Pyright/mypy: "expr" has no attribute "id"

Question

Code:

def extract_assignment(assignment: ast.Assign) -> Dict[str, LINES_RANGE]:
    targets = ', '.join(t.id for t in assignment.targets)

pyright/mypy:

error: "expr" has no attribute "id"

From typeshed:

class Assign(stmt):
    targets: typing.List[expr]
    value: expr

Answer 1

Consider the following Code:

x = [100]
x[0] = 200

Running the following ast inspection:

import ast

code = """
x = [100]
x[0] = 200
"""

root = ast.parse(code)
for node in ast.walk(root):
    if isinstance(node, ast.Assign):
        print(type(node.targets[0]))

prints the following:

<class '_ast.Name'>
<class '_ast.Subscript'>

So in this case ast.expr can be either ast.Name or _ast.Subscript. Only ast.Name has an id attribute.

To use only ast.Names use the following code:

targets = ', '.join(t.id for t in assignment.targets if isinstance(t, ast.Name))