Check if POST exists

Question

I m trying to check whether a   POST exists and if it does  print it inside another string  if not  don t print at all   something like this    fromPerson     from 3A    POST  fromPerson     function fromPerson         if     POST  fromPerson              print          else           print  fromPerson            newString   fromPerson      Any help would be great

User · Answer

Try  if  isset   POST  fromPerson     amp  amp    POST  fromPerson                echo  Cool

User · Answer

I would like to add my answer even though this thread is years old and it ranked high in Google for me   My best method is to try   if sizeof   POST      0      Code        As   POST is an array  if the script loads and no data is present in the   POST variable it will have an array length of 0  This can be used in an IF statement   You may also be wondering if this throws an  undefined index  error seeing as though we re checking if   POST is set    In fact   POST always exists  the  undefined index  error will only appear if you try to search for a   POST array value that doesn t exist     POST always exists in itself being either empty or has array values    POST  value   may not exist  thus throwing an  undefined index  error

User · Answer

Everyone is saying to use isset   - which will probably work for you   However  it s important that you understand the difference between     POST  x     NULL  and   POST  x          isset   POST  x    will return false on the first example  but will return true on the second one even though if you tried to print either one  both would return a blank value   If your   POST is coming from a user-inputted field form and is left blank  I BELIEVE  I am not 100  certain on this though  that the value will be    but NOT NULL   Even if that assumption is incorrect  someone please correct me if I m wrong   the above is still good to know for future use

User · Answer

All the methods are actually discouraged  it s a warning in Netbeans 7 4 and it surely is a good practice not to access superglobal variables directly  use a filter instead   fromPerson   filter input INPUT POST   fromPerson   FILTER DEFAULT   if  fromPerson     NULL       fromPerson is not present     else    present     var dump  fromPerson  exit 0

User · Answer

if  isset   POST  fromPerson      is right   You can use a function and return  better then directing echo

User · Answer

Simple  You ve two choices   1  Check if there s ANY post data at all    Note  This resolves as true even if all   POST values are empty strings if   empty   POST            handle post data      fromPerson     from 3A    POST  fromPerson        echo  fromPerson       OR   2  Only check if a PARTICULAR Key is available in post data  if  isset   POST  fromPerson             fromPerson     from 3A    POST  fromPerson        echo  fromPerson

User · Answer

The proper way of checking if array key exists is function array key exists    The difference is that when you have   POST  variable     null it means that key exists and was send but value was null   The other option is isset   which which will check if array key exists and if it was set  The last option is to use empty   which will check if array key exists if is set and if value is not considered empty   Examples    arr        a    gt  null     b    gt         c    gt  1     array key exists  a    arr      true isset  arr  a        false empty  arr  a        true   array key exists  b    arr      true isset  arr  b        true empty  arr  b        true   array key exists  c    arr      true isset  arr  c        true empty  arr  c        false   Regarding your question  The proper way to check if value was send is to use array key exists   with check of request method  if    SERVER  REQUEST METHOD       POST   amp  amp  array key exists  fromPerson     POST              logic     But there are some cases depends on your logic where isset   and empty   can be good as well

User · Answer

isset   POST  fromPerson

User · Answer

if  is array   POST   amp  amp  array key exists  fromPerson     POST         echo  blah      POST  fromPerson

User · Answer

In that case using method isset is not appropriate    According to PHP documentation  http   php net manual en function array-key-exists php  see Example  2  array key exists   vs isset    The method array key exists is intended for checking key presence in array   So code in the question could be changed as follow   function fromPerson        if  array key exists  fromPerson     POST     FALSE            return          else           return   from 3A    POST  fromPerson              newString   fromPerson         Checking presence of array   POST is not necessary because it is PHP environment global variable since version 4 1 0  nowadays we does not meet older versions of PHP

User · Answer

Try isset   POST  fromPerson

User · Answer

Surprised it has not been mentioned  if   SERVER  REQUEST METHOD       POST   amp  amp  isset   POST  fromPerson

User · Answer

if  isset   POST  fromPerson              fromPerson     from 3A    POST  fromPerson         echo  fromPerson

User · Answer

I like to check if it isset and if it s empty in a ternary operator       POST variable check  userID     isset    POST  userID         amp  amp   empty    POST  userID            POST  userID        null   line       isset    POST  line           amp  amp   empty    POST  line              POST  line          null   message    isset    POST  message        amp  amp   empty    POST  message           POST  message       null   source     isset    POST  source         amp  amp   empty    POST  source            POST  source        null   version    isset    POST  version        amp  amp   empty    POST  version           POST  version       null   release    isset    POST  release        amp  amp   empty    POST  release           POST  release       null

[php] Check if $_POST exists

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