How to Resolve \'Too Many Values to Unpack\' When Iterating Over a Dictionary with Key-Value Lists?

Too Many Values to Unpack: Resolving Iteration Over a Dictionary

When iterating over a dictionary with key-value pairs, where the values are lists, you may encounter the error "too many values to unpack" if your code attempts to unpack both the key and the value simultaneously.

Consider the following example:

<code class="python">first_names = ['foo', 'bar']
last_names = ['gravy', 'snowman']

fields = {
    'first_names': first_names,
    'last_name': last_names,
}        </code>

When attempting to iterate over this dictionary using the following code:

<code class="python">for field, possible_values in fields:  # error happens on this line</code>

You will encounter the "too many values to unpack" error because the iteration attempts to unpack both the key (field) and the value (possible_values) of the dictionary simultaneously. To resolve this, you need to use the appropriate method for iterating over dictionaries.

Python 3

In Python 3, you can use the items() method to iterate over the dictionary's key-value pairs. This method returns a list of tuples, where each tuple contains the key and the value of the dictionary:

<code class="python">for field, possible_values in fields.items():
    print(field, possible_values)</code>

Python 2

In Python 2, you can use the iteritems() method to iterate over the dictionary's key-value pairs. This method returns an iterator of tuples, where each tuple contains the key and the value of the dictionary:

<code class="python">for field, possible_values in fields.iteritems():
    print field, possible_values</code>

Additional Information

For more comprehensive information on iterating through dictionaries, including the differences between iteritems() and items() across Python versions, refer to the following resources:

• [Looping Techniques in Python](https://www.digitalocean.com/community/tutorials/how-to-loop-through-dictionaries-in-python)
• [Dictionary Iteration in Python](https://www.pythonforbeginners.com/basics/python-dictionary-iteration)
• [Python 3 Dict iteritems() - iterating over a dictionary](https://www.tutorialspoint.com/python/python_dictionary_iteritems.htm)

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