Keeping strings in ast.literal_eval to dict

Question

If I use literal_eval on some strings to get a dictionary, it works fine:

import ast string = '{123: True, 456: False}' In: ast.literal_eval(string) Out: {123: True, 456: False}

But if the string has a string within it, I get an error:

string = '{123: Foo, 456: Bar}' In: ast.literal_eval(string) Out: ValueError: malformed node or string: <_ast.Name object at 0x7f7d5faae9e8>

How can I keep strings in the second literal_eval?

Those aren't strings. In the code {123: Foo, 456: Bar}, Foo and Bar are python objects. Did you mean {123: "Foo", 456: "Bar"}? — RishiG
– RishiG, Commented Nov 22, 2019 at 21:53
@RishiG: They're not Python objects, they're interpreted as the names or identifiers of objects. — martineau
– martineau, Commented Nov 22, 2019 at 22:17
Similar question asked here: stackoverflow.com/questions/22235419/… — oneturkmen
– oneturkmen, Commented Nov 22, 2019 at 23:43

oneturkmen · Accepted Answer · 2019-11-22 23:08:40Z

2

The example you gave, i.e.

{123: Foo, 456: Bar}

does not contain strings. It contains identifiers Foo and Bar.

A correct string would rather look like:

{123: "Foo", 456: "Bar"}

That's why AST module try to parse, does not see expected literal (number of string), and panics because it sees some identifier. Does that help?

P.S. Thanks @RishiG for pointing out redundant backslashes.

edited Nov 22, 2019 at 23:08

answered Nov 22, 2019 at 21:54

oneturkmen

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6 Comments

RishiG Over a year ago

You don't need the backslashes.

kaya3 Over a year ago

Technically, Foo and Bar are not literals, they are names - in the AST they're represented by Name objects. A literal is an expression which has a fixed value independent of any other code. en.wikipedia.org/wiki/Literal_(computer_programming)

oneturkmen Over a year ago

I believe @snapcrack had strings inside (i.e., "if the string has a string inside"). Otherwise, you are right, Foo and Bar would be identifiers for some Python objects.

martineau Over a year ago

Foo and Bar are interpreted as Python names (aka identifiers), not literal values.

snapcrack Over a year ago

Thanks. This was honestly not a terribly well worded question on my part, but this definitely answers it as written.

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