Extension:External Data/Common problems


 * If the call to #get_web_data or #for_external_table isn't returning any data, and the page being accessed is large, it could be because the call to retrieve is getting timed out. You should set the flag in your LocalSettings.php file (which represents a number of seconds) to some number greater than 25, its default value. You could call, for instance:




 * If the data being accessed has changed, but the wiki page accessing it still shows the old data, it is because that page is being cached by MediaWiki. There are several solutions to this: if you are an administrator, you can hit the "refresh" tab above the page, which will purge the cache. You can also easily disable caching for the entire wiki; see here for how. Finally, if you wait long enough (typically no more than 24 hours), the page will get refreshed on its own and display the new data.


 * If you host a private wiki locally but use a dynamic IP service to access it, your wiki will connect to itself through your public IP and not through localhost or 127.0.0.1 (or an IPv6 equivalent). In such a case, your wiki is not allowed to query itself so the examples given here will work when data are hosted on a different server but not if they are hosted on your wiki. A workaround is to use the extension Extension:NetworkAuth which allows you to automatically authenticate your router/box/modem to access your wiki. Note: the security of this approach is not guaranteed.


 * If the extension is not correctly handling non-ASCII characters, the problem might be that your PHP instance lacks the mbstring extension - make sure that it is installed.


 * To query data from another wiki that uses Semantic MediaWiki, it is recommended to use the Special:Ask page, rather than one of SMW's API actions, to construct the URL that will be passed in to #get_web_data, since the API will not output data in a syntax that External Data can use. To construct the URL, go to Special:Ask, create the desired query, then copy the URL from the "Download queried results in CSV format" link.
 * Adapting queries of SMW data for use inside templates by adding parameters is problematic. For that to work, special characters contained in the parameter must be escaped. The general encoding method is hex ASCII encoding. However, the character placed by SMW immediately before the ASCII hex code to is sometimes a hypen minus (-) and sometimes a percent sign (%). Furthermore, SMW sometimes encodes colons and sometimes not. It is currently unclear what causes SMW to apply either one or the other encoding method. Unclear to User:Kaleido; Who can provide a clarification? Absent that knowledge, the creation of appropriate encoding scripts might not be possible.