Skip to main content

5 Cool Things you can do with HTML5 (p3)

By
Location, location, location, it's all about location...


Probably one of the most frequently used HTML5 features is geoLocation. Why? Because it is very easy to use and cool too!
You can check the corresponding example page on http://apex.oracle.com/pls/apex/f?p=22115:GEOLOCATION.
So how does that work?
In fact it is just a few lines of code. First include the Google Javascript API (<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>).
The next step (on Page Load) is to actually get the current position of the browser device by
if (navigator.geolocation) {
  navigator.geolocation.getCurrentPosition(showLocation, handleError);
} else {
  error('GeoLocation is not supported in this browser');
}
Where  showLocation specifies the callback method that retrieves the location information. This method is called asynchronously with an object corresponding to the Position object which stores the returned location information. So you can use this function to actually draw the map and place the marker. And ErrorHandler is an optional parameter that specifies the callback method that is invoked when an error occurs in processing the asynchronous call. This method is called with the PositionError object that stores the returned error information. So when somethings goes wrong you can show an alert with your own message.
Depending on the security settings of the browser, your user might see a message like "apex.oracle.com wants to track your physical location". The user has to accept or deny access to this information. In the privacy settings of your browser you can see what sites have access to your location.

And for actually determining your position, Google uses either your IP-address - so that might be quite inadequate when you use proxies - or the GPS in your (mobile) device. For the latter type of device you can also use navigator.geolocation.watchPosition(showLocation, handleError);. Then that function will be called every time the Geo of your device changes. So you can draw a map of where the user of your app has been during the period the app is active (like Runkeeper does).

You can see the full W3C API description here.
Labels:

Comments

Post a Comment

Popular posts from this blog

Filtering in the APEX Interactive Grid

By
Remember Oracle Forms? One of the nice features of Forms was the use of GLOBAL items. More or less comparable to Application Items in APEX. These GLOBALS where often used to pre-query data. For example you queried Employee 200 in Form A, then opened Form B and on opening that Form the Employee field is filled with that (GLOBAL) value of 200 and the query was executed. So without additional keys strokes or entering data, when switching to another Form a user would immediately see the data in the same context. And they loved that. In APEX you can create a similar experience using Application Items (or an Item on the Global Page) for Classic Reports (by setting a Default Value to a Search Item) and Interactive Reports (using the  APEX_IR.ADD_FILTER  procedure). But what about the Interactive Grid? There is no APEX_IG package ... so the first thing we have to figure out is how can we set a filter programmatically? Start with creating an Interactive Grid based upon the good old Employ
1 comment
Read more

apex_application.g_f0x array processing in Oracle 12

By
If you created your own "updatable reports" or your custom version of tabular forms in Oracle Application Express, you'll end up with a query that looks similar to this one: then you disable the " Escape special characters " property and the result is an updatable multirecord form. That was easy, right? But now we need to process the changes in the Ename column when the form is submitted, but only if the checkbox is checked. All the columns are submitted as separated arrays, named apex_application.g_f0x - where the "x" is the value of the "p_idx" parameter you specified in the apex_item calls. So we have apex_application.g_f01, g_f02 and g_f03. But then you discover APEX has the oddity that the "checkbox" array only contains values for the checked rows. Thus if you just check "Jones", the length of g_f02 is 1 and it contains only the empno of Jones - while the other two arrays will contain all (14) rows. So for
Post a Comment
Read more

Stop using validations for checking constraints !

By
 If you run your APEX application - like a Form based on the EMP table - and test if you can change the value of Department to something else then the standard values of 10, 20, 30 or 40, you'll get a nice error message like this: But it isn't really nice, is it? So what do a lot of developers do? They create a validation (just) in order to show a nicer, better worded, error message like "This is not a valid department".  And what you then just did is writing code twice : Once in the database as a (foreign key) check constraint and once as a sql statement in your validation. And we all know : writing code twice is usually not a good idea - and executing the same query twice is not enhancing your performance! So how can we transform that ugly error message into something nice? By combining two APEX features: the Error Handling Function and the Text Messages! Start with copying the example of an Error Handling Function from the APEX documentation. Create this function
Post a Comment
Read more