In Python 3, File object does not support the next() method. Instead, Python 3 has a built-in function next, which retrieves the next item from the iterator by invoking its __next__() method. If you try to call next() on a reader object in Python 3, you will raise the AttributeError: ‘_csv.reader’ object has no attribute ‘next.
To solve this error, use next(reader) instead.
This tutorial will go through the error in detail and how to solve it with code examples.
AttributeError: ‘_csv.reader’ object has no attribute ‘next’
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 part of the error ‘_csv.reader’ object has no attribute ‘next‘ tells us that the reader object we are handling does not have the next method as an attribute. Python 3 no longer supports the next method.
Example
Let’s look at an example of opening a file using the csv module and reading the lines. First, we will look at the dataset:
pizza,price margherita,£7.99 pepperoni,£8.99 four cheeses,£10.99 funghi,£8.99
Next, we will load the data into our program using the built-in open method, then create an iterator containing the lines in the file using csv.reader().
import csv
data = open('pizzas.csv', 'r')
reader = csv.reader(data)
The next step involves retrieving the items in the reader iterator using next(). We will call the next() method for times using a for loop.
for i in range(4): line = reader.next() print(line)
Let’s run the code to see the result:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
Input In [3], in <cell line: 1>()
1 for i in range(5):
----> 2 line = reader.next()
3 print(line)
AttributeError: '_csv.reader' object has no attribute 'next'
We get the AttributeError because next() is no longer supported in Python 3.
Solution
We need to use the built-in next() method instead of calling next() on the reader object to solve this error. Let’s look at the revised code:
import csv
data = open('pizzas.csv', 'r')
reader = csv.reader(data)
header = next(reader)
for i in range(4):
line = next(reader)
print(line)
We get the header by calling next(reader) once. Then, we will only print the lines with values in the for loop. Let’s run the code to see the result.
['margherita', '£7.99'] ['pepperoni', '£8.99'] ['four cheeses', '£10.99'] ['funghi', '£8.99']
We successfully printed the lines to the console. Note that using the next() invokes the __next__() method of the iterator. Therefore we can also call the __next__ method on the iterator, though this is not common. Let’s look at the code:
import csv
data = open('pizzas.csv', 'r')
reader = csv.reader(data)
header = reader.__next__()
for i in range(4):
line = reader.__next__()
print(line)
['margherita', '£7.99'] ['pepperoni', '£8.99'] ['four cheeses', '£10.99'] ['funghi', '£8.99']
Summary
Congratulations on reading to the end of this tutorial! The AttributeError ‘_csv.reader’ object has no attribute ‘next’ occurs when you try to call the next() method on a csv.reader object in Python 3. To solve this error, you need to call the built-in next() method and pass the reader object to it as a parameter.
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