Skip to content

Fix ${name:-default} ignoring set-but-empty variables #736

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
mayur-dhavan wants to merge 2 commits into from
+10 −1
Closed

Fix ${name:-default} ignoring set-but-empty variables #736

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
d29e0e9
Apply ${name:-default} when the variable is set but empty
mayur-dhavan Oct 25, 2026
31aecc0
Test ${name:-default} with a set-but-empty variable
mayur-dhavan Oct 25, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 6 additions & 1 deletion src/dotenv/variables.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,12 @@ def __hash__(self) -> int:
def resolve(self, env: Mapping[str, Optional[str]]) -> str:
default = self.default if self.default is not None else ""
result = env.get(self.name, default)
return result if result is not None else ""
if result is None:
return ""
# POSIX ${name:-default} also applies when the variable is set but empty.
if result == "" and self.default is not None:
return self.default
return result


def parse_variables(value: str) -> Iterator[Atom]:
Expand Down
4 changes: 4 additions & 0 deletions tests/test_main.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -894,6 +894,10 @@ def test_dotenv_values_file(dotenv_path):
# Undefined
({}, "a=${b}", True, {"a": ""}),
({}, "a=${b:-d}", True, {"a": "d"}),
# Defined but empty: ${name:-default} applies (POSIX semantics)
({"b": ""}, "a=${b:-d}", True, {"a": "d"}),
({}, "b=\na=${b:-d}", True, {"a": "d", "b": ""}),
({"b": ""}, "a=${b}", True, {"a": ""}),
# With quotes
({"b": "c"}, 'a="${b}"', True, {"a": "c"}),
({"b": "c"}, "a='${b}'", True, {"a": "c"}),
Expand Down
Loading