Python How to check if keys exists and retrieve value from Dictionary in descending priority

Question

I have a dictionary and I would like to get some values from it based on some keys  For example  I have a dictionary for users with their first name  last name  username  address  age and so on  Let s say  I only want to get one value  name  - either last name or first name or username but in descending priority like shown below     1  last name  if key exists  get value and stop checking  If not  move to next key    2  first name  if key exists  get value and stop checking  If not  move to next key    3  username  if key exists  get value or return null empty   my dict looks something like this myDict     age     value     address     value1  value2               firstName     value     lastName           List of keys I want to check in descending priority  lastName  gt  firstName  gt  userName keySet     lastName    firstName    userName     What I tried doing is to get all the possible values and put them into a list so I can retrieve the first element in the list  Obviously it didn t work out   tempList       for key in keys      get value   myDict get key      tempList  append get value    Is there a better way to do this without using if else block

User · Answer

Use  get    which if the key is not found  returns None    for i in keySet      temp   myDict get i      if temp is not None          print temp         break

User · Answer

You can use myDict has key keyname  as well to validate if the key exists   Edit based on the comments -  This would work only on versions lower than 3 1  has key has been removed from Python 3 1  You should use the in operator if you are using Python 3 1

User · Answer

If we encapsulate that in a function we could use recursion and state clearly the purpose by naming the function properly  not sure if getAny is actually a good name    def getAny dic  keys  default None       return  keys or default  and dic get keys 0                                             getAny  dic  keys 1    default default     or even better  without recursion and more clear   def getAny dic  keys  default None       for k in keys           if k in dic             return dic k      return default   Then that could be used in a way similar to the dict get method  like   getAny myDict  keySet    and even have a default result in case of no keys found at all   getAny myDict  keySet   not found

User · Answer

One option if the number of keys is small is to use chained gets   value   myDict get  lastName   myDict get  firstName   myDict get  userName       But if you have keySet defined  this might be clearer   value   None for key in keySet      if key in myDict          value   myDict key          break   The chained gets do not short-circuit  so all keys will be checked but only one used  If you have enough possible keys that that matters  use the for loop

[python] Python: How to check if keys exists and retrieve value from Dictionary in descending priority

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