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.
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1: I want to use check box but facing this error again and again.. I'm new in flutter what do I do now. https://i.stack.imgur.com/m9PdK.jpg
It seems that to believe the error message that is showing you have mutliple causes:
First the "error getter 'sortFilter' isn't defined means that you either didn't pass the argument or that simply the sortFilter isn't defined in your widget meaning that when you do widget.sortFilter, here sortFilter will be undefined.
Secondly, it appear that for the last error message selectedValue is just not initialized, you certainly put before, the keyword late to that variable and didn't put a value afterward. So try by default giving him true or false and at least you should have this solved.
Anyways, if those solution doesn't not work, please give a better overview or your code especially the widget CarInfoScreen.
I want to use my custom error messages in my citrus test results.
Example:
Original Error Message: java.io.FileNotFoundException: D:\expectedOutput\Smaple.xml (The system cannot find the file specified).
Custom Message: Hey The File was not found in your directory Please check. (Need to print like this in my test results failure message).
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You can not change this message in particular as this is coming from the thrown Java exception. You could implement your own TestReporter and/or TestListener though to translate the error into something matching your needs.
Something like: https://citrusframework.org/samples/reporting/
I want to verify the text present in placeholder. I have located the element and i am using Assert text command. I've entered the same string in value. On executing it is showing actual value did not match
Use assertAttribute or verifyAttribute command.
Example:
verifyAttribute | css=#search#placeholder | Sample String
Notes:
In the Target column of Selenium IDE, you need to provide the proper path of the element followed by an # sign
and then the name of the attribute. (placeholder in your case)
Using
verifyAttibute will still continue running the test case once an
error is detected while using assertAttribute doesn't.
You need to understand that assertText function can only check static text on your webpage.
You must be getting an error message.
This is perfectly normal.
What can help in this situation is using the assertAttribute or verifyAttribute functions.
Both these functions perform the same task; the former stops the test after receiving an error message in the text box while verifyValue just records the error in the log and runs the next commands.
While giving the target, either specify the XPath or refer by using the name=name#placeholder format.
You can find the name value by inspecting the box with a firefox addon called Firepath which runs with another firefox tool called Firebug. Install them if you don't already have.
Hope this helps!
Xpath contains() is the best way.
driver.find_element_by_xpath('//input[contains(#placeholder,"email")]')
Format : '//tag[contains(#attribute,"value")]'
I have a problem with Net::Appliance::Session. I created a session, executed my command. After execution it prompts me some question (yes/no). I want to answer it but didn't find a way how to do it. Below you can see my trials:
$session->cmd($command);
$session->waitfor(Match=>'/.*yes*/');
$session->print("no");
$session->waitfor(Match=>'');
$session->print("y");
I don't know where is the problem. Accoding to CPAN documentations Net::Telnet have the method waitfor. But Session documentation tells that we can use waitfor(). Another thing said there is that the method "cmd" have a member Match which includes all the features of waitfor(). So I changed my code like below:
$session->cmd($command, Match=>'/.*yes*/');
$session->print("no");
Executing this reports below error:
Odd number of elements in hash assignment at
/usr/lib/perl5/vendor_perl/5.8.8/Net/Appliance/Session.pm line 245.
Is there any idea how can I do that? And why am I getting this error message?
Thanks in advance..
From the Net::Appliance::Session page at meta::cpan
To handle more complicated interactions, for example commands which prompt for confirmation or optional parameters, you should use a Macro. These are set up in the phrasebook and issued via the $s->macro($name) method call. See the Phrasebook and Cookbook manual pages for further details.
So you set up a macro (scripted call and response) in a phrasebook, and then tell your session to use that macro.