I am having a strange problem. I have a method that returns a boolean. In turn I need the result of that function returned again since I cant directly call the method from the front-end. Here’s my code:
# this uses bottle py framework and should return a value to the html front-end
@get('/create/additive/<name>')
def createAdditive(name):
return pump.createAdditive(name)
def createAdditive(self, name):
additiveInsertQuery = """ INSERT INTO additives
SET name = '""" + name + """'"""
try:
self.cursor.execute(additiveInsertQuery)
self.db.commit()
return True
except:
self.db.rollback()
return False
This throws an exception: TypeError(«‘bool’ object is not iterable»,)
I don’t get this error at all since I am not attempting to «iterate» the bool value, only to return it.
If I return a string instead of boolean or int it works as expected. What could be an issue here?
Traceback:
Traceback (most recent call last):
File "C:Python33libsite-packagesbottle.py", line 821, in _cast
out = iter(out)
TypeError: 'bool' object is not iterable
Python TypeError: 'bool' object is not iterable message means a Boolean object (True or False) is being used in a context where an iterable object (like a list or tuple) is expected.
To solve this error, you need to correct the line where you iterate over a bool object.
An iterable object is an object that can be looped over, such as a list, tuple, or string.
In contrast, a Boolean object is a single value and cannot be looped over. Consider the code below:
x = True
for value in x: # ❗️
print(value)
The for loop in the code above tries to loop over the x variable, which is a Boolean.
This causes the following error:
Traceback (most recent call last):
File ...
for value in x:
TypeError: 'bool' object is not iterable
To avoid the error above, you need to pass an iterable object such as a list, a string, or a tuple to the for statement:
x = ["apple", "orange"]
for value in x:
print(value)
# apple
# orange
One common cause of this error is when you reassign your variable value after it has been created.
In the following example, the x variable is first initialized as a list, but got reassigned as Boolean down the line:
# x initialized as a list
x = [1, 2, 3]
# x reassigned as a boolean
x = True
When you use the x variable after the x = True line, then you will get the 'bool' object is not iterable error.
Another common scenario where this error occurs is when you pass a Boolean object to a function that requires an iterable.
For example, the list(), tuple(), set(), and dict() functions all require an iterable to be passed:
x = True
# ❌ TypeError: 'bool' object is not iterable
list(x)
tuple(x)
set(x)
dict(x)
You can also add an if statement to check if your variable is a boolean:
x = True
if type(x) == bool:
print("x is of type Boolean.") # ✅
else:
print("x is not of type Boolean.")
Or you can also use the isinstance() function to check if x is an instance of the bool class:
x = True
if isinstance(x, bool):
print("x is of type Boolean.") # ✅
else:
print("x is not of type Boolean.")
When you see a variable identified as a Boolean, you need to inspect your code and make sure that the variable is not re-assigned as Boolean after it has been declared.
You will avoid this error as long as you don’t pass a Boolean object where an iterable is expected.
The “typeerror: ‘bool’ object is not iterable” is an error message in Python.
If you are wondering how to resolve this type error, keep reading.
In this article, you’ll get the solution that will fix the “bool object is not iterable” type error.
Aside from that, we’ll give you some insight into this error and why it occurs in Python scripts.
A ‘bool’ object is a data type in Python that represents a boolean value.
“Boolean” value represents one of two values: True or False.
These values are used to represent the truth value of an expression.
For instance, if you want to compare two values using a comparison operator such as (<, >, !=, ==, <=, or >=), the expression is evaluated.
And Python returns a “boolean” value (True or False) indicating whether the comparison is true.
Moreover, “bool” objects are often used in conditional statements and loops to control the flow of a program.
However, it’s important to note that “boolean” values and operators are not sequences that can be iterated over.
What is “typeerror: ‘bool’ object is not iterable”?
The “typeerror: ‘bool’ object is not iterable” occurs when you try to iterate over a boolean value (true or false) instead of an iterable object (like a list, string or tuple).
For example:
my_bool = True
for sample in my_bool:
print(sample)
If you run this code, it will throw an error message since a boolean value is not iterable.
TypeError: 'bool' object is not iterableThis is not allowed because “boolean value” is not a collection or sequence that can be iterated over.
How to fix “typeerror: ‘bool’ object is not iterable”?
Here are the following solutions that will help you to fix this type error:
1: Assign an iterable object to the variable
Rather than assigning a boolean value to the variable. You can assign an iterable object such as a list, string, or tuple.
my_list = [10, 20, 30, 40, 50]
for sample in my_list:
print(sample)As you can see in this example code, we assign a list to the variable my_list and iterate over it using a for loop.
Since a list is iterable, this code will run smoothly.
Output:
10
20
30
40
502: Use if statement
When you need to check on a boolean value, you can simply use an if statement instead of a for loop.
my_bool = True
if my_bool:
print("This example is True")
else:
print("The example is False")In this example code, we check if the boolean value “my_bool” is True using an if statement.
If the value is True, then it will print a message indicating that “This example is True”.
Otherwise, it will print a different message.
Output:
This example is True3: Convert the boolean value to an iterable object
When you need to iterate over a boolean value, you just have to convert it to an iterable object, such as a list, string, or tuple.
my_bool = True
my_list = [my_bool]
for sample in my_list:
print(sample)Output:
True4: Use generator expression
When you need to iterate over multiple boolean values, you can use a generator expression to create an iterable object.
my_bools = [True, False, True]
result = (x for x in my_bools if x)
for sample in result:
print(sample)As you can see in this example code, we use a generator expression to create an iterable object.
That contains only the True values from the list my_bools.
Then iterate over this iterable object using a for loop.
Output;
True
True5: Use the isinstance() function
Before iterating over a variable, you can check its type using the isinstance() function to ensure it is an iterable object.
my_var = True
if isinstance(my_var, (list, tuple, str)):
for sample in my_var:
print(sample)
else:
print("my_var is not iterable")Here, we use the isinstance() function to check if the variable my_var is an instance of a list, tuple, or string.
Since it is not, it will print a message rather than try to iterate over it.
Output:
my_var is not iterableConclusion
In conclusion, the “typeerror: ‘bool’ object is not iterable” occurs when you try to iterate over a boolean value (True or False) instead of an iterable object (like a list, string or tuple).
Luckily, this article provided several solutions above so that you can fix the “bool object is not iterable” error message.
We are hoping that this article provided you with sufficient solutions to get rid of the error.
You could also check out other “typeerror” articles that may help you in the future if you encounter them.
- Typeerror unsupported operand type s for str and float
- Typeerror: ‘dict_keys’ object is not subscriptable
- Typeerror: object of type ndarray is not json serializable
Thank you very much for reading to the end of this article.
When working with Python code, you may encounter the error message ‘TypeError: ‘bool’ object is not iterable’. This error usually occurs when you try to iterate over a boolean value (True or False) using a loop or a comprehension. In this guide, we will explore the causes of this error and provide step-by-step solutions on how to resolve it.
Causes of ‘TypeError: ‘bool’ Object is Not Iterable’ Error in Python Code
The ‘TypeError: ‘bool’ object is not iterable’ error occurs when you try to iterate over a boolean value using a loop or a comprehension. For example, consider the following code snippet:
flag = True
for i in flag:
print(i)
This code will result in the following error message:
TypeError: 'bool' object is not iterable
The error occurs because the bool type is not iterable in Python. You cannot loop over a boolean value.
Resolving ‘TypeError: ‘bool’ Object is Not Iterable’ Error in Python Code
To resolve the ‘TypeError: ‘bool’ object is not iterable’ error, you need to ensure that you are not trying to iterate over a boolean value. There are several ways to do this:
1. Check the Type of the Variable
Before iterating over a variable, check its type to ensure that it is iterable. You can use the type() function to check the type of a variable. For example:
flag = True
if type(flag) == bool:
print("Variable is a boolean value")
else:
print("Variable is not a boolean value")
This code will output:
Variable is a boolean value
2. Convert the Boolean Value to an Iterable
If you need to iterate over a boolean value, you can convert it to an iterable using the range() function. For example:
flag = True
for i in range(int(flag)):
print(i)
This code will output:
0
1
3. Use a List Comprehension
If you need to iterate over a boolean value and create a list, you can use a list comprehension. For example:
flag = True
lst = [i for i in range(int(flag))]
print(lst)
This code will output:
[0, 1]
FAQ
What is the ‘bool’ type in Python?
The ‘bool’ type in Python represents the two boolean values True and False.
Why is the ‘bool’ type not iterable in Python?
The ‘bool’ type is not iterable in Python because it only has two possible values (True and False).
How can I check the type of a variable in Python?
You can check the type of a variable in Python using the type() function.
Can I convert a boolean value to an iterable in Python?
Yes, you can convert a boolean value to an iterable in Python using the range() function.
What is a list comprehension in Python?
A list comprehension is a concise way to create a list in Python. It consists of an expression followed by a for clause and an optional if clause.
TypeError: ‘bool’ object is not iterable in Python [Solved] | bobbyhadz
The Python TypeError: ‘bool’ object is not iterable occurs when we try to iterate over a boolean value (`True` or `False`) instead of an iterable (e.g. a list). To solve the error, track down where the variable got assigned a boolean and correct the assignment.
Blog — Bobby Hadz
The python error TypeError: argument of type ‘bool’ is not iterable happens when the membership operators evaluates a value with a boolean variable. The python membership operator (in, not in) tests a value in an iterable objects such as set, tuple, dict, list etc. If the iterable object in the membership operator is passed as a boolean variable then the error is thrown.
The membership operator shall detect a boolean value as an iterable object. The boolean value is a single object. The member operator returns true if the value is found in an iterable object.
The Member Operator (in, not in) is used to check whether or not the given value is present in an iterable object. If the value exists in the iterable object then it returns true. If the iterable object is a boolean variable then the value is hard to verify. The error TypeError: argument of type ‘bool’ is not iterable is due to checking the value in Boolean variable.
If the right iterable object is passed in the membership operator, such as tuple, set, dictionary, list etc., then the error will not occur.
Exception
When the error TypeError: argument of type ‘bool’ is not iterable happens, this error displays the stack trace as shown below.
Traceback (most recent call last):
File "/Users/python/Desktop/test.py", line 3, in <module>
print x in y
TypeError: argument of type 'bool' is not iterable
[Finished in 0.1s with exit code 1]How to reproduce this error
To verify a value the membership operator needs an iterable object. If the iterable object is passed as a boolean variable then it is difficult to check the value. Therefore, the error TypeError: argument of type ‘bool’ is not iterable will be thrown.
In the example below, two variables are assigned to x and y with a boolean value. The x value is verified with the y value used by the membership operator (in, not in). Since the y value is a boolean type, it will throw an error.
x = True
y = True
print x in yOutput
Traceback (most recent call last):
File "/Users/python/Desktop/test.py", line 3, in <module>
print x in y
TypeError: argument of type 'bool' is not iterable
[Finished in 0.1s with exit code 1]Solution 1
The membership operator (in, not in) requires an iterable object to search for a present or not present value. To check the value, the iterable object such as list, tuple, or dictionary should be used. If a valid iterable object is passed in the membership operator, then the error will be resolved.
x = True
y = [ True ]
print x in yOutput
True
[Finished in 0.1s]Solution 2
If you wish to compare a boolean value with another boolean value, you should not use the Membership Operator. The logical operator is often used to equate two boolean values. In python the logical operator can compare two values. The code below shows how the value can be used for comparison.
x = True
y = True
print x == yOutput
True
[Finished in 0.1s]Solution 3
If the iterable object in the Membership Operator is an invalid boolean value, then you can change it to execute in alternate flow. This will fix the error. The iterable object must be validated before proceed with the membership operator.
x = True
y = True
if isinstance(y, bool) :
print "Value is boolean"
else:
print x == yOutput
Value is boolean
[Finished in 0.1s]Solution 4
If the iterable object is unknown, the expected iterable object should be checked before the membership operator is invoked. If the object is an iterable object, the membership operator is called with the python value. Otherwise, take an alternate flow.
x = True
y = True
if type(y) in (list,tuple,dict, str):
print x in y
else:
print "not a list"Output
not a list
[Finished in 0.1s]Solution 5
The try and except block is used to capture the unusual run time errors. If the python variable contains iterable object, then it will execute in the try block. If the python variable contains the uniterable value, then the except block will handle the error.
x = True
y = True
try :
print x in y
except :
print "not a list"Output
not a list
[Finished in 0.1s]