List attributes of an object

Question

Is there a way to grab a list of attributes that exist on instances of a class   class new class        def   init   self  number           self multi   int number    2         self str   str number   a   new class 2  print      join a SOMETHING     The desired result is that  multi  str  will be output   I want this to see the current attributes from various parts of a script

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gt  gt  gt  class new class          def   init   self  number           self multi   int number    2         self str   str number        gt  gt  gt  a   new class 2   gt  gt  gt  a   dict     multi   4   str    2    gt  gt  gt  a   dict   keys   dict keys   multi    str      You may also find pprint helpful

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attributes list    attribute for attribute in dir obj  if attribute 0  islower

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vars obj  returns the attributes of an object

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You can use dir your object  to get the attributes and getattr your object  your object attr  to get the values  usage    for att in dir your object       print  att  getattr your object att     This is particularly useful if your object have no   dict    If that is not the case you can try var your object  also

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attrs   gives the list of attributes of an instance   gt  gt  gt  import requests  gt  gt  gt  r requests get  http   www google com    gt  gt  gt  r   attrs      content    status code    headers    url    history    encoding    reason    cookies    elapsed    request    gt  gt  gt  r url  http   www google com    gt  gt  gt

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There is more than one way to do it       usr bin env python3     This demonstrates how to pick the attiributes of an object  class C object       def   init    self  name  q         self q   name     self m    y    c   C    print   dir c      When run  this code produces   jeffs jeff-desktop   skyset  python3 attributes py      class        delattr        dict        dir        doc             eq        format        ge        getattribute        gt        hash        init        le        lt        module        ne        new        reduce        reduce ex        repr        setattr        sizeof        str        subclasshook        weakref      m    q    jeffs jeff-desktop   skyset

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dir instance    or  same value  instance   dir       or instance   dict     Then you can test what type is with type   or if is a method with callable

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What do you want this for  It may be hard to get you the best answer without knowing your exact intent    It is almost always better to do this manually if you want to display an instance of your class in a specific way  This will include exactly what you want and not include what you don t want  and the order will be predictable    If you are looking for a way to display the content of a class  manually format the attributes you care about and provide this as the   str   or   repr   method for your class  If you want to learn about what methods and such exist for an object to understand how it works  use help  help a  will show you a formatted output about the object s class based on its docstrings  dir exists for programatically getting all the attributes of an object   Accessing   dict   does something I would group as the same but that I wouldn t use myself   However  this may not include things you want and it may include things you do not want  It is unreliable and people think they want it a lot more often than they do  On a somewhat orthogonal note  there is very little support for Python 3 at the current time  If you are interested in writing real software you are going to want third-party stuff like numpy  lxml  Twisted  PIL  or any number of web frameworks that do not yet support Python 3 and do not have plans to any time too soon  The differences between 2 6 and the 3 x branch are small  but the difference in library support is huge

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Get  attributes of an object  class new class        def   init   self  number       self multi   int number    2     self str   str number   new object   new class 2                  print dir new object                      total list attributes of new object attr value   new object   dict            print attr value                          Dictionary of attribute and value for new class                     for attr in attr value                    attributes on  new class     print attr     Output      class        delattr        dict        dir        doc       eq        format        ge        getattribute        gt        hash        init        init subclass        le        lt        module        ne        new        reduce        reduce ex        repr        setattr        sizeof        str        subclasshook        weakref      multi    str      multi   4   str    2    multi str

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gt  gt  gt       join i for i in dir a  if not i startswith         multi  str    This of course will print any methods or attributes in the class definition  You can exclude  private  methods by changing i startwith       to i startwith

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Using   dict   or vars does not work because it misses out   slots    Using   dict   and   slots   does not work because it misses out   slots   from base classes  Using dir does not work because it includes class attributes  such as methods or properties  as well as the object attributes  Using vars is equivalent to using   dict      This is the best I have   from typing import Dict  def get attrs  x   object   - gt  Dict str  object       mro        type  x   mro       attrs              has dict   False     sentinel   object        for klass in mro          for slot in getattr  klass     slots                       v   getattr  x  slot  sentinel                if v is sentinel                  continue              if slot       dict                     assert not has dict   Multiple   dicts                     attrs update  v                   has dict   True             else                  attrs slot    v      if not has dict          attrs update  getattr  x     dict                  return attrs

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Inspect module   The inspect module provides several useful functions to help get information about live objects such as modules  classes  methods  functions  tracebacks  frame objects  and code objects    Using getmembers   you can see all attributes of your class  along with their value  To exclude private or protected attributes use  startswith       To exclude methods or functions use inspect ismethod   or inspect isfunction    import inspect   class NewClass object       def   init   self  number           self multi   int number    2         self str   str number       def func 1 self           pass   a   NewClass 2   for i in inspect getmembers a         Ignores anything starting with underscore         that is  private and protected attributes      if not i 0  startswith                 Ignores methods         if not inspect ismethod i 1                print i   Note that ismethod   is used on the second element of i since the first is simply a string  its name   Offtopic  Use CamelCase for class names

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In addition to these answers  I ll include a function  python 3  for spewing out virtually the entire structure of any value  It uses dir to establish the full list of property names  then uses getattr with each name  It displays the type of every member of the value  and when possible also displays the entire member   import json  def get info obj      type name   type obj    name     print  Value is of type      format type name     prop names   dir obj     for prop name in prop names      prop val   getattr obj  prop name      prop val type name   type prop val    name       print     has property      of type       format type name  prop name  prop val type name        try        val as str   json dumps   prop val    indent 2  1 -1        print    Here  s the    value      format prop name  val as str       except        pass   Now any of the following should give insight    get info None  get info  hello    import numpy get info numpy        etc

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Please see the python shell script which has been executed in sequence  here you will get the attributes of a class in string format separated by comma    gt  gt  gt  class new class            def   init   self  number               self multi   int number  2             self str   str number        gt  gt  gt  a   new class 4   gt  gt  gt      join a   dict   keys     str multi  lt br  gt    I am using python 3 4

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All previous answers are correct  you have three options for what you are asking    dir   vars     dict      gt  gt  gt  dir a      class        delattr        dict        dir        doc        eq        format        ge        getattribute        gt        hash        init        init subclass        le        lt        module        ne        new        reduce        reduce ex        repr        setattr        sizeof        str        subclasshook        weakref      multi    str    gt  gt  gt  vars a    multi   4   str    2    gt  gt  gt  a   dict     multi   4   str    2

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As written before using obj   dict   can handle common cases but some classes do not have the   dict   attribute and use   slots    mostly for memory efficiency    example for a more resilient way of doing this   class A object         slots       x    y         def   init   self  x  y           self x   x         self y   y   class B object       def   init   self  x  y           self x   x         self y   y   def get object attrs obj       try          return obj   dict       except AttributeError          return  attr  getattr obj  attr  for attr in obj   slots      a   A 1 2  b   B 1 2  assert not hasattr a     dict      print get object attrs a   print get object attrs b     this code s output     x   1   y   2    x   1   y   2    Note1  Python is a dynamic language and it is always better knowing the classes you trying to get the attributes from as even this code can miss some cases   Note2  this code outputs only instance variables meaning class variables are not provided  for example   class A object       url    http   stackoverflow com      def   init   self  path           self path   path  print A   questions     dict      code outputs     path     questions     This code does not print the url class attribute and might omit wanted class attributes  Sometimes we might think an attribute is an instance member but it is not and won t be shown using this example

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It s often mentioned that to list a complete list of attributes you should use dir    Note however that contrary to popular belief dir   does not bring out all attributes  For example you might notice that   name   might be missing from a class s dir   listing even though you can access it from the class itself  From the doc on dir    Python 2  Python 3       Because dir   is supplied primarily as a convenience for use at an   interactive prompt  it tries to supply an interesting set of names   more than it tries to supply a rigorously or consistently defined set   of names  and its detailed behavior may change across releases  For   example  metaclass attributes are not in the result list when the   argument is a class    A function like the following tends to be more complete  although there s no guarantee of completeness since the list returned by dir   can be affected by many factors including implementing the   dir     method  or customizing   getattr     or   getattribute     on the class or one of its parents  See provided links for more details   def dirmore instance       visible   dir instance      visible     a for a in set dir type   difference visible                  if hasattr instance  a       return sorted visible

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Please see the following Python shell scripting execution in sequence  it will give the solution from creation of class to extracting the field names of instances    gt  gt  gt  class Details            def   init   self name age                 self name name               self age  age           def show details self                 if self name                   print  Name     self name               else                   print  Name                       if self age                   if self age gt 0                      print  Age      self age                  else                      print  Age can t be -ve                else                   print  Age                gt  gt  gt  my details   Details  Rishikesh  24   gt  gt  gt    gt  gt  gt  print my details  lt   main   Details instance at 0x10e2e77e8 gt   gt  gt  gt    gt  gt  gt  print my details name Rishikesh  gt  gt  gt  print my details age 24  gt  gt  gt    gt  gt  gt  my details show details   Name    Rishikesh Age     24  gt  gt  gt    gt  gt  gt  person1   Details    34   gt  gt  gt  person1 name     gt  gt  gt  person1 age 34  gt  gt  gt  person1 show details  lt bound method Details show details of  lt   main   Details instance at 0x10e2e7758 gt  gt   gt  gt  gt    gt  gt  gt  person1 show details   Name      Age     34  gt  gt  gt   gt  gt  gt  person2   Details  Rob Pike  0   gt  gt  gt  person2 name  Rob Pike   gt  gt  gt    gt  gt  gt  person2 age 0  gt  gt  gt    gt  gt  gt  person2 show details   Name    Rob Pike Age        gt  gt  gt    gt  gt  gt  person3   Details  Rob Pike  -45   gt  gt  gt    gt  gt  gt  person3 name  Rob Pike   gt  gt  gt    gt  gt  gt  person3 age -45  gt  gt  gt    gt  gt  gt  person3 show details   Name    Rob Pike Age can t be -ve  gt  gt  gt   gt  gt  gt  person3   dict     age   -45   name    Rob Pike    gt  gt  gt   gt  gt  gt  person3   dict   keys     age    name    gt  gt  gt   gt  gt  gt  person3   dict   values    -45   Rob Pike    gt  gt  gt

[python] List attributes of an object

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