I am developing a Windows Phone 7 silverlight application but, i can't use the session values to "navigate" between different pages on windows phone 7.
I also used "Isolated Storage" but i couldn't get the values.
This sample shows some persistence mechanisms:
http://www.scottlogic.co.uk/blog/colin/2011/05/a-simple-windows-phone-7-mvvm-tombstoning-example/
You can also use Query Strings to pass information between two pages. The values that make up a query string are appended to the URI.
Personally, I have a centralised controller class that gets instantiated with the main App class. Any values that need passing are placed in here, in one way or another.
Thanks Adam Houldsworth for your response, it really helped me. However i found a simpler solution.
We can create a Global Variables Class in "App.xaml.cs" file and put the variables in it. The class is accessible from everywhere.
Example:
public static class GlobalVariables
{
public static string my_string = "";
public static int my_int = "";
}
Then we access the Global Variables class like this:
project_Name.GlobalVariables.variable_name;
Related
I have the following situation: I have some models in which I deserealize data from XML (which was received by GET request). Then i want to use these objects everywhere in app. How to store them? I don't want to store this data in local databases.
P.S. I use MVVM
Here are your options as I see it:
If you need it to persist when the app is closed
Sqlite and store it locall. Sqlite isn't that scary if that's what you're worried about. Here's a good blog post on how to handle it in a really easy way: Super Simple Sqlite
Write to a file like #Jason suggested.
Use a key-value storage like #apineda suggested.
For all of these, you can use them WITH what I explain below.
If you do not need it to persist
Create a Store that has a property for your collection of data. Then access that Store class from your ViewModels or another Service layer or whatever you like. This can be combined with any of the above mentioned long-term storage strategies. If you need your Store to persist, consider using Dependency Injection to inject it into your ViewModels that require it, or store it as a reference in your App if you're using Xamarin.Forms or some Singleton.
Here's an example:
public class ItemStore
{
public List<Item> DataItems { get; set; }
}
Then set a store property in your App.cs:
public class App : Application
{
...
public ItemStore ItemStore { get; set; }
...
}
Then reference it from your ViewModel:
((App)App.Current).ItemStore.DataItems = yourParsedCollection;
And you can get it in the same way.
You can save your data in a file and load from here every time you want . It's really fast if a data is only one xml file.
Take a look Saving and Loading Files
https://developer.xamarin.com/guides/xamarin-forms/application-fundamentals/files/
I have defined a class like this:
Class Foo
Public SomePublicProperty
Public Function init(p_somePublicProperty)
set init = Me
SomePublicProperty= p_somePublicProperty
End Function
End Class
And then consumed that in my global.asa Application_OnStart lke this:
Dim fooInstance
Set fooInstance = New Foo.init("Some data")
fooArray = Array(fooInstance)
Application("fooArray") = fooArray
Which works fine but when i get the value back out of the application store on another page i can't get at the property...
fooArray = Application("fooArray")
fooArray(0).SomePublicProperty 'This line returns an error - Object doesn't support this property or method
I have tried putting the class definition into the second page, but it doesn't help.
What have I missed?
I have just found this question. Am I right in assuming the same rule re serialization applies equally to the Application object? and so i shouldn't try and do this?
Unfortunately you can't do this, here is a the best explanation I could find as to why;
From Can I store VBScript class objects in a Session variable?
This is because VBS classes are NOT true classes. They are really just in-memory collections of info, and there is no way to guarantee (for example) that an instance that is stored in one page will even come close to matching the class definition in another page.
This is not the same as using Server.CreateObject() COM objects which can be stored and retrieved from both the Application and Session objects.
You have a couple of options;
Serialise the object yourself, in a structured string then use this to de-serialise the object when needed.
Create a COM wrapper for your VBScript class and stop using Class statement altogether. As COM objects can be stored in Application and Session objects this should work as long as the COM class is single threaded.
Convert your class into an Array and use this instead.
Useful Links
Application Object (IIS)
Setting the Scope of COM Objects in ASP Pages - Giving an Object Application Scope
Am having problems understanding where classes should be kept in CI. I am building an application that describes / markets mobile phones.
I would like for all of my functions (i.e. getphone, getdetails etc.) to reside in one class called Mobile - I understand that this file should be called Mobile.php and reside in the controllers folder.
Can I then have multiple functions inside Mobile.php? E.g.
public function getphone() {
xxx
xx
xx
}
public function getdetails() {
xxx
xx
xx
}
Or do I need to put each function in its own class?
I'd really appreciate looking at some sample code that works. I've been going through the documentation and google for a few hours, and tried all sorts of variations in the URL to find a test class, but without much luck! I've even messed around with the routes and .htaccess...
All I am trying to achieve is the following:
http:///model/HTC-Desire/ to be re-routed to a function that accepts HTC-Desire as a parameter (as I need it for a DB lookup). The default controller works fine, but can't get anything to work thereafter.
Any ideas?
Thanks
Actually it works like this:
Controllers and Models go to their perspective folders as you know it
If you want to create functions that are not methods of an object, you must create a helper file. More info here :
http://codeigniter.com/user_guide/general/helpers.html
Now if you want to create your own datatypes (classes that don't extend Models and Controllers), you add them to the library folder. So if let's say you want to create a class "Car" you create this file:
class Car{
function __construct(){}
}
and save it in the libraries folder as car.php
To create an instance of the Car class you must do the following:
$this->load->library('car');
$my_car = new Car();
More information on libraries here:
http://codeigniter.com/user_guide/general/creating_libraries.html
Yes, you can have as many functions in a controller class as you'd like. They are accessible via the url /class/function.
You can catch parameters in the class functions, though it's not advisable.
class Mobile extends CI_Controller{
public function getPhone($phoneModel=''){
echo $phoneModel;
//echo $this->input->post('phoneModel');
}
}
http://site.com/mobile/getPhone/HTC-Rad theoretically would echo out "HTC-Rad". HOWEVER, special characters are not welcome in URL's in CI by default, so in this example you may be met with a 'Disallowed URI characters" error instead. You'd be better off passing the phone model (or any other parameters) via $_POST to the controller.
Classes can exist both as Controllers and Models, as CodeIgniter implements the MVC pattern. I recommend reading more about that to understand how your classes/functions/etc. can best be organized.
Off the top of my head, Pyro CMS is an application built with CodeIgniter and the source code is freely available. I'm sure there are others.
I think it's best you handle it from one perspective, that is; create a utility class with all your functions in it.
The answer to the question of where to put/place the class file is the "libraries" folder.
This is clearly stated in the documentation. Place your class in the libraries folder.
When we use the term “Libraries” we are normally referring to the
classes that are located in the libraries directory and described in
the Class Reference of this user guide.
You can read more on creating and using libraries Creating Libraries — CodeIgniter 3.1.10 documentation
After placing the newly created class in the libraries folder, to use just simply load the library within your controller as shown below:
$this->load->library('yourphpclassname');
If you wish to receive several arguments within you constructor you have to modify it to receive an argument which would be an array and you loading/initialization would then be slightly different as shown below:
$params = array('type' => 'large', 'color' => 'red');
$this->load->library('yourphpclassname', $params);
Then, to access any of the functions within the class simply do that as shown below:
$this->yourphpclassname->some_method();
I hope this answers your question if you have further question do leave a comment and I would do well to respond to them.
There are a set of common pages that I want to use in multiple projects. Hence, I want to build a class library with those pages. The problem is I am not able to pass objects using NavigationService.Navigate(new Uri("/Common;component/SomeName.xaml", UriKind.Relative)); method.
I know I can pass querystring. What I would like to know is...
Is there any limit to the number of strings you can pass in the querystring?
Is there any length limitation of the querystring?
Or better still,
Is there a better way of passing objects from an application to the pages inside a different class library?
About the question "is there a better way". In addition to the solution you've mentioned some people like to use the app's state to pass parameters between objects. For example:
PhoneApplicationService.Current.State["parameter"] = param;
var parameter = PhoneApplicationService.Current.State["parameter"];
Another option is to use a shared class. With complex objects I find it often easiest to use a static public member in a class which can be accessed from both of the projects.
Note that if you choose to use the query string navigation, some special characters in the query string may cause problems. If you can't control the content of the data which is passed between the pages, the shared class -solution is probably better for you. For example in one of our applications we're passing a web site's name in the query string. There's situations where those names can contain a '&' -character (like H&M) and if it does, the query string will break.
When navigating, if building the query strings gets cumbersome, you may check out the Caliburn.Micro and the Uribuilder class in it. It allows you to navigate with a rather nice (and fluent) syntax:
navigation.UriFor<CandidateDetailsPageViewModel>()
.WithParam(x => x.CandidateId, candidate.Id)
.Navigate();
After navigation, the TryGetValue-method can be rather useful when parsing the parameters:
String parameter;
NavigationContext.QueryString.TryGetValue("Parameter", out parameter)
More details for NavigationContext.QueryString is available from MSDN.
To answer your questions:
No there is no limit to the number of strings you can pass in a qyerystring
I believe the answer to this may be yes. I believe the standard is to have a url of < 2000 characters
For small items I usually just pass a query string to my pages. For more complex cases I have a shared static Domain class that both libraries reference. Then I can just access this variable statically really easily.
It appears I can use the .Where, .First, etc linq expressions in a Windows Phone 7 class library, but not Contains or FindIndex. Are they really not available at all, or is there something else I need to include to access them?
You should be able to use Contains, but FindIndex isn't part of LINQ - it's a method on List<T> normally. However, it's not part of List<T> in Silverlight.
If you're having trouble with Contains, please show a piece of code which is failing.
Contains already exists in WP7
System.Linq.Enumerable.Contains
For FindIndex, a work arround like this should be sufficient
var index = YourList.IndexOf(YourList.FirstOrDefault(selector));
For FindIndex, you can create the method in a class helper:
public static int FindIndex<TSource>(this List<TSource> list, Func<TSource, bool> match)
{
return list.IndexOf(list.FirstOrDefault(match));
}
Then it will work normally.