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Convert string to Python class object?

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python

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How do you convert a string to a Class object in Python?

Use the json.loads() function. The json. loads() function accepts as input a valid string and converts it to a Python dictionary. This process is called deserialization – the act of converting a string to an object.

How do you make a string object in Python?

To create a string, put the sequence of characters inside either single quotes, double quotes, or triple quotes and then assign it to a variable. You can look into how variables work in Python in the Python variables tutorial. For example, you can assign a character 'a' to a variable single_quote_character .

Which function convert a string to an object in Python?

1 Answer. The answer is option D (str(x)). str(x) converts the object to a string in python.


This could work:

import sys

def str_to_class(classname):
    return getattr(sys.modules[__name__], classname)

Warning: eval() can be used to execute arbitrary Python code. You should never use eval() with untrusted strings. (See Security of Python's eval() on untrusted strings?)

This seems simplest.

>>> class Foo(object):
...     pass
... 
>>> eval("Foo")
<class '__main__.Foo'>

You could do something like:

globals()[class_name]

You want the class Baz, which lives in module foo.bar. With Python 2.7, you want to use importlib.import_module(), as this will make transitioning to Python 3 easier:

import importlib

def class_for_name(module_name, class_name):
    # load the module, will raise ImportError if module cannot be loaded
    m = importlib.import_module(module_name)
    # get the class, will raise AttributeError if class cannot be found
    c = getattr(m, class_name)
    return c

With Python < 2.7:

def class_for_name(module_name, class_name):
    # load the module, will raise ImportError if module cannot be loaded
    m = __import__(module_name, globals(), locals(), class_name)
    # get the class, will raise AttributeError if class cannot be found
    c = getattr(m, class_name)
    return c

Use:

loaded_class = class_for_name('foo.bar', 'Baz')

I've looked at how django handles this

django.utils.module_loading has this

def import_string(dotted_path):
    """
    Import a dotted module path and return the attribute/class designated by the
    last name in the path. Raise ImportError if the import failed.
    """
    try:
        module_path, class_name = dotted_path.rsplit('.', 1)
    except ValueError:
        msg = "%s doesn't look like a module path" % dotted_path
        six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])

    module = import_module(module_path)

    try:
        return getattr(module, class_name)
    except AttributeError:
        msg = 'Module "%s" does not define a "%s" attribute/class' % (
            module_path, class_name)
        six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])

You can use it like import_string("module_path.to.all.the.way.to.your_class")