I am trying to catch an error with php when I connect to DB
I have something like
try{
//connect to DB
}catch(exception $e){
echo $e
}
//other php codes...
//My html elements...
<div>....
My problem is that I want to skip //other phpo codes if we have error connecting to DB and straight to show my html elements. Is that possible to do it? Thanks a lot.
Just out that code in your try/catch. Once the exception is thrown execution is handed off to the catch portion of the control structure and that portion of code is never reached:
try{
//connect to DB
// If an exception is throw above we never get here
//other php codes...
}catch(exception $e){
echo $e
}
//My html elements...
<div>....
If you don't want to move the // other php code
And you don't want/can't edit the try/catch block, surely the try/catch returns some variable you can test, even if only that $e.
try {
// something like $connected_db should be available
}
catch (exception $e)
{
}
if (!empty($connected_db) AND empty($e)) // one or the other depending on the code above
{
// other php code
}
// my html elements
Related
I have a PHP psql query. I am doing try catch to prevent Duplicates. When I ran the script I can see it's inserting something into my DB. But when I check my DB it's empty.
foreach($data as $n){
$query = $psql->pdo_prepared("INSERT INTO students(id,email,address,phone)VALUES".myFunction($array);
}
and I have a PHP class to handle the exception:
public function pdo_prepared($query,array){
try{
// some logic
}
catch(EXCEPTION $e){
//empty
}
}
The reason why I am doing try catch is to catch duplicates and ignore it. If I throw an exception in my catch block my insert statement won't execute because my current data contains duplicates.
I have require statements for my header and footer:
<?php
require "assets/php/header.php";
// Script goes here.
require "assets/php/footer.php";
?>
If I have a script in between the two statements, how can I have a die() statement in the script to end the current script, but still show the footer? If there is no way of doing this, is there any alternatives? I personally think that the require statements are obsolete, and I would love to know of some alternatives, or just a better way of setting it up. Thanks in advance.
You should use exception.
Try something like this :
<?php
try {
require "assets/php/header.php";
// Script goes here.
// replace "die();" with :
throw new Exception("I want to die");
// folowing code executed if no exception is thrown
require "assets/php/footer.php";
// end of "normal" case
} catch (Exception $e) {
// an exception makes footer and then dies
require "assets/php/footer.php";
die();
}
?>
you can also use this catch if you use Exception that mustn't trigger footer :
} catch (Exception $e) {
if($e->getMessage() == "I want to die") {
// an exception asks to make footer and then dies
require "assets/php/footer.php";
die();
} else {
throw $e;
}
}
Or if you want to make it clean, make a new exception class (for instance DieWithFooterException) and use it like this :
<?php
try {
require "assets/php/header.php";
// Script goes here.
// replace "die();" with :
throw new DieWithFooterException();
// folowing code executed if no exception is thrown
require "assets/php/footer.php";
// end of "normal" case
} catch (DieWithFooterException $dwfe) {
// an exception asks to make footer and then dies
require "assets/php/footer.php";
die();
} catch (Exception $e) {
// stuff to do with other excpetions
}
?>
This said, the last solution is the nicer way to do it :)
Consider these two examples
<?php
function throw_exception() {
// Arbitrary code here
throw new Exception('Hello, Joe!');
}
function some_code() {
// Arbitrary code here
}
try {
throw_exception();
} catch (Exception $e) {
echo $e->getMessage();
}
some_code();
// More arbitrary code
?>
and
<?php
function throw_exception() {
// Arbitrary code here
throw new Exception('Hello, Joe!');
}
function some_code() {
// Arbitrary code here
}
try {
throw_exception();
} catch (Exception $e) {
echo $e->getMessage();
} finally {
some_code();
}
// More arbitrary code
?>
What's the difference? Is there a situation where the first example wouldn't execute some_code(), but the second would? Am I missing the point entirely?
If you catch Exception (any exception) the two code samples are equivalent. But if you only handle some specific exception type in your class block and another kind of exception occurs, then some_code(); will only be executed if you have a finally block.
try {
throw_exception();
} catch (ExceptionTypeA $e) {
echo $e->getMessage();
}
some_code(); // Will not execute if throw_exception throws an ExceptionTypeB
but:
try {
throw_exception();
} catch (ExceptionTypeA $e) {
echo $e->getMessage();
} finally {
some_code(); // Will be execute even if throw_exception throws an ExceptionTypeB
}
fianlly block is used when you want a piece of code to execute regardless of whether an exception occurred or not...
Check out Example 2 on this page :
PHP manual
Finally will trigger even if no exception were caught.
Try this code to see why:
<?php
class Exep1 extends Exception {}
class Exep2 extends Exception {}
try {
echo 'try ';
throw new Exep1();
} catch ( Exep2 $e)
{
echo ' catch ';
} finally {
echo ' finally ';
}
echo 'aftermath';
?>
the output will be
try finally
Fatal error: Uncaught exception 'Exep1' in /tmp/execpad-70360fffa35e/source-70360fffa35e:7
Stack trace:
#0 {main}
thrown in /tmp/execpad-70360fffa35e/source-70360fffa35e on line 7
here is fiddle for you. https://eval.in/933947
From the PHP manual:
In PHP 5.5 and later, a finally block may also be specified after or instead of catch blocks. Code within the finally block will always be executed after the try and catch blocks, regardless of whether an exception has been thrown, and before normal execution resumes.
See this example in the manual, to see how it works.
http://www.youtube.com/watch?v=EWj60p8esD0
Watch from: 12:30 onwards
Watch this video.
The language is JAVA though.
But i think it illustrates Exceptions and the use of finally keyword very well.
In the controllers class files, most of the method functions include try/catch block something like this:
try
{
$stmt = $this->prepare($sql);
$stmt->execute($params);
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);
//foreach() or so on...
}
catch (Exception $e)
{
//bunch of code...
//save error into database, etc.
//error into json and pass to view file
}
There are a lot of code in the catch block, is there a way to reduce it. Is possible to add "throw exception" in the catch block?
Yes, it is. Try it by yourself. You can always throw a new Exception in a catch block or rethrow the same exception.
try
{
// ...
}
catch (Exception $e)
{
// do whatever you want
throw new Your_Exception($e->getMessage());
// or
throw $e;
}
I don't know what "bunch of code" is. I'm not sure I believe you. If you have that much going on in a catch block you're doing something wrong.
I'd put this kind of code into an aspect if you have AOP available to you.
"Error into database" might throw its own exception. What happens to that?
The only step that I see here that's necessary is routing to the error view.
What does rethrowing the exception do? It's just passing the buck somewhere else. If all these steps don't need to be done, and all you're doing to rethrowing, then don't catch it at all. Let the exception bubble up to where it's truly handled.
You shouldn't be catching Exception. That's much too general. Catch each specific type of Exception with multiple catch statements on your try block:
try {
} catch(PDOException $err) {
} catch(DomainException $err) {
}
I'd like to use an exception for error handling in a part of my code but if the code should fail, I would like the script to continue. I want to log the error though. Can someone please help me figure this out?
try{
if($id == 4)
{
echo'test';
}
}
catch(Exception $e){
echo $e->getMessage();
}
echo'Hello, you should see me...'; <------ I never see this.. No errors, just a trace.
You have to catch the exception :
// some code
try {
// some code, that might throw an exception
// Note that, when the exception is thrown, the code that's after what
// threw it, until the end of this "try" block, will not be executed
} catch (Exception $e) {
// deal with the exception
// code that will be executed only when an exception is thrown
echo $e->getMessage(); // for instance
}
// some code, that will always be executed
And here are a couple of things you should read :
Exceptions in the PHP manual
Exceptional PHP: Introduction to Exceptions
In the code that is calling the code that may throw an Exception do
try {
// code that may break/throw an exception
echo 'Foo';
throw new Exception('Nothing in this try block beyond this line');
echo 'I am never executed';
throw new CustomException('Neither am I');
} catch(CustomException $e) {
// continue here when any CustomException in try block occurs
echo $e->getMessage();
} catch(Exception $e) {
// continue here when any other Exception in try block occurs
echo $e->getMessage();
}
// script continues here
echo 'done';
Output will be (adding line breaks for readability):
'Foo' // echoed in try block
'Nothing in this try block beyond this line' // echoed in Exception catch block
'done' // echoed after try/catch block
Try/Catch Blocks may also be nested. See Example 2 in the PHP Manual page linked above:
try{
try {
throw new Exception('Foo');
echo 'not getting here';
} catch (Exception $e) {
echo $e->getMessage();
}
echo 'bar';
} catch (Exception $e) {
echo $e->getMessage();
}
echo 'done';
'Foo' // echoed in inner catch block
'bar' // echoed after inner try/catch block
'done' // echoed after outer try/catch block
Further reading at DevZone:
http://devzone.zend.com/node/view/id/666
http://devzone.zend.com/article/679-Exceptional-Code---PART-2
http://devzone.zend.com/node/view/id/652
http://devzone.zend.com/article/653-PHP-101-PART-12-BUGGING-OUT---PART-2