ViewModel

ViewModel

In MVVM the ViewModelprocesses data for the views, the view can call methods on its ViewModel - not the other way around. The View can react to changes made through the ViewMode by observing its LiveData objects.

The ViewModel communicates with the Repositories to get the Data and passes them to the View.

And that's how it is implemented in the App.

Each fragment / activity has its own ViewModel class (FragmentHome -> ViewModelHome)

ViewModelHome

Extends : ViewModel

Since FragmentHome doesn't have much logic this mostly passes data between FragmentHome and LocalMapsRepository

Methods

Name	Returns	Parameters	Description	Notes
init()	void		initializes the LocalMapsRepository and gets the LiveData object with the local files from it
getLocalMapFiles()	LiveData<ArrayList>, a live data object which can be observed by the view		Getter for the localMapFiles LiveData Object
deleteLocalMapFile(int)	void	int, position of the File to be deleted	Calls LocalMapsRepository.deleteLocalMapFileAt()
chooseMapAt(int)	void	int, the position of the chosen File	Calls LocalMapsRepository.chooseMapAt()

ViewModelOptions

Extends : ViewModel The FragmentOptions displays and alters data from UserPreferences

Methods

Returns	Parameters	Description	Notes
void	SharedPreferences from the App	Called at app start by MainActivity, gets the saved data from the SharedPreferences
String, the user ID		Getter for the user ID
true, if enabled false if not		Getter for the darkmode boolean
void	true, to enable false, to disable	Setter for the darkmode boolean, changes value in SharedPreferences too
void	String, the user ID	setter for the user ID,, changes value in SharedPrefs too

ViewModelMainActivity

Extends : ViewModel Initialized at App start by the MainActivity.

Methods

Name	Returns	Parameters	Description	Notes
init(SharedPreferences)	void	SharedPreferences from the App	Called at app start by MainActivity, gets the saved data from the SharedPreferences
HttpGetIdFromServer()	void		Gets the User ID from the server	Note : this shouldn't be in the ViewModel
isDarkmodeEnabled()	true, if enabled else false		Getter for the darkmode boolean
createOhdmDirectory()	void		Creates the OHDM dir at first start of the app

ViewModelNavigation

Extends :ViewModel

Methods

Name	Returns	Parameters	Description	Notes
getLastKnownLocation(Context)	Location, an Object which contains Latitude and Longitude of the last known location of the device	Context, needed to check the permissions	Gets the last known location of the device

ViewModelRequestNewMap

Extends : ViewModel Initialized at App start by the MainActivity.

Methods

Name	Returns	Parameters	Description	Notes
getDatePickerValuesAsString(DatePicker)	String, a String build from the DatePicker input	DatePicker, the DatePicke where will be read from	Building a formatted String (yyyy-mm-dd), as its needed by the server
getCoordinatesAsString(EditText, EditText, EditText, EditText)	String, coordinates as String	The four edit texts where the user inputs latitudes and longitudes	Building a String out of the coordinates, as expected from the server
buildParamsString(String, String, String)	String, the parameter String as expected by the server	the name, coordinates and date as strings	Builds a String as accepted by the server example: name=mapname &coords=13.005,15.123_13.005, 15.123_13.005,15.123_13.005,15.123_13.005,15.123&date=2117-12-11&id=1JWd3wc l
checkForNullCoordinates(Context, EditText, EditText, EditText, EditText)	true, if every coordinate was set, false if there are empty EditText's	Context, to make Toasts, and the four EditText's	Check if the user entered all necessary coordinates
checkForNullName(Context, EditText)	True, if a name was given.	Context to make a toast, EditText where the user inputs the name	Check if a name was entered by the user
RequestMap(String)	void	The paramsString	Makes a Http request with the paramsString	Note : this should be moved out of the ViewModel

ViewModelRequestStatus

Extends : ViewModel Initializes the HttpRepository to get the /requestById string as response and makes it available to be observed by the FragmentRequestStatus, Manages the communication between the two. Process the String for the FragmentRequestStatus Provides observable booleans to enable FragmentRequestStatus to show different connection states (Like: No Connection, No Requests, Connected ...)

Methods

Name	Returns	Parameters	Description	Notes
processString(String)	void	String, the server response	Processes the String the server returned as response. Checks if its valid , the builds an ArrayList from it which can be displayed by the view.
getResponse()	LiveData		Gets the response from the HttpRequest as String, this will e observed by the view. As soon as the value changes the View will call processString() with it and the which will the alter the value of {@link requests}, and/or the Booleans which again are observed by the views
getRequests()	LiveData<ArrayList>, the ArrayList processString() builds from the server response as observable LiveData		Provides a Live Data object to the view, which will get notified as soon as it changes. * It will change when there came a valid response from the server by the processString() method
refresh()	void		Lets the HttpRepository make a server request again, as soon as the response changes everyone will get notified through the LiveData

There are Four more methods in this view model getNoConnectionBoolean, getRequestsReceivedBoolean, getNoRequestsForIdBoolean, and getConnectionBoolean. The all do pretty much the same, that's why didn't wanted to mention them individually in the table above.

They all provide a LiveData which can be observed by the View. The value of them will be changed by the processString() method depending on the strings content, They enable the View to change its appearance depending on the Servers response .

ViewModelDownloadCenterAll

Extends : ViewModel

Methods

Name	Returns	Parameters	Description	Notes
downloadMap(RemoteFile)	void	File to be downloaded	Starts the download of a RemoteFile via the FtpRepository
refresh()	void		Triggers a refresh of ALL data manged by the FtpRepository also for the data displayed by the FragmentDownloadCenterCategories
init()	void		Initializes all necessary Objects for the first time
getAllMaps()	LiveData<ArrayList>		Returns the allMaps LiveData Object
getMostRecentMaps()	LiveData<ArrayList>		Returns the mostRecentMaps LiveData object

ViewModelDownloadCenterCategories

Extends : ViewModel Initialized at App start by the MainActivity.

Methods

Name	Returns	Parameters	Description	Notes
downloadMap(RemoteFile)	void	File to be downloaded	Starts the download of a RemoteFile via the FtpRepository
refresh()	void		Triggers a refresh of ALL data manged by the FtpRepository also for the data displayed by the FragmentDownloadCenterAll
init()	void		Initializes all necessary Objects for the first time
getDirectories()	LiveData<ArrayList>		Returns the directories LiveData Object
getDirectoriesContents(String)	LiveData<HashMap<String, ArrayList>>>		Returns the directoriesContents LiveData object