Fix - NameError: name 'StringIO' is not defined in Python

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Borislav Hadzhiev

Wed Apr 20 20222 min read

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Fix - NameError: name 'StringIO' is not defined in Python #

The Python "NameError: name 'StringIO' is not defined" occurs when we use the StringIO class without importing it first. To solve the error, import the StringIO class from the io module before using it - from io import StringIO.

nameerror name stringio is not defined

Here is an example of how the error occurs.

main.py
# ⛔️ NameError: name 'StringIO' is not defined f = StringIO("some initial text data") print(f)

To solve the error, we have to import the StringIO class from the io module.

main.py
# ✅ import StringIO class first from io import StringIO f = StringIO("some initial text data") print(f)

Alternatively, you can import the entire io module and access the StringIO class as io.StringIO.

main.py
import io f = io.StringIO("some initial text data") print(f)

When you import the entire module, you access its members as io.SomeClass or io.some_function.

Even though the io module is in the Python standard library, we still have to import it before using it.

Also, make sure you haven't imported the module in a nested scope, e.g. a function. Import the module at the top level to be able to use it throughout your code.

In general, importing only the functions and classes that you use in your code is the better approach as it makes your code easier to read.

For example, when we use an import such as import io, it is much harder to see which classes or functions from the io module are being used in the file.

Conversely, when we import specific classes, it is much easier to see which classes and methods from the io module are being used.

The io module provides classes and functions for dealing with various types of I/O, such as text I/O, binary I/O and raw I/O.

You can view all of the classes and functions the io module provides by visiting the official docs.

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