nested attribute set to check
Type
hasAttrByPath :: [String] -> AttrSet -> Bool
Examples
lib.attrsets.hasAttrByPath usage example
x = { a = { b = 3; }; }
hasAttrByPath ["a" "b"] x
=> true
hasAttrByPath ["z" "z"] x
=> false
hasAttrByPath [] (throw "no need")
=> true