How to avoid KeyError without using try/except?

Question

In the following code snippet:

for record in records:    
  max = record.get_values()['max']

In this code, I am getting max value from record. "records" is a generator object here. The problem is, in some cases max field won't be present. So I am getting KeyError in those cases. I want to assign max = 0 if max isn't present in record. So far I have come with this solution:

try:    
  max = record.get_values()['max']
except:
  max = 0

But I want to avoid using try-except in this case as there are many more lines like this and it will make my code look messy. How can I achieve the same functionality without using try-except or long lines of code? It will be preferable if this can be done in a single line of code.

If record.get_values() returns a dictionary then you could use max = record.get_values().get("max", 0) — user459872
– user459872, Commented Nov 4, 2020 at 12:36

Tasnuva Leeya · Accepted Answer · 2020-11-04 12:44:49Z

4

you can use get() to avoid key error. it will return None for missing key: if record.get_values() returns a dict use:

for record in records:    
  max = record.get_values().get('max')


# will return **None** for missing key by default, you can add a default value if needed.

a simple example is:

emp_dict = {'Name': 'Pankaj', 'ID': 1}

emp_id = emp_dict.get('ID')
emp_role = emp_dict.get('Role')
emp_salary = emp_dict.get('Salary', 0)

print(f'Employee[ID:{emp_id}, Role:{emp_role}, Salary:{emp_salary}]')

# Output: Employee[ID:1, Role:None, Salary:0]

edited Nov 4, 2020 at 12:44

answered Nov 4, 2020 at 12:38

Tasnuva Leeya

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3 Comments

SiHa Over a year ago

Better is to supply a default in the get() call, as already commented.

Jared Smith Over a year ago

.get takes a second argument to return if the key isn't present.

Tasnuva Leeya Over a year ago

default value is optional. you can mention a default value as your wish but by default it will return None. check here if needed w3schools.com/python/ref_dictionary_get.asp

Daniel · Accepted Answer · 2020-11-04 12:38:00Z

-1

You can check if the key "max" exists in the dictionary using a ternary operator.

max = record.get_values()["max"] if "max" in record.get_values().keys() else 0

answered Nov 4, 2020 at 12:38

Daniel

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