In my local/development environment, the MySQLi query is performing OK. However, when I upload it on my web host environment, I get this error:
Fatal error: Call to a member function bind_param() on a non-object in...
Here is the code:
global $mysqli;
$stmt = $mysqli->prepare("SELECT id, description FROM tbl_page_answer_category WHERE cur_own_id = ?");
$stmt->bind_param('i', $cur_id);
$stmt->execute();
$stmt->bind_result($uid, $desc);
To check my query, I tried to execute the query via control panel phpMyAdmin and the result is OK.
TL;DR
Always have mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); in your mysqli connection code and always check the PHP errors.
Always replace every PHP variable in the SQL query with a question mark, and execute the query using prepared statement. It will help to avoid syntax errors of all sorts.
Explanation
Sometimes your MySQLi code produces an error like mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given..., Call to a member function bind_param()... or similar. Or even without any error, but the query doesn't work all the same. It means that your query failed to execute.
Every time a query fails, MySQL has an error message that explains the reason. In the older PHP versions such errors weren't transferred to PHP, and all you'd get is a cryptic error message mentioned above. Hence it is very important to configure PHP and MySQLi to report MySQL errors to you. And once you get the error message, fixing it will be a piece of cake.
How to get the error message in MySQLi
First of all, always have this line before MySQLi connect in all your environments:
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
After that, all MySQL errors will be transferred into PHP exceptions. An uncaught exception, in turn, makes a PHP fatal error. Thus, in case of a MySQL error, you'll get a conventional PHP error. That will instantly make you aware of the error cause. And the stack trace will lead you to the exact spot where the error occurred.
How to get the error message from PHP
Here is a gist of my article on PHP error reporting:
Reporting errors on a development and live servers must be different. On the development server it is convenient to have errors shown on-screen, but on a live server error messages must be logged instead, so you could find them in the error log later.
Therefore, you must set corresponding configuration options to the following values:
On a development server
error_reporting should be set to E_ALL value;
log_errors should be set to 1 (it is convenient to have logs on a development PC too)
display_errors should be set to 1
On a production server
error_reporting should be set to E_ALL value;
log_errors should be set to 1
display_errors should be set to 0
After that, when MySQL query fails, you will get a PHP error that explains the reason. On a live server, in order to get the error message, you'll have to check the error log.
In case of AJAX call, on a dev server open DevTools (F12), then Network tab. Then initiate the request which result you want to see, and it will appear in the Network tab. Click on it and then the Response tab. There you will see the exact output. On a live server check the error log.
How to actually use it
Just remove any code that checks for the error manually, all those or die(), if ($result), try..catch and such. Simply write your database interaction code right away:
$stmt = $this->con->prepare("INSERT INTO table(name, quantity) VALUES (?,?)");
$stmt->bind_param("si", $name, $quantity);
$stmt->execute();
Again, without any conditions around. If an error occurs, it will be treated like any other error in your code. For example, on a development PC it will just appear on-screen, while on a live site it will be logged for the programmer, whereas for the user's convenience you could use an error handler (but that's a different story which is off topic for MySQLi, but you may read about it in the article linked above).
What to do with the error message you get
First of all you have to locate the problem query. The error message contains the file name and the line number of the exact spot where the error occurred. For the simple code that's enough, but if your code is using functions or classes you may need to follow the stack trace to locate the problem query.
After getting the error message, you have to read and comprehend it. It sounds too obvious if not condescending, but learners often overlook the fact that the error message is not just an alarm signal, but it actually contains a detailed explanation of the problem. And all you need is to read the error message and fix the issue.
Say, if it says that a particular table doesn't exist, you have to check spelling, typos, and letter case. Also you have to make sure that your PHP script connects to a correct database
Or, if it says there is an error in the SQL syntax, then you have to examine your SQL. And the problem spot is right before the query part cited in the error message.
If you don't understand the error message, try to google it. And when browsing the results, stick to answers that explain the error rather than bluntly give the solution. A solution may not work in your particular case, but the explanation will help you to understand the problem and make you able to fix the issue by yourself.
You have to also trust the error message. If it says that number of tokens doesn't match the number of bound variables then it is so. The same goes for the absent tables or columns. Given the choice, whether it's your own mistake or the error message is wrong, always stick to the former. Again it sounds condescending, but hundreds of questions on this very site prove this advise extremely useful.
A list of things you should never ever do in regard of error reporting
Never use an error suppression operator (#)! It makes a programmer unable read the error message and therefore unable to fix the error
Do not use die() or echo or any other function to print the error message on the screen unconditionally. PHP can report errors by itself and do it the right way depends on the environment - so just leave it for PHP.
Do not add a condition to test the query result manually (like if($result)). With error exceptions enabled such condition will just be useless.
Do not use the try..catch operator for echoing the error message. This operator should be used to perform some error handling, like a transaction rollback. But never use it just to report errors - as we learned above, PHP can already do it, the right way.
P.S.
Sometimes there is no error, but no results either. Then it means, there is no data in the database to match your criteria. In this case you have to admit this fact, even if you can swear the data and the criteria are all right. They are not. You have to check them again.
I've got an article that can help in this matter, How to debug database interactions. Although it is written for PDO, the principle is the same. Just follow those instructions step by step and either have your problem solved or have an answerable question for Stack Overflow.
Transformation Parse Warning [<<P M Parse Warning>> <<Invalid constant sun-expression>> <<Expression Error>> [TO_DATE]:invalid string for converting to Date
… t:TO_DATE(s:s:”,s:s:’YYYYMMDD’)
……….
AND SATIS_TARIHI = >>>> TO_DATE($$RUN_DATE,’YYYYMMDD’)<<<<];
How can I solve this?
This is the first time I encounter this error. Normally, this is a daily routine for our job. The parameter is successfully added to the mapping and all the other things seem okay. I’d appreciate your help.
I tried to start the workflow and got this error.
You need to define a $$RUN_DATE in mapping. Currently its not defined in mapping or its null in parameter file.
You need to set a default value in mapping like 20221221 for today.
Or else you can set it up in a parameter file like this
[folder.workflow_name]
[folder.session_name]
$$RUN_DATE=20221221
Considering this is your daily routine and up till now it has been working fine, I assume this is not a new development and no recent changes have been made. Apparantly PowerCenter got an invalid value for the parameter.
Check you parameter file and how it gets generated.
Was the process of generating paramfile executed without issues?
Was there enough storage space?
Can you verify the paramfile contents?
Can you regenerate it?
Can you modify it and provide some value manually?
Feel free to get back with some updates for more help if your problem won't get resolved by checking the items on the list above.
I've been asked to look at C# code that's returning the following error:
Unable to cast object of type
'iTextSharp.text.html.simpleparser.IncCell' to type 'iTextSharp.text.Rectangle'.
at iTextSharp.text.pdf.PdfDocument.Add(IElement element)
at iTextSharp.text.Document.Add(IElement element)
It looks like they're using iTextSharp v5.0.2 and have not yet moved from HtmlWorker to XmlWorker.
Questions:
What is IncCell? I see it in the source docs but can't find any info about what it is - I'm assuming it's just for internal use.
Is this related to a cell in a table? A need for a Div or Paragraph within a cell?
What can they do to diagnose issues like this down to the HTML source that caused the error? I suspect this is an issue with not conforming to XHTML, but I can't verify that without knowing exactly what IElement that code was working on when it choked. It could be due to bad styling too, I have no idea at this time. Is there any kind of detail logging that will tell us what element is being processed at any given time? Should I just get them to load source and trace through it?
Is it probable that this will be fixed with an update to the latest version (currently 5.5.9), and a re-fit of XmlWorker?
Other recommendations?
Thanks!
In Exist 2.2, When I try to access any .xpl files with REST GET, I get the following error:
/db/beheer/pipe.xpl err:XPST0003
error found while loading module xproc: Error while loading module
http://xproc.net/xproc: unexpected token: ! (while expecting closing
tag for element constructor: null) [at line 1, column 2]
It seems to me that Exist is processing the *.xpl as if it was something it could execute (like a stored xquery) but then it cannot do so and returns an error.
Is there an easy way to let it return just the XML (the XProc as is instead of error message)?
Indeed, eXist consults its list of Internet Media Types when you do a HTTP GET using the REST Server and if it thinks that it is an XProc it will attempt to execute it as such.
You can change what eXist thinks is an XProc by editing $EXIST_HOME/mime-type.xml and then restarting eXist. You most likely want to move the .xpl extension from the mimetype application/xml+xproc to application/xml.
When creating my own macro, and trying to add it so that anyone can use it, I get the following error:
Error number 4001 in 4: Error while parsing velocity page /templates/docdoesnotexist.vm
Wrapped Exception: Cannot start the Velocity engine
I do not change that file, but I do change xwiki/templates/macros.txt and /macros.vm by adding recentChanges=velocity:recentChanges: and #macro(recentChanges) respectively (yes, I do add working content after #macro(recentChanges))
That looks like a syntax error in macros.vm. You should revert to the original macros.vm and first try to write your custom macro in a wiki page. Once it works, you can move it to macros.vm and restart the server.
macros.txt shouldn't be edited, it's a legacy file used by the older WYSIWYG editor.