How to Solve Python AttributeError: ‘str’ object has no attribute ‘append’

In Python, Strings are arrays of bytes representing Unicode characters. Although Strings are container type objects, like lists, you cannot append to a string. If you try to call the append() method on a string to add more characters, you will raise the error AttributeError: ‘str’ object has no attribute ‘append’.

To solve this error, you can use the concatenation operator + to add a string to another string.

This tutorial will go through how to solve this error, with the help of code examples.

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AttributeError: ‘str’ object has no attribute ‘append’

AttributeError occurs in a Python program when we try to access an attribute (method or property) that does not exist for a particular object. 

The attribute that does not exist in this case is “append”. We can use append on list objects, For example:

x = [1, 2, 3]
x.append(4)
print(x)

[1, 2, 3, 4]

However, if we try to append to a string, we will raise the Attribute error, for example:

string = "The dog"
new_string = string.append(" catches the ball")

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
      1 string = "The dog"
      2 
----≻ 3 new_string = string.append(" catches the ball")
AttributeError: 'str' object has no attribute 'append'

Example

Let’s look at an example where we have a list of strings. Each string is a name of a vegetable. We want to get the vegetable names that begin with c and print them to the console. The code is as follows:

vegetables = ["broccolli", "carrot", "courgette", "spinach", "beetroot", "cabbage", "asparagus", "cauliflower"]
veg_starting_with_c = ""
for veg in vegetables:
    if veg.startswith("c"):
        veg_starting_with_c.append(veg)
print(f'Vegetables starting with c: {veg_starting_with_c}')

We define a for loop to iterate over the strings in the list. We use the startswith() method to check if the string starts with c and then try to append the string to an empty string. Once the loop ends we try to print the completed string to the console.

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
      7     if veg.startswith("c"):
      8 
----≻ 9         veg_starting_with_c.append(veg)
     10 
     11 print(f'Vegetables starting with c: {veg_starting_with_c}')
AttributeError: 'str' object has no attribute 'append'

The error occurs because the variable veg_starting_with_c is a string, we cannot call the append() method on a string.

Solution #1

To solve this error, we can use the concatenation operator to add the strings to the empty string. Note that strings are immutable, so we need to create a new string variable each time we use the concatenation operator. Let’s look at the revised code:

vegetables = ["broccolli", "carrot", "courgette", "spinach", "beetroot",
cabbage", "asparagus", "cauliflower"]
veg_starting_with_c = ""
for veg in vegetables:
    if veg.startswith("c"):
        
        veg_starting_with_c = veg_starting_with_c + " " + veg
        
print(f'Vegetables starting with c: {veg_starting_with_c}')

Let’s run the code to get the result:

Vegetables starting with c:  carrot courgette cabbage cauliflower

Solution #2

Instead of concatenating strings, we can use a list and call the append method. Let’s look at the revised code:

vegetables = ["broccolli", "carrot", "courgette", "spinach", "beetroot","cabbage", "asparagus", "cauliflower"]
veg_starting_with_c = []
for veg in vegetables:
    if veg.startswith("c"):
        
        veg_starting_with_c.append(veg)
        
print(f"Vegetables starting with c: {' '.join(veg_starting_with_c)}")

We can use the join() method to convert the list to a string. Let’s run the code to get the result:

Vegetables starting with c: carrot courgette cabbage cauliflower

Summary

Congratulations on reading to the end of this tutorial!

For further reading on AttributeErrors with string objects, go to the article:

How to Solve Python AttributeError: ‘str’ object has no attribute ‘trim’

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