PHP Make a simple if-isset-empty function

问题

I'm coding a worksheet app for a printer company. I'm getting flood of forms. For every single input field I have to check if the $_POST variables are set, and if, so echo back the value. (In case of some error, for example after a validation error, the user shouldn't retype the whole form)

Sample code:

if(isset($_POST['time'])&&!empty($_POST['time'])){echo $_POST['time'];}

I had to implement this about a hundred times. So I tried to figure out some kind of function to make this simple and readable.

Something like this:

function if_post_echo($key, $default = "") {
    if(isset($_POST[$key])&&!empty($_POST[$key])){
    echo $_POST[$key];   
    }else{
    echo $default;   
    }
}

But this wont work. I have tried to pass in the $_POST for the $key variable like this:

if_post_echo($_POST['time'])

function if_request_echo($key, $default = "") {
        if(isset($key)&&!empty($key)){
        echo $key;   
        }else{
        echo $default;   
        }
    }

And I also tried this:

function if_request_echo($key, $default = null) {
    return isset($_REQUEST[$key])&&!empty($_REQUEST[$key]) ? $_REQUEST[$key] : $default;
}

Without any reasonable outcome.

The question:

How can I forge a function that looks for the necessary $_POST variable and returns it or if its unset then returns an empty string. And is there a way to do this for $_GET and $_REQUEST, too? (Or simply duplicate?)

回答1:

Your PHP testing function:

<?php
function test_req($key, $default = '') {
    if(isset($_REQUEST[$key]) and
       !empty($_REQUEST[$key])) {
        return $_REQUEST[$key];
    } else {
        return $default;
    }
}
?>

Then in your form HTML:

<input name="my_field" value="<?php echo htmlentities(test_req('my_field')); ?>" />

$_REQUEST (linked) is a PHP super global that contains both POST ($_POST) and GET ($_GET) request parameters.

If you only want to capture POST request parameters then it would be:

<?php
function test_req($key, $default = '') {
    if(isset($_POST[$key]) and
       !empty($_POST[$key])) {
        return $_POST[$key];
    } else {
        return $default;
    }
}
?>

For example.

回答2:

If you have a large amount of fields, I would propose that you also use an array of defaults:

$defaults = array(
    "time" => "default",
    "name" => "enter name here",
    "text..." => "...",
);

$fields = array_filter($_POST) + $defaults;

$fields will then contain a list of form values with either the POST data or a preset default. No isset, see?

array_filter man page particularly: If no callback is supplied, all entries of input equal to FALSE will be removed. Goes some way to explaining the working behind this solution.

回答3:

This should work:

function if_post_echo($key, $default = ''){
    if(isset($_POST[$key]) AND !empty($_POST[$key]){
        echo $_POST[$key];
    }

    echo $default;
}

If you're having problems I recommend that you try var_dump($_POST) or print_r($_POST) to see if everything has been properly posted.

回答4:

Just to note, this is redundant:

isset($_POST[$key]) && !empty($_POST[$key])

An unset variable is going to always be "empty", so isset() is implied in your empty() call.

For your logic you can achieve the same result with just:

!empty($_POST[$key])

回答5:

Your first function works perfectly to me.

Why do you think it doesn't work?

However, a better variant would be

function _post($key, $default = "") {
    if(isset($_POST[$key])){
        return $_POST[$key];
    }else{
        return $default;
    }
}

To use it :

echo $_post($key); // You could define the message as a second parameter.

回答6:

function requireArray( $array, $required ) {
    foreach( $required as $k=>$v ) {
        if ( !isset($array[$k]) || empty($array[$k]) )
            return false;
    }
    return true;
}
#call like this:
requireArray($_POST, array('time', 'username', 'foo'));

If you want to know specifically:

function missingFrom( $array, $required ) {
    $r = array();
    foreach( $required as $k ) {
        if ( !isset($array[$k]) || empty($array[$k]) )
            $r[] = $k;
    }
    return $r;
}

Called like previous function.

回答7:

Your method seems to work fine here:

function if_post_echo($key, $default = "") {
    if(isset($_POST[$key])&&!empty($_POST[$key])){
        echo $_POST[$key];   
    }else{
        echo $default;   
    }
}

I made a simple input with the name test and the form method is POST and using echo if_post_echo('test');.

It posted on the page what was in the text box.