PHP check whether property exists in object or class

Question

I understand PHP does not have a pure object variable  but I want to check whether a property is in the given object or class    ob    object  array  a    gt  1   b    gt  12      or   ob   new stdClass   ob- gt a   1   ob- gt b   2    In JS  I can write this to check if variable a exists in an object   if   a  in ob    In PHP  can anything like this be done   Thank you very much for your advice

User · Answer

To check if something exits  you can use the PHP function isset   see php net  This function will check if the variable is set and is not NULL   Example    if isset  obj- gt a          do something     If you need to check if a property exists in a class  then you can use the build in function property exists    Example   if  property exists  class    property           do something

User · Answer

To check if the property exists and if it s null too  you can use the function property exists      Docs  http   php net manual en function property-exists php  As opposed with isset    property exists   returns TRUE even if the property has the value NULL      bool property exists   mixed  class   string  property     Example   if  property exists  testObject   property           do something

User · Answer

Solution  echo  person- gt middleName     Person does not have a middle name    To show how this would look in an if statement for more clarity on how this is working   if  person- gt middleName    false        echo  person- gt middleName    else       echo  Person does not have a middle name       Explanation  The traditional PHP way to check for something s existence is to do   if isset  person- gt middleName         echo  person- gt middleName    else       echo  Person does not have a middle name       OR for a more class specific way   if property exists  person   middleName          echo  person- gt middleName    else       echo  Person does not have a middle name       These are both fine in long form statements but in ternary statements they become unnecessarily cumbersome like so   isset  person- gt middleName    echo  person- gt middleName   echo  Person does not have a middle name    You can also achieve this with just the ternary operator like so   echo  person- gt middleName     Person does not have a middle name     But    if the value does not exist  is not set  it will raise an E NOTICE and is not best practise  If the value is null it will not raise the exception   Therefore ternary operator to the rescue making this a neat little answer   echo  person- gt middleName     Person does not have a middle name

User · Answer

Just putting my 2 cents here   Given the following class   class Foo     private  data     public function   construct array  data           this- gt data    data         public function   get  name          return  data  name          public function   isset  name          return array key exists  name   this- gt data           the following will happen    foo   new Foo   key    gt   value    bar    gt  null     var dump property exists  foo   key         false var dump isset  foo- gt key        true var dump property exists  foo   bar         false var dump isset  foo- gt bar        true  although  data  bar      null   Hope this will help anyone

User · Answer

If you want to know if a property exists in an instance of a class that you have defined  simply combine property exists   with isset     public function hasProperty  property        return property exists  this   property   amp  amp  isset  this- gt  property

User · Answer

Using array key exists   on objects is Deprecated in php 7 4  Instead either isset   or property exists   should be used  reference   php net

User · Answer

Neither isset or property exists work for me    isset returns false if the property exists but is NULL  property exists returns true if the property is part of the object s class definition  even if it has been unset    I ended up going with        exists   array key exists  property  get object vars  obj      Example       class Foo           public  bar           function   construct                  property    bar                isset  this- gt  property      FALSE             property exists  this   property      TRUE             array key exists  property  get object vars  this       TRUE              unset  this- gt  property                isset  this- gt  property      FALSE             property exists  this   property      TRUE             array key exists  property  get object vars  this       FALSE               this- gt  property    baz                isset  this- gt  property      TRUE             property exists  this   property      TRUE             array key exists  property  get object vars  this        TRUE

User · Answer

property exists  mixed  class   string  property    if  property exists  ob   a       isset  mixed  var    mixed           if  isset  ob- gt a        isset   will return false if property is null   Example 1    ob- gt a   null var dump isset  ob- gt a       false   Example 2    class Foo      public  bar   null      foo   new Foo     var dump property exists  foo   bar        true var dump isset  foo- gt bar       false

[php] PHP check whether property exists in object or class

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