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https://github.com/silverstripe/silverstripe-framework
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106 lines
3.8 KiB
Markdown
106 lines
3.8 KiB
Markdown
# Error Handling
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SilverStripe has its own error trapping and handling support.
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## Error Levels
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SilverStripe recognises two basic levels of error:
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* **WARNING:** Something strange has happened; the system has attempted to continue as best it can, but the developers
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need to look at this. This category also include areas where a newer version of SilverStripe requires changes to the
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site's customised code.
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* **FATAL ERROR:** There is no way that the system can attempt to continue with the particular operation; it would be
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dangerous to report success to the user.
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You should use [user_error](http://www.php.net/user_error) to throw errors where appropriate. The more information we
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have about what's not right in the system, the better we can make the application.
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* **E_USER_WARNING:** Err on the side of over-reporting warnings. The more warnings we have, the less chance there is
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of a developer leaving a bug. Throwing warnings provides a means of ensuring that developers know whow
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* Deprecated functions / usage patterns
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* Strange data formats
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* Things that will prevent an internal function from continuing. Throw a warning and return null.
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* **E_USER_ERROR:** Throwing one of these errors is going to take down the production site. So you should only throw
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E_USER_ERROR if it's going to be **dangerous** or **impossible** to continue with the request.
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Note that currently, the SilverStripe core doesn't follow these standards perfectly.
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* Right now, **every** failed SQL statement throws a fatal error. Many 'select' queries could probably be reduced to
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warnings.
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* A lot of assertion checking in the system that throws errors when it should throw warnings.
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## Friendly Website Errors
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An HTTP 500 error will be sent when there has been a fatal error on either a test or production site. You can make this
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friendlier - much like the 404 page, the error content can be edited within the CMS.
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* Create a page of type `[api:ErrorPage]`
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* Set the error code to 500
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* Publish the page.
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**HOW IT WORKS: **The publication script for ErrorPage will write the full HTML content, including the template styling,
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to assets/error-500.html. The fatal error handler looks for the presence of this file, and if it exists, dumps the
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content. This means that database access isn't required to provide a 500 error page.
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## Filesystem Logs
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### From SilverStripe
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*Requires SilverStripe 2.3*
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You can indicate a log file relative to the site root. The named file will have a terse log sent to it, and the full log
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(an encoded file containing backtraces and things) will go to a file of a similar name, but with the suffix ".full"
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added.
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<mysite>/_config.php:
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:::php
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// log errors and warnings
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SS_Log::add_writer(new SS_LogFileWriter('/my/logfile/path'), SS_Log::WARN, '<=');
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// or just errors
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SS_Log::add_writer(new SS_LogFileWriter('/my/logfile/path'), SS_Log::ERR);
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#### Deprecated method (SS 2.3 ?)
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<mysite>/_config.php:
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:::php
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Debug::log_errors_to("/my/logfile/path");
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### From PHP
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In addition to SilverStripe-integrated logging, it is adviseable to fall back to PHPs native logging functionality. A
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script might terminate before it reaches the SilverStripe errorhandling, for example in the case of a fatal error.
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<mysite>/_config.php:
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:::php
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ini_set("log_errors", "On");
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ini_set("error_log", "/my/logfile/path");
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## Email Logs
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You can send both fatal errors and warnings in your code to a specified email-address.
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<mysite>/_config.php:
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:::php
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// log errors and warnings
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SS_Log::add_writer(new SS_LogEmailWriter('admin@domain.com'), SS_Log::WARN, '<=');
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// or just errors
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SS_Log::add_writer(new SS_LogEmailWriter('admin@domain.com'), SS_Log::ERR);
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### Deprecated method (SS 2.3 ?)
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:::php
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Debug::send_errors_to("developer@example.org");
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Debug::send_warnings_to("developer@example.org"); // Optional, implied by send_errors_to()
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