I have a recursive array depth of which is variable, and I want to be able to take a string with a separator and convert that string to an index in that array,
For example
$path = 'level1.level2.level3';
will be converted to get the value 'my data' from the array below
$data['level1']['level2']['level3'] = 'my data';
I thought the quickest way to get this would be to use variable variables, but when I try the following code
$index = "data['level1']['level2']['level3']";
echo $$index;
I get the follwing error
PHP Notice: Undefined variable: data['level1']['level2']['level3']
All other ways I can think of doing this are very inefficient, could someone please shed some light on this, is it possible using variable variables for arrays in PHP? Any other efficient workaround?
Many thanks.
You'll have to loop the array, you won't manage to do this using variable variables, as far as I know. This seems to work though:
<?php
function retrieve( $array, $path ) {
$current = $array;
foreach( explode( '.', $path ) as $segment ) {
if( false === array_key_exists( $segment, $current ) ) {
return false;
}
$current = $current[$segment];
}
return $current;
}
$path = 'level1.level2.level3';
// will be converted to get the value 'my data' from the array below
$data['level1']['level2']['level3'] = 'my data';
var_dump( retrieve( $data, $path ) );
It is a tricky one this, here is the most efficient way I can think of:
function get_value_from_array ($array, $path, $pathSep = '.') {
foreach (explode($pathSep, $path) as $pathPart) {
if (isset($array[$pathPart])) {
$array = $array[$pathPart];
} else {
return FALSE;
}
}
return $array;
}
Returns the value, or FALSE on failure.
Try
$index = "data";
echo $$index['level1']['level2']['level3'];
instead, because $index should be only variable name
Something like this:
eval('$data[\''.implode("']['",explode('.',$path))."'] = 'my data';");
...but don't ever, ever tell anyone I told you to do this.
You can use eval function like so:
$data['level1']['level2']['level3'] = 'my data';
eval("\$index = \$data['level1']['level2']['level3'];");
echo $index;
Related
I'm creating a PHP class that manipulates csv files.
As part of the class I have a function that allows the data to be filtered showOnlyWhere. However I get this error Invalid argument supplied for foreach() on line 331 (the line with the foreach statement). I tried adding global $arr; but that didn't work. How would i fix it?
$this -> rows is a multi-dimensional array that contains all the csv data.
$arr is in the format:
$key=>$val array(
$key = Column Name
$val = value that column should contain
)
Below is the showOnlyWhere function
function showOnlyWhere($arr)
{
if($this->showOnlyWhere == true){
$rows = $this->filteredRows;
}
else{
$rows = $this->rows;
}
$filter = function ($item){
global $arr; // didn't work
foreach($arr as $chkCol => $chkVal){
if ($item[$arr[$chkCol]] != $chkVal ){
return false;
break(3);
}
}
return true;
};
$this->filteredRows = array_filter($rows,$filter);
$this->showOnlyWhere = true;
}
I think the error might have something to do with the Anonymous function - but I'm not really sure.
instead of using global $arr you can make $arr available to the anonymous function via use
$filter = function ($item) use ($arr) {
//global $arr; // didn't work
foreach($arr as $chkCol => $chkVal){
if ($item[$arr[$chkCol]] != $chkVal ){
return false;
}
}
return true;
};
Also, I noticed that you are assigning $rows = $this->filteredRows; before you populate $this->filteredRows. I'm not sure if that's intentional?
Format for your $arr is wrong.
this is wrong:
$key=>$val array(
$key = Column Name
$val = value that column should contain
)
You cannot supply class objects to foreach, it should be a valid array.
It should be like this:
$arr=array(
$key => 'Column Name',
$val = 'value that column should contain'
);
So first convert your object to a valid array.
Alright I'm working with a large multidimensional array which has more information in it than I need and I want to loop through it to filter the data which I'm interested in. Sadly this multidimensional array is produced dynamically and doesn't always contain the data I want, so I have to use logic like:
if(isset($ar['b']['ba']['baa'])){
echo '<h3>'.$ar['b']['ba']['baa'].'</h3>';
}
if(isset($ar['b']['ba']['baba'])){
echo '<h3>'.$ar['b']['ba']['baba'].'</h3>';
}
if(isset($ar['b']['ba']['babb'])){
echo '<h3>'.$ar['b']['ba']['babb'].'</h3>';
}
The above works great but its a bit messy-looking so I converted the above to:
$refAr=array();
$refAr[]='b->ba->baa';//3
$refAr[]='b->ba->bab->baba';//4
$refAr[]='b->ba->bab->babb';//5
The above looks a lot more nice and neat and is how I want to control the script in case I need to reference different keys in the future. The problem I am having is trying to use the above format to actually reference the array. I thought variable variables would work but apparently it fails. My second attempt using eval worked but I'm not very happy with my solution. This is where I need you guys to come in, is there a better way to do this? Here's my attempt below:
<?php
$ar=array(
'a'=>array('aa'=>1,'ab'=>2),
'b'=>array(
'ba'=>array('baa'=>3,'bab'=>array('baba'=>4,'babb'=>5),'bac'=>array('baca'=>6,'bacb'=>7)),
)
);
$refAr=array();
$refAr[]='b->ba->baa';//3
$refAr[]='b->ba->bab->baba';//4
$refAr[]='b->ba->bab->babb';//5
foreach($refAr as $ref)
{
$r=explode('->',$ref);
$r="\$ar['".implode("']['",$r)."']";
echo '<h1>'.$r.'</h1>';
echo '<h3>'.$$r.'</h3>';//undefined
eval('$t='.$r.';');
echo "<h3>$t</h3>";//works but uses eval, is there a better way?
}
You can try
$ar = array();
$ar['b']['ba']['baa'] = 3;
$ar['b']['ba']['bab']['baba'] = 4;
$ar['b']['ba']['bab']['babb'] = 5;
$refAr = array();
$refAr[] = 'b->ba->baa'; // 3
$refAr[] = 'b->ba->bab->baba'; // 4
$refAr[] = 'b->ba->bab->babb'; // 5
foreach ( $refAr as $ref ) {
$t = $ar;
foreach ( explode("->", $ref) as $v ) {
if (!isset($t[$v]))
break;
$t = $t[$v];
}
is_array($t) and $t = null;
echo "<h3>$t</h3>";
}
Output
345
I decided to answer my own question. This is what I wound up using:
<?php
//Sample PHP representation of dynamically-pulled JSON data from an untrusted source
$ar=array(
'a'=>array('aa'=>1,'ab'=>2),
'b'=>array(
'ba'=>array('baa'=>3,'bab'=>array('baba'=>4,'babb'=>5),'bac'=>array('baca'=>6,'bacb'=>7)),
)
);
//Reusable function
function resolveReference($ar,&$ref)
{
$t = $ar;
foreach ( explode('->',$ref) as $v )
{
if (!array_key_exists($v,$t)){$ref=null;return false;}
$t = $t[$v];
}
$ref=$t;
return true;
}
//The references I'm interested in but don't know if my dynamic data will contain these keys every time
$refAr=array();
$refAr[]='b->ba->baa';
$refAr[]='b->ba->bab->baba';
$refAr[]='b->ba->bab->babb';
$refAr[]='b->doesnt->exist';
foreach($refAr as $ref)
{
echo '<h1>'.$ref.'</h1>';
if(resolveReference($ar,$ref))
{
echo '<h3><span style="color:blue;">'.$ref.'</span></h3>';
}else{
echo '<h3><span style="color:red;">Alternative text for non-existent expected reference</span></h3>';
}
}
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How to get a variable name as a string in PHP?
Example:
Can something like this be achieved in PHP?
$Age = 43;
output_variable_name_and_value($Age);
/*
outputs:
"The requested variable name is Age and its current value is 43";
*/
//If possible, how would the line marked below with ? ? ? ? be?
function output__variable_name_and_value($input)
{
$var_name = get_name_somehow($input); // ? ? ? ?
echo "The requested variable name is {$var_name}
and its current value is {$input}";
}
This is not possible, easily. You have to use $GLOBALS;
function get_variable_name($var) {
foreach($GLOBALS as $k => $v) {
if ($v === $var) {
return $k;
}
}
return false;
}
The only downfall is, it may return a different variable name if they both have the same value.
Or this,
function varName( $v ) {
$trace = debug_backtrace();
$vLine = file( __FILE__ );
$fLine = $vLine[ $trace[0]['line'] - 1 ];
preg_match( "#\\$(\w+)#", $fLine, $match );
print_r( $match );
}
which I found here: How to get a variable name as a string in PHP?
You can use this function:
function var_name(&$iVar, &$aDefinedVars) {
foreach ($aDefinedVars as $k=>$v)
$aDefinedVars_0[$k] = $v;
$iVarSave = $iVar;
$iVar =!$iVar;
$aDiffKeys = array_keys (array_diff_assoc ($aDefinedVars_0, $aDefinedVars));
$iVar = $iVarSave;
return $aDiffKeys[0];
}
Call it like this:
var_name($Age, get_defined_vars());
Source: http://mach13.com/how-to-get-a-variable-name-as-a-string-in-php
Well..
You can figure out what called the output__variable_name_and_value function using debug_backtrace.
Then you know a filename and line number, so you could try to parse the sourcefile and figure out whats between output__variable_name_and_value( and ).
Probably a bad idea though!
Everybody knows that you can access a variable in PHP using this: ${'varName'}. But when you need to get/set a variable witch is part of an array, why doesn't it work ? Suppose we have this piece of code:
<?php
$myArray = array(...);
$myVarName = "myArray['my1']['my11']['my111']";
${$myVarName} = "new value";
?>
Shouldn't it work ?
I have tested it again and again - it is not working..
Is it there a way to do that?
I recommend you not to use dynamic variables like ${$var}.
What you want is modifying a multi-dimensional associative array according to a path of keys.
<?php
$myArray = array(...); // multi-dimensional array
$myVarPath = array('my1', 'my11', 'my111');
setValueFromPath($myArray, $myVarPath);
function getValueFromPath($arr, $path)
{
// todo: add checks on $path
$dest = $arr;
$finalKey = array_pop($path);
foreach ($path as $key) {
$dest = $dest[$key];
}
return $dest[$finalKey];
}
function setValueFromPath(&$arr, $path, $value)
{
// we need references as we will modify the first parameter
$dest = &$arr;
$finalKey = array_pop($path);
foreach ($path as $key) {
$dest = &$dest[$key];
}
$dest[$finalKey] = $value;
}
This is a procedural example to keep it simple. You may want to put your hierarchical array and this functions inside a class.
Shouldn't it work ?
No.
Everybody knows that you can access a variable in PHP using this: ${'varName'}.
Yes. Yet everybody knows that's lame.
How to refer dynamically to a php array variable(s)?
having array of ('my1','my11','my111') you can refer to any particular array member using merely a loop.
You could do something like this, but it would be a really bad idea. Sorry Col. ;)
<?php
$mA = array();
$mVN = "mA['m1']['m2']['m3']";
eval('$'. $mVN . ' = "new value";');
print_r($mA);
?>
I want to pass one argument to a function, rather than multiple arguments, that tend to grow unexpectedly. So I figure an array will get the job done. Here's what I've drafted so far...
<?php
function fun_stuff($var){
// I want to parse the array in the function, and use
}
$my = array();
$my['recordID'] = 5;
$my['name'] = 'John Smith';
$my['email'] = 'john#someemail.com';
echo fun_stuff($my);
?>
I haven't quite grasped the concept of parsing an array. And this is a good way for me to learn. I generally pass the same variables, but on occasion a record does not have an email address, so I do need to make a condition for missing keys.
Am I doing this right so far? Can I pass an array as an argument to a function?
And if so, how do I parse and search for existing keys?
Hopefully this isn't too far off topic...but you sounded like you were just trying to avoid multiple parameters when some can be NULL. So, I would recommend that you use an object instead of an array for clarity...that way, there is no confusion as to what properties should exist. If you're using PHP 5, you can also strongly type the parameter so nothing else can get in. So:
class Record {
public $Id;
public $Name;
public $Email
}
function fun_stuff( Record $record ) {
// you will now have better intellisense if you use an IDE
// and other develoers will be able to see intended parameters
// clearly, while an array would require them to know what's
// intended to be there.
if( !empty($record->Email) ) {
// do whatever.
}
}
Yes you are on the right track. The approach I take is put required paramters as the first parameters and all optional parameters in the last argument which is an array.
For example:
function fun_stuff($required1, $required2, $var = array()) {
// parse optional arguments
$recordId = (key_exists('recordID', $var) ? $var['recordId'] : 'default value');
$name = (key_exists('name', $var) ? $var['name'] : 'default value');
$email = (key_exists('email', $var) ? $var['email'] : 'default value');
}
Then you can call your function like so:
fun_stuff('val 1', 'val 2', array(
'recordId' => 1,
'name' => 'John',
'email' => 'john#stackoverflow.com'
));
This is a bad design practice, but that's not the question here. You can "parse" array's like so...
if( array_key_exists( 'email', $var ))
{
// use email field
}
If you need to, you can loop through all elements like so...
foreach( $var as $key => $value )
{
echo '$var[\''.$key.'\'] = '.$value;
}
I'm not recommend you to use array for this.
You can define optional arguments with default values:
//$name and $email are optional here
function fun($record_id, $name='', $email='')
{
if (empty($name)) print '$name is empty';
}
//Usage:
fun(5, 'Robert');
fun(5);
fun(5, 'Robert', 'robert#gmail');
fun(3,'','robert#gmail');
If you will use array, IDE will not be able to show autocomplete suggestions, it means more typos, and you have to remember all keys of this array forever or look at code of the function each time.
I'm not really sure what you want to achieve, but I suspect something like this:
$aPersons = array();
$aPersons[] = array('name' => 'name1', 'age' => 1);
$aPersons[] = array('name' => 'name2', 'age' => 2);
array_map('parsePerson', $aPersons);
function parsePerson($aPerson) {
echo $aPerson['name'];
echo $aPerson['age'];
}
The problem with your current array is that it only has one dimension.
You can simple do echo $my['name'];. There are easier ways to parse arrays though.
foreach($aPersons as $aPerson) {
echo $aPerson['name'];
echo $aPerson['age'];
}
$iLength = sizeof($aPersons);
for($i = 0; $i <= $iLength; $i++) {
echo $aPersons[$i]['name'];
echo $aPersons[$i]['age'];
}
To parse and view, there is the signficant print_r function which gives out the array details.
When calling a function you need the return syntax at the end that will parse out anything you call in the return.
You obviously can pass array to the function. Inside it read the variable as you were assigning values before it. If you assign:
$my['key'] = 'value';
In you function use:
echo $var['key'];
Why you don't use a foreach to walk in array?
function fun_stuff($var){
foreach($var as $key => $item){
echo '[', $key, "] => ", $item, "\n";
}
}
$my = array();
$my['recordID'] = 5;
$my['name'] = 'John Smith';
$my['email'] = 'john#someemail.com';
fun_stuff($my);
Yes, this is correct (though your question is a bit broad). You're already referencing the array values via indexes when you set up the $my variable. You can do the same thing within your function (with the $var variable).
I recommend taking a look at all of PHP's built-in array functions: http://php.net/manual/en/ref.array.php
Try this:
function fun_stuff($var){
// I want to parse the array in the function, and use
$fun_string = "";
if( is_array( $var ) {
if( array_key_exists( "name", $var ) )
$fun_string .= "For " . $var["name"];
else $fun_string .= "A nameless one ";
if( array_key_exists( "email", $var ) )
$fun_string .= " (email: " . $var["email"] . ")";
else $fun_string .= " without a known e-mail address";
if( array_key_exists( "recordID", $var ) )
$fun_string .= " has record ID of " . $var["recordID"];
else $fun_string .= " has no record ID set";
$fun_string .= "\n";
}
return $fun_string;
}
Yes You can! Just pass the array and inside the function just use a foreach loop to parse it!
function myFunction($array)
{
foreach($array as $value)
{
echo $value;
}
}
or If you want to have full control over the pair key/value:
function myFunction($array)
{
foreach($array as $key=>$value)
{
echo "key:".$array[$key]."value:".$values;
}
}