How To Resolve The TypeError: unhashable type: ‘dict’ in Python

To fix TypeError: unhashable type: ‘dict’ error in Python, there are 2 solutions we have effectively tested: Using the correct dictionary key and Using the item() method. Follow the article to better understand.

Why does the error “Unhashable type: ‘dict’ ” in Python happen?

Before talking about the error, we have a few definitions for you: TypeError , Unhashable , dict.

What is TypeError? 

The ‘ TypeError ‘ occurs when the data types are incompatible with the same function.

What is Unhashable?

‘Unhashable’ is a feature in Python used to determine if an object has a hash value.

An object is hashable if it has a hash value for the duration of its existence.

A hash value is a key for a dictionary or an element of a set.

What is dict? 

‘Dict’ stands for dictionary in Python.

Dictionary in Python has the function to store values ​​of data in ‘key: value’ pairs. 

Dictionary is a collection that is ordered*, non-duplicate, and interchangeable.

NOTE: since version 3.7 the dictionaries are sorted

Example:

infor = {
    "name": "John",
    "age": "15",
}

print(infor)

Output: 

{'name': 'John', 'age': '15'}

Dictionary consists of two components: key and value.

Key is an identifier to associate with a value. As stated above, only hash objects can be keys in a dictionary. Therefore, one dictionary cannot be used as a key in another dictionary.

To add a key to the dictionary, you must specify a valid key. For example, ” infor” is a valid key but { ” infor”: ” name”} is not.

An illustrative example of a false situation:

cars = [
    {"brand": "Kia", "sold": 4 },
    {"brand": "Toyota", "sold": 7},       
    {"brand": "Ford", "sold": 8}
]
soldMoreThanFour = {}

The list “cars” contains three dictionaries. Each dictionary contains ‘key’ and ‘value’. It is named “brand” and “sold”.

I then run a for loop through the list of “cars” and filter out the cars sold more than five times. When the search is complete, it will be added to the dictionary “sold_more_than_four “:

cars = [
    {"brand": "FORD", "sold": 4},
    {"brand": "TOYOTA", "sold": 8},
    {"brand": "KIA", "sold": 9}
]

soldMoreThanFour = {}

for a in cars:
	if a["sold"] > 4:
		soldMoreThanFour[a] = a["sold"]
		print(a["name"] + " has been sold more than four times.")

print(soldMoreThanFour)

Output:

TypeError: unhashable type: 'dict'

The program doesn’t work because the value ‘a’ is a dictionary in the “cars” list

How to fix this error?

Method 1: Using correct dictionary key

Change the wrong command: soldMoreThanFour[a] = a["sold"] to correct command: soldMoreThanFour[a["brand"]] = a["sold"]

Example:

cars = [
    {"brand": "FORD", "sold": 4},
    {"brand": "TOYOTA", "sold": 8},
    {"brand": "KIA", "sold": 9}
]
    
soldMoreThanFour = {}

for a in cars:
	if a["sold"] > 4:
		soldMoreThanFour[a["brand"]] = a["sold"]
		print(a["brand"] + " has been sold more than four times.")

print(soldMoreThanFour)

Output:

TOYOTA has been sold more than four times.
KIA has been sold more than four times.
{'TOYOTA': 8, 'KIA': 9}

Method 2: Using the item() method

The item() method returns an object containing a dictionary’s key and value pairs, which are called view objects.

Syntax:

dictionary.items()

Example:

infor = {
   "weight": "45",
   "age": "14"
}

person = infor.items()
infor["age"] = 17

print(person)

Output:

dict_items([('weight', '45'), ('age', 17)])

Summary

Read this article to find out the answer for error “TypeError: unhashable type: ‘dict’” in Python. If you have any questions about this issue, please leave a comment below. I will answer your questions.