getattr()

Dot access when the attribute name is a string — with an optional default that replaces try/except AttributeError.

Built-in functionPython 1.0+
Common call
value = getattr(obj, name, None)
Returns
the attribute, or default, or AttributeError
Replaces
try: obj.name except AttributeError: default
Watch out
without a default, AttributeError propagates — catch it or provide one
getattr(objectobject — Any object. getattr walks its class hierarchy to find the attribute.type: Any · required, name[, default])
→ Any

Parameters

NameTypeRequiredDescription
objectAnyyesAny object. getattr walks its class hierarchy to find the attribute.
namestryesThe attribute name as a STRING. Not the identifier — a runtime value.
defaultAnynoThe fallback value returned when the attribute is missing. Any type; None is common but a sentinel object is safer if None could be a real value.

Return value

Any — The attribute value. If missing: returns default when supplied, raises AttributeError otherwise. The equivalent of `object.name` when `name` is a runtime string.

Common patterns

Optional attribute with a default
Replace try/except AttributeError with a one-line getattr.
timeout = getattr(config, "timeout", 30)
Dispatch by attribute name
Common in CLI parsers and plugin registries.
handler = getattr(handlers, command, default_handler)
handler(*args)
Method call by runtime string
When the method name comes from data — config, user input, etc.
method = getattr(obj, name)
result = method(*args, **kwargs)
Sentinel for the "None is a real value" case
When None could be legitimate, an object() sentinel disambiguates.
_missing = object()
val = getattr(obj, name, _missing)
if val is _missing:
    ...   # truly absent

Examples

1. Method by name
getattr(str, "upper")
Returns
<method 'upper' of 'str' objects>
2. Instance method
getattr("hi", "upper")()
Returns
"HI"
3. With default
getattr(obj, "missing", "fallback")
Returns
"fallback"
4. Without default
getattr({}, "missing")
Returns
AttributeError
5. None as default
getattr(obj, "missing", None)
Returns
None
6. Call after getattr
getattr(items, "sort")()
Returns
None # list.sort mutates

Pitfalls

1. AttributeError without a default
The single most common getattr surprise. Without a third argument, a missing attribute raises AttributeError. In modern code, always provide a default unless you truly want the exception.
Uncaught raise
getattr(obj, "missing")
AttributeError: ...
Default it
getattr(obj, "missing", None)
None
2. A property that raises AttributeError looks &quot;missing&quot;
If a @property internally raises AttributeError, getattr returns the DEFAULT — the bug looks like the attribute is absent. Use try/except and log the error for properties with side effects.
Bug hidden
@property
def x(self):
    return self.does_not_exist

getattr(obj, "x", None)
None # bug looks like &quot;missing&quot;
Try/except with logging
try:
    val = obj.x
except AttributeError as e:
    log.warning("no x: %s", e)
error visible
3. Class attributes AND instance attributes
getattr walks the MRO. A method defined on the class is returned via an instance getattr. For instance-only attributes, check obj.__dict__ or vars().
Assumed instance-only
class C: shared = 1
getattr(C(), "shared")
1 # from the class
Instance-only
vars(C()).get("shared")
None
4. Name is a STRING, not an identifier
A common typo — passing the attribute as if it were a variable. getattr wants the NAME as a string.
Not a string
getattr(obj, upper)
NameError: name 'upper' is not defined
Quote it
getattr(obj, "upper")
bound method

When to use

Use it
  • Attribute access when the name is a runtime STRING
  • Optional attributes with a fallback default
  • Dispatch tables keyed by name — CLI, plugins, factories
  • Method calls via reflection when the method name comes from data
Reach for something else
  • You have a literal attribute name — use dot access directly
  • You want to check existence only → hasattr
  • You want the FULL exception on missing → skip the default and let AttributeError propagate
  • Setting a value → setattr

Notes

Complexity
O(mro depth) — walks the class hierarchy
Return
The attribute value or default; may raise AttributeError
CPython impl
Python/bltinmodule.c :: builtin_getattr — calls PyObject_GetAttr
Memory
No allocation beyond the returned value
Thread-safe
Depends on whether attribute access is safe for the object

FAQ

For a literal attribute name, dot access (obj.name) is identical and clearer. getattr is for when the name is a runtime string — from config, from user input, from a computed value. Also useful for the third-arg default.

History

1.0
getattr() has been a builtin since Python 1.0.
3.2
Only AttributeError is caught internally when computing whether to use the default; other exceptions propagate.