Thursday, 13 November 2014

Cordova Plugin is not Available when Application Starts

If you use a plugin and execute its method when your application starts and have this error:
TypeError: Cannot read property '[your_plugin_name]' of undefined at Object.[plugin_method]
then it is likely that the plugin has not been initialised fully when the method is called.

To solve this issue, wait until deviceready event is fired before calling the plugin's method.

With AngularJS, I like to wait until deviceready event is fired before loading the whole application. To do this, make sure that ng-app declaration is removed from the HTML, then bootstrap the app when deviceready event has fired. document.addEventListener is used to determine whether the event has been fired.
document.addEventListener("deviceready", function() {
    angular.bootstrap(document, ["myApp"]);
}, false);
If you want to apply this to a particular element instead of the whole HTML document (or body), you could use:
var theElement = document.findByID(...) // or document.querySelector(...);
angular.bootstrap(theElement, ["myApp"]);

Then you can call the rest scripts:
var myApp= angular.module('myApp', [. . .]);

  . . .

Friday, 7 November 2014

Concatenating Results in SQL Query

Below is an example to concatenate results in an SQL query:
SELECT S.FirstName, S.LastName,
    ( SELECT ',' + S1.FirstName + ' ' + S1.LastName FROM Student S1 WHERE S1.FirstName = S.FirstName FOR XML PATH('') ), 
  ) AS AnyStudentsWithSimilarNames
FROM Student S

In the example, we use FOR XML PATH('') to concatenate the result from multiple rows into a single value.

We also use STUFF() function to simply remove the first occurrence of ',' character. The syntax is STUFF( expression, starting_character_position, length, replace_with_expression ).

If we have '<', '>' or '&' characters in our projection and want to avoid those getting encoded, we can replace the codes inside STUFF() function to:
Here we add TYPE to have the query with FOR XML PATH() returns XML data type then we use VALUE() function to get the value. Both are used as a work around to avoid the characters getting encoded.