Check whether POST-value is empty

Question

if isset   POST  submit           if  isset   POST  userName                username    Anonymous                   else  username     POST  userName        I cannot get the  username to be  Anonymous   It is either blank or the value of    POST  userName

User · Answer

isset is testing whether or not the key you are checking in the hash (or associative array) is "set". Set in this context just means if it knows the value. Nothing is a value. So it is defined as being an empty string.

For that reason, as long as you have an input field named userName, regardless of if they fill it in, this will be true. What you really want to do is check if the userName is equal to an empty string ''

User · Answer

i d use a simple one line comparisant for these use cases   username   trim   POST  userName      Anonymous     This is for the use case you are certain error logging is off so you don t get a warning that the variable isn t initialised   this is the paranoid version    username    empty trim isset   POST  userName      POST  userName          POST  userName    Anonymous     This implements a check if the   POST variable is set  before accessing it

User · Answer

Change this   if isset   POST  submit           if   isset   POST  userName            username    Anonymous                   else  username     POST  userName        To this   if  empty   POST  userName            username     POST  userName       if empty   POST  userName            username    Anonymous

User · Answer

To check if the property is present  irrespective of the value  use   if  array key exists  userName     POST        To check if the property is set  property is present and value is not null or false   use   if  isset   POST  userName          To check if the property is set and not empty  not an empty string  0  integer   0 0  float    0   string   null  false or     empty array    use   if   empty   POST  userName

User · Answer

If the form was successfully submitted    POST  userName   should always be set  though it may contain an empty string  which is different from not being set at all  Instead check if it is empty    if  isset   POST  submit           if  empty   POST  userName                username    Anonymous         else             username     POST  userName

User · Answer

isset   will return true if the variable has been initialised  If you have a form field with its name value set to userName  when that form is submitted the value will always be  set   although there may not be any data in it   Instead  trim   the string and test its length  if       trim   POST  userName           username    Anonymous

User · Answer

Question  Check whether a   POST value is empty  Translation  Check to see if an array key index has a value associated with it  Answer  Depends on your emphasis on security  Depends on what is allowed as valid input  1  Some people say use empty     From the PHP Manual    quot  Empty  determines whether a variable is considered to be empty  A variable is considered empty if it does not exist or if its value equals FALSE  quot   The following are thus considered empty   quot  quot   an empty string  0  0 as an integer  0 0  0 as a float   quot 0 quot   0 as a string  NULL FALSE array    an empty array   var   a variable declared  but without a value   If none of these values are valid for your input control  then empty   would work  The problem here is that empty   might be too broad to be used consistently  the same way  for the same reason  on different input control submissions to   POST or   GET   A good use of empty   is to check if an entire array is empty  has no elements   2  Some people say use isset     isset    a language construct  cannot operate on entire arrays  as in isset  myArray   It can only operate on variables and array elements  via the index key   isset  var  and isset   POST  username     The isset  language construct does two things  First it checks to see if a variable or array index key has a value associated with it  Second  it checks to make sure that value is not equal to the PHP NULL value  In short  the most accurate check can be accomplished best with isset    as some input controls do not even register with   POST when they are not selected or checked  I have never known a form that submitted the PHP NULL value  None of mine do  so I use isset   to check if a   POST key has no value associated with it  and that is not NULL   isset  is a much stricter test of emptiness  in the sense of your question  than empty    3  Some people say just do if  var   if  myArray   or if  myArray  userName    to determine emptiness    You can test anything that evaluates to true or false in an if statement  Empty arrays evaluate to false and so do variables that are not set  Variables that contain the PHP NULL value also evaluate to false  Unfortunately in this case  like with empty    many more things also  evaluate to false  1  the empty string     zero  0   zero zero  0 0   the string zero  0   boolean false  and certain empty XML objects  --Doyle  Beginning PHP 5 3  In conclusion  use isset   and consider combining it with other tests  Example  May not work due to superglobal screwiness  but would work for other arrays without question  if  is array   POST   amp  amp   empty   POST            Now test for your successful controls in   POST with isset       Hence  why look for a value associated with a key before you even know for sure that   POST represents an array and has any values stored in it at all  something many people fail to consider   Remember  people can send data to your form without using a web browser  You may one day get to the point of testing that   POST only has the allowed keys  but that conversation is for another day  Useful reference  PHP Manual  Type Testing Comparison Tables

User · Answer

username   filter input INPUT POST   userName   FILTER SANITIZE STRING   if   username          username    Anonymous      Best practice - always filter inputs  sanitize string is ok  but you re better off using a custom callback function to really filter out what s not acceptable  Then check the now-safe variable if it is null empty and if it is  set to Anonymous   Does not require  else  statement as it was set if it existed on the first line

[php] Check whether $_POST-value is empty

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