Check if $_POST exists

Question 1

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!

Question 2

if( isset($_POST['fromPerson']) )
{
     $fromPerson = '+from%3A'.$_POST['fromPerson'];
     echo $fromPerson;
}

Question 3

Here's what worked best for me when trying to script this (in case anyone else comes across this like I did):

$ pecl -d php_suffix=5.6 install <package>
$ pecl uninstall -r <package>

$ pecl -d php_suffix=7.0 install <package>
$ pecl uninstall -r <package>

$ pecl -d php_suffix=7.1 install <package>
$ pecl uninstall -r <package>

The -d php_suffix=<version> piece allows you to set config values at run time vs pre-setting them with pecl config-set. The uninstall -r bit does not actually uninstall it (from the docs):

vagrant@homestead:~$ pecl help uninstall
pecl uninstall [options] [channel/]<package> ...
Uninstalls one or more PEAR packages.  More than one package may be
specified at once.  Prefix with channel name to uninstall from a
channel not in your default channel (pecl.php.net)

Options:
  ...
  -r, --register-only
        do not remove files, only register the packages as not installed
  ...

The uninstall line is necessary otherwise installing it will remove any previously installed version, even if it was for a different PHP version (ex: Installing an extension for PHP 7.0 would remove the 5.6 version if the package was still registered as installed).

Question 4

Your checkData.php script is returning a Boolean value (true or false) but it is not returning a complete HTTP response. Your script should return a complete HTTP response, and encode the results in something like JSON format, like this:

$data = [ 'exists' =>
  (fopen($cat1,"r") || fopen($cat2,"r"))
];
header('Content-Type: application/json');
echo json_encode($data);

Then, your JS .done() function should parse the returned JSON response, examine the value returned by the server, and respond accordingly, like this:

done(function(data){
  if (data.exists) { // 'exists' is the key returned by PHP
    console.log('The file exists!');
  } else {
    console.log('The file does NOT exist!');
  }
}

Question 5

There are at least two problems in this code:

the first one is linked to Javascript closure management. The body of a loop does not create a scope. With Javascript, scope of variables is at function level, not block level. You need to introduce some function in the loop itself to enforce the creation of a proper closure. More information here.
the second one is a race condition between the exists and set commands. If you have several Redis connections running exists and set commands on the same keys, you will likely have some kind of conflicts. Instead of using exists and set, you should use setnx which perform the check and set in one atomic operation.

Considering your second example, the closure problem has been fixed by using forEach, but you still generate all the get operations before the set operations due to the asynchronous nature of the language.

If you really want to sequence all your get and set operations (which will be much slower btw), then you can use a bit of functional programming to implement the loop using recursion.

Example:

This program:

var redis = require('redis')
var rc = redis.createClient(6379, 'localhost');

var tags = [
  "apple",
  "tiger",
  "mouse",
  "apple",
  "apple",
  "apple",
  "tiger",
  "mouse",
  "mouse",
];

var count = 0;

function loop(tags) {
  function rec_loop(tags,i) {
     if ( i >= tags.length )
        return
     rc.get("tag:"+tags[i],function(err,rr) {
        console.log("get tag "+tags[i]+" result code "+rr);
        if ( rr == null ) {
           rc.set("tag:"+tags[i],"info",function(err,rr) {
              count++;
              console.log('set tag '+tags[i]+' '+rr+' objects count '+count);
              rec_loop(tags,++i)
           })
        } else
          rec_loop(tags,++i)
     })
  }
  rec_loop(tags,0)
}

loop(tags)

displays:

get tag apple result code null
set tag apple OK objects count 1
get tag tiger result code null
set tag tiger OK objects count 2
get tag mouse result code null
set tag mouse OK objects count 3
get tag apple result code info
get tag apple result code info
get tag apple result code info
get tag tiger result code info
get tag mouse result code info
get tag mouse result code info

Note that the race condition is still present in this example. You are supposed to use setnx to implement this kind of check and set operations.

Question 6

Never used any of those, but they look interesting..

Take a look at Gearman as well.. more overhead in systems like these but you get other cool stuff :) Guess it depends on your needs ..

Check if $_POST exists

Answers

php