How to enumerate an object s properties in Python

Question

I C  we do it through reflection  In Javascript it is simple as   for var propertyName in objectName      var currentPropertyValue   objectName propertyName     How to do it in Python

User · Answer

for one-liners  print vars theObject

User · Answer

The   dict   property of the object is a dictionary of all its other defined properties  Note that Python classes can override getattr and make things that look like properties but are not in  dict    There s also the builtin functions vars   and dir   which are different in subtle ways  And   slots   can replace   dict   in some unusual classes   Objects are complicated in Python    dict   is the right place to start for reflection-style programming  dir   is the place to start if you re hacking around in an interactive shell

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for property  value in vars theObject  items        print property   quot   quot   value   Be aware that in some rare cases there s a   slots   property  such classes often have no   dict

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This is totally covered by the other answers  but I ll make it explicit  An object may have class attributes and static and dynamic instance attributes   class foo      classy   1      property     def dyno self           return 1     def   init   self           self stasis   2      def fx self           return 3   stasis is static  dyno is dynamic  cf  property decorator  and classy is a class attribute  If we simply do   dict   or vars we will only get the static one   o   foo   print o   dict       stasis   2  print vars o      stasis   2    So if we want the others   dict   will get everything  and more   This includes magic methods and attributes and normal bound methods  So lets avoid those   d    k  getattr o  k      for k in o   dir     if k  2          and type getattr o  k         name       method   print d     stasis   2   classy   1   dyno   1    The type called with a property decorated method  a dynamic attribute  will give you the type of the returned value  not method  To prove this let s json stringify it   import json print json dumps d      stasis   2   classy   1   dyno   1    Had it been a method it would have crashed   TL DR  try calling extravar   lambda o   k  getattr o  k      for k in o   dir     if k  2          and type getattr o  k         name       method   for all three  but not methods nor magic

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I think it s worth showing the difference between the various options mentioned - often a picture is worth a thousand words   gt  gt  gt  from pprint import pprint  gt  gt  gt  import inspect  gt  gt  gt   gt  gt  gt  class a        x   1                 static class member     def   init   self           self y   2        static instance member      property     def dyn prop self     dynamic property         print  DYNPROP WAS HERE           return 3     def test self         function member         pass      classmethod     def myclassmethod cls     class method  static methods behave the same         pass   gt  gt  gt  i   a    gt  gt  gt  pprint i   dict      y   2   gt  gt  gt  pprint vars i     y   2   gt  gt  gt  pprint dir i       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       dyn prop     myclassmethod     test     x     y    gt  gt  gt  pprint inspect getmembers i   DYNPROP WAS HERE      class      lt class    main   a  gt         delattr        lt method-wrapper    delattr    of a object at 0x000001CB891BC7F0 gt         dict       y   2         dir      lt built-in method   dir   of a object at 0x000001CB891BC7F0 gt         doc     None        eq      lt method-wrapper    eq    of a object at 0x000001CB891BC7F0 gt         format      lt built-in method   format   of a object at 0x000001CB891BC7F0 gt         ge      lt method-wrapper    ge    of a object at 0x000001CB891BC7F0 gt         getattribute        lt method-wrapper    getattribute    of a object at 0x000001CB891BC7F0 gt         gt      lt method-wrapper    gt    of a object at 0x000001CB891BC7F0 gt         hash      lt method-wrapper    hash    of a object at 0x000001CB891BC7F0 gt         init        lt bound method a   init   of  lt   main   a object at 0x000001CB891BC7F0 gt  gt         init subclass        lt built-in method   init subclass   of type object at 0x000001CB87CA6A70 gt         le      lt method-wrapper    le    of a object at 0x000001CB891BC7F0 gt         lt      lt method-wrapper    lt    of a object at 0x000001CB891BC7F0 gt         module        main           ne      lt method-wrapper    ne    of a object at 0x000001CB891BC7F0 gt         new      lt built-in method   new   of type object at 0x00007FFCA630AB50 gt         reduce      lt built-in method   reduce   of a object at 0x000001CB891BC7F0 gt         reduce ex        lt built-in method   reduce ex   of a object at 0x000001CB891BC7F0 gt         repr      lt method-wrapper    repr    of a object at 0x000001CB891BC7F0 gt         setattr        lt method-wrapper    setattr    of a object at 0x000001CB891BC7F0 gt         sizeof      lt built-in method   sizeof   of a object at 0x000001CB891BC7F0 gt         str      lt method-wrapper    str    of a object at 0x000001CB891BC7F0 gt         subclasshook        lt built-in method   subclasshook   of type object at 0x000001CB87CA6A70 gt         weakref     None      dyn prop   3      myclassmethod    lt bound method a myclassmethod of  lt class    main   a  gt  gt       test    lt bound method a test of  lt   main   a object at 0x000001CB891BC7F0 gt  gt       x   1      y   2    To summarize   vars   and   dict   only return instance-local properties  dir   returns everything  but only as a list of string member names  dynamic properties are not called  inspect getmembers   returns everything  as a list of tuples  name  value   it actually runs dynamic properties  and accepts an optional predicate argument that can filter out members by value   So my common-sense approach is typically to use dir   on the command line  and getmembers   in programs  unless specific performance considerations apply  Note that  to keep things cleaner  I did not include   slots   - if present  it was explicitly put there to be queried  and should be used directly  I also did not cover metaclasses  which can get a bit hairy  most people will never use them anyway

User · Answer

See inspect getmembers object   predicate        Return all the members of an object in a list of  name  value  pairs sorted by name  If the optional predicate argument is supplied  only members for which the predicate returns a true value are included     gt  gt  gt   name for name thing in inspect getmembers          add        class        contains        delattr        delitem         delslice           doc        eq        format        ge        getattribute         getitem        getslice        gt        hash        iadd        imul        init        iter         le        len        lt        mul        ne        new        reduce       reduce ex         repr        reversed        rmul        setattr        setitem        setslice         sizeof        str        subclasshook      append    count    extend    index     insert    pop    remove    reverse    sort    gt  gt  gt

User · Answer

dir   is the simple way  See here   Guide To Python Introspection

User · Answer

If you re looking for reflection of all properties  the answers above are great   If you re simply looking to get the keys of a dictionary  which is different from an  object  in Python   use  my dict keys    my dict     abc        def   12   ghi    string    my dict keys     gt    abc    def    ghi

[python] How to enumerate an object's properties in Python?

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