Resolving the str Object Attribute Error When Writing Dictionaries to CSV in Python 3

Learn how to fix the common `str object has no attribute keys` error in Python 3 when writing a dictionary to CSV. Discover the proper way to structure your data for successful CSV export!
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Resolving the str Object Attribute Error When Writing Dictionaries to CSV in Python 3

If you're a programmer, you may have faced certain challenges while transitioning from Python 2 to Python 3. One particular issue that can stump even the most seasoned developers is the AttributeError: 'str' object has no attribute 'keys' when attempting to write a dictionary to a CSV file in Python 3. In this post, we'll dive into this error, what causes it, and how you can solve it efficiently.

Understanding the Problem

In Python 2.7, your script may have worked perfectly, converting lists into a dictionary and exporting that dictionary to a CSV file. However, once you try to run this script in Python 3, you may encounter the error mentioned above. This problem often occurs due to a misunderstanding of how csv.DictWriter expects data.

Here's a brief overview of your initial approach that led to the error:

[[See Video to Reveal this Text or Code Snippet]]

The key issue here is that idDict is being treated as a string rather than a list of dictionaries that writerows can work with.

The Solution: Properly Formatting the Data

The solution lies in restructuring your data correctly. csv.DictWriter expects an iterable of dictionaries—for each row, you need to provide a dictionary where the keys match the header names you've defined. Here’s how you can do that:

Step 1: Create a List of Dictionaries

Instead of creating a single dictionary from your lists, format your data into a list of dictionaries using list comprehension. Here's an updated version of your code:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Write to CSV File

Now that you have your idDict correctly formatted as a list of dictionaries, writing to the CSV file becomes straightforward:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the List Comprehension

The line of code used to create the list of dictionaries can be a bit tricky at first glance, so let’s break it down:

enumerate(idList): This function returns both the index and value from idList.

{'id': v, 'pagetitle': pageTitles[i]}: For each item, we create a dictionary where the key is 'id' and the value is the current value (v) from idList, and similarly for 'pagetitle' using corresponding values from pageTitles.

Example Output of idDict

The final structure of idDict will look like this:

[[See Video to Reveal this Text or Code Snippet]]

This format is exactly what DictWriter needs!

Conclusion

Encountering the str object has no attribute keys error when writing a CSV in Python 3 can be frustrating, particularly after successfully running your script in Python 2. By properly structuring your data as a list of dictionaries, you can avoid this common pitfall and successfully export data to CSV files. By following the above steps and understanding the underlying mechanics, you'll ensure a smooth experience with your Python scripts moving forward.

With these adjustments, you can confidently continue using CSV exports in Python 3. Happy coding!