I am just starting out with mobile development and the data handling for Flex mobile applications seem to be plain horror. I have spent two days on it, tried about 10 different approaches and still can't find a clen working solution.
So i have a TabbedViewNavigatorApplication with many views and subviews. All of them should be able to access the same data that i want to store in a model (so basically they need to access the same model class to add, edit and retrieve some data from there).
I create one instance of a model, pass it as data to all view stacks
If i change something in one view stack and switch to another one, i see the changes and all is fine.
But if I change the model data in one view and restart the application, I see changed data in that view but if i switch to another view, it has the old (unmodified) model. I would assume that the model would be the same instance but apparently each view has its own "model" when saving persistance data.
So how do you manage shared model over all views ? Ideally i would create it once on the first app launch, and then just add / remove items from any view or subview.
Or do i need to use the SQLite for that ? In this case it seems i would need to fetch the data for each view each time a view changes to stay up-to-date with the current data in the database ?
Please help :)
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I'm currently working through my A Level computer science controlled assessment, and am making an application designed to help Scout Leaders manage their group. This is my first time working in Java, SQLite, Android Studio and XML so I've run into a few problems along the way. At this point in time, I'm in the process of creating a login system, part of which involves editing login details. I was wondering if there's a way of loading multiple values from one record into different EditTexts at once, so the user only needs to edit the already-existing username and password, rather than type it in again with a slight edit? Thanks in advance. I didn't think it necessary to include any code in this question, as I'm only looking for an example, however if it would help please don't hesitate to ask - I just couldn't find a guide on this anywhere else.
You retrieve the data into a Cursor via a query that selects the required columns.
You then move to the appropriate row (record) in the Cursor (probably the first and only row).
For each EditText you set the text, using the setText method with the data from the respective column using an appropriate get???? method passing the column offset to the method (e.g. your_cursor.getString(<the_column_offset>)).
Rather than calculating and hard coding an offset, it is more reliable and flexible to use the getColumnIndex(<the_column_name_as_string>) method.
After all have been set you then close the Cursor
Note and would be replaced with respective values specific to the App.
I am new to Google App maker and I don't have a lot of experience with coding either (sorry :/). Since App maker is marked as low-coding app builder tool, I assumed it was not that hard to make a very simple app with it. However, for me it is.
I need to make a simple app for demonstrations purposes only (so Cloud SQL and other complex database solutions are not in my interest here). I want to make it using calculated models (correct me if I am wrong, calculated models are just temporary solutions, since apps need to have like real databases to be fully functional?).
My app is basically made of 2 datas: 1) Employees and 2) Departments
-> Fields for "Employees" are: First name, Last name and Department.
-> Field for "Departments" is just Department name.
My app is supposed to look like this:
1st page: Table with current employees that has a button to add new employee,
2st page: Table with all department names (e.g. marketing, finance...) that has a button to add new department name,
3rd page: Form that opens when I click on add new employee button in which I can insert their first name, last name and from drop down menu choose department,
4th page: Form that opens when I click on add new department button in which I can insert new department name.
5th page: Form (or some other widget, not sure here) that has option to insert first and last name in order to find out what department that employee is assigned to.
I tried to make first 4 pages, but I end up with forms that I cannot insert anything into them. 5th page is still too much for me.
I hope you understand my struggles and if you know how to do it please share your knowledge. Thank you very much!
Calculated models are kind of like SQL views - they are not necessarily for temporary solutions. Every time you load a calculated model the script you write under that model's datasource is ran. That script usually loads data from an external source (I.e. grabbing stock prices from an API, loading data from an external SQL server, or generating random placeholder data).
You could use the cloud SQL models for this application that you are building - your table with all department names that is supposed to be displayed in the second page could just be a cloud SQL table with one single field for a department name.
I suggest you work through the example apps so you can get a better understanding of how the different components work. Here is a link to one for you to get started.
In short, you're going to create a few models to store information (I suggest using cloud SQL as the calculated models will require code whereas cloud SQL is more plug and play through app maker's bindings). Before you create any pages try to lay out how your databases will look as that will dictate how you set bindings or program your scripts.
Asking to completely make what is essentially a combination of the tutorials already provided by Google is pretty counter intuitive - you should ask more specific questions in regards to implementation.
As for App Maker being a low-code environment, that's only partially true. For very, very simple apps (think glorified forms) you will need only a couple lines of code and can probably do everything through drag-and-drop. However, anything more complicated than a simple form will almost certainly require a good chunk of actual code. There are plenty of resources online to learn Javascript.
You might want to try a google partner like AppSynergy for building stuff like this. It might be overkil for what you need (or maybe not if you intend to build a lot more stuff).
I am currently undertaking an exercise to research on a number of JS MV* frameworks and select one that best suits the team's needs. Knockout is one of the contenders that I am learning about.
One of the most important requirements is for changes in the data in a view model to be broadcast to all the views that use such data. For example, lets say we have client details listed in a data grid on a page, clicking on any row in the data grid brings up a pop-up dialog where the user can edit the values of the selected row. When the change is made and the user clicks 'Save', the data is updated in the database. But what we also want is that the change be reflected in the local ko.observablearray and then for any other views that use this 'clients' collection to refresh themselves with the new data. In other words the views must refresh themselves with the data in ko.observablearray rather than get a fresh list from the database.
I have been successful in doing this - have one a single .cshtml file which houses the data grid and a form to create new row in the data grid. In this scenario, the data in the grid refreshes correctly. But when the change happens on a another cshtml file, I am not able to carry these changes across to the other views. Can this be done in knockout and if yes, please point me to an example of how and where this has been done.
I would use a Event aggregator pattern. I have made one for SignalR
https://github.com/AndersMalmgren/SignalR.EventAggregatorProxy
Install usign nuget
Install-Package SignalR.EventAggregatorProxy
If you have no use for SignalR you can then extract the relevant parts from my lib, demo here
http://jsfiddle.net/jh8JV/
I am working on an StoryBoarding application,it is a slide based application in which the authors can put several components like image , sound , captions etc in each of the slide.A collection of slides will make a storyboard.This application will be deployed on a web server (sharepoint + IIS , and php+apache), and several users can collaborate with each other for authoring or reviewing the storyboard.In my application I also want to support auto save ,which will keep on storing the state of the storyboard.User can also save at any point of time by clicking the save button.
I am confused about how to store the state of the storyboard.
1)Presently I am doing this by passing all the storyboard data to a dot net web-service and then that service is storing images,caption etc in their respective tables into a database .
2)Another approach possible is to store the model of the application as a serialized object into the db , which will be more convenient since separating the components of the model (like images,captions etc..) will not be required and also restoring the state of the objects in the application will be easy .
I have two doubts about using approach 2 :-
i) I want the the saved storyboard to load quickly, for which I would like to support the partial so that lighter objects like caption can be loaded quickly but other heavier objects like image,video etc can be loaded on demand. Using approach 2 , do I have to send the whole data in one go or is there way to support partial loading ?
ii) How to implement the auto save feature when using approach 2, for every auto save do I have to send the whole serialized object again back to db or is there a way to send only the changed part of the model to be stored in db .
Please suggest which approach would be better to use for this application , and also answer afore mentioned doubts regarding using approach 2 .
If i would be working on such Application i will use Approach DIVIDE AND RULE, a design seprate logic to save and retrive each components like Images, sound etc, because it can easly handles any modification and enhancement in application,
Another thing is that it will take longer time to save, update and load data from backend if you use approach 2.
I am with approach 1.
Hopes that helps
its said that 1 ViewModel has 1 View.
1 View is for me a UserControl. What if my UserControl has different areas filled with data from different entities, do I have then several Views and need to build several ViewModels?
e.g: I display in a UserControl 3 entities: customer(listbox),order(datagrid),product(datagrid). Each of those "data areas" has add+remove buttons and textboxes to enter data.
Actually each of those "data areas" are put in its own GRID having so the posibility to set a individual datacontext.
1.) Should I now create 3 ViewModels CustomerVM,OrderVM and ProductVM?
2.) Are those 3 "data areas" seen as an own sort of separated View, although I have not put them in 3 UserControls.xaml files ???
3.) When this one UserControl is inside a TabControl`s tabpage where do I load the 3 entities related data? Inside the MainViewModel? I want to show/load that data only when the user clicks the tabheader.
No, you can do all that in the one viewmodel. The job of the viewmodel is to hold the data for the view, and if necessary transform that data so the view can consume it. There is nothing that says a viewmodel has to hold specific types of information, i.e. there are no rules that state "it may only hold customer info and not order info".
Having said that, there is also no reason why the viewmodel cannot be consumed by several different views (give them all different instances, of course) - this would show that you have a good separation of concerns between your views and viewmodel. Personally, i code my viewmodels so that they have no idea that the view exists. There is also no reason why the view has to consume everything that the viewmodel exposes, although binding a CustomerView to a CustomerOrderProductViewModel is going a little too far.
Edit: let me explain that last paragraph a little more.
Example 1: i have a new V which shows customer information, and i have an existing VM which has customer info AND order info
I would be reluctant to use this VM for this V, because while it does have the client info i need, it has too much info - i'm using the VM out of the context is was originally intended for.
Example 2: i have a VM that contains full client info, like their postal and residential address, their phone numbers, their girlfriend's names*, and a bunch of other client type info. I have a V which shows the client's name, birthday, and maybe two other properties.
I would consider using that VM for that V, this illustrates my point that the V doesn't have to show all the info contained within the VM. This concept becomes more apparent when you change the V (as in, do some maintenance and change the UI of the view, because someone has decided that they want a bunch of fields removed and now they want to represent the client's age as an image) - i can still use the same VM, and just change the V (i could use a ValueConverter to represent the age as an image, thus avoiding a change to the VM).
At what point would i stop using the current ClientViewModel, and write a new one that was more specific to the needs of the modified ClientView?
There is no clear cut answer to that - it depends on the amount of time i have available to do the changes, the amount of time available for testing, and the trade-off in complexity between using a full blown Client object for the VM, and writing a new leaner version of the Client object while still retaining the old one.
*that should be a collection of independant objects incorporated in the client object, but just work with me here it's a made up example :)