kandrextensions

Useful android extensions, for kotlin based projects

AsyncTask:

fun <T> runAsyncTask(backgroundTask: () -> T?,
                          uiCallback: (T?) -> Unit = {},
                          errorHandler: (Throwable) -> Unit = { throw it})

helper method, which can be used for background work, and replace android asynctasks
    This helper takes three callbacks and uses AsyncTask for beckground work, so, it must be called from the UI thread:

    backgroundTask - will be executed in background thread, returns nullable result

    uiCallback - will be executed in UI thread. Nullable result from background task will be passed to this callback

    errorHandler - any caught error(exception) will be passed into this callback. In case of error, uiCallback will not be called. Raised exception will be passed as an argument

Database

SQLiteDatabase.runTransaction()
    allows write code in transactions without worrying about transaction openning and closing.
    example:
        db.runTransaction{db -> 
            db.rawSql("CREATE TABLE TEST (TEST_COLUMN INTEGER PRIMARY KEY))
        }
        
        
SQLiteDatabase.count()
    return table count
    example:
        db.coun("test_table", "user_id > ?", arrayOf("1"))
        where required is only table name

SQLiteDatabase.optQuery()
    allows optionally pass arguments to database queries
     example: 
        // mSqliteDatabase.query("Users", null, null, null, null, null, null, null)
        mSqliteDatabase.optQuery("Users")
          
        // mSqliteDatabase.query("Users", null, "_id=?", arraOf("5"), null, null, null, null)
        mSqliteDatabase.optQuery("Users", selection = "_id=?", selectionArgs = arraOf("5"))

Cursor accessor functions, which return types, by column name
    
    fun Cursor.getBoolean(name: String): Boolean
    fun Cursor.getString(name: String): String 
    fun Cursor.getNullableString(name: String): String?
    fun Cursor.getInt(name: String): Int 
    fun Cursor.getNullableInt(name: String): Int?
    fun Cursor.getLong(name: String): Long
    fun Cursor.getNullableLong(name: String): Long?
    fun Cursor.getDouble(name: String): Double
    fun Cursor.getNullableDouble(name: String): Double?
    fun Cursor.getFloat(name: String): Float
    fun Cursor.getNullableFloat(name: String): Float?
    fun Cursor.getBoolean(name: String): Boolean
    fun Cursor.getNullableBoolean(name: String): Boolean?
      
<T> Cursor.asList(mapper: (c: Cursor) -> T): CloseableList<T> - wraps cursror with closeable list instance, to access cursor as list
      
      example:
      
      val c = MatrixCursor("column")
      val list = List<SomeDataObject> = c.asList{ SomeDataObject(it.getString("column")) }
      
Cursor.asFinalList() converts cursor to a list instance, takes converter function as an argument. Closes cursor by default

##UI extensions: fun View.isVisible(): Boolean fun View.setGone(gone: Boolean) fun View.setVisible(visible: Boolean)

fun FragmentManager.isFragmentAdded(tag: String) : Boolean
fun FragmentManager.addIfNot(tag: String,  transaction: (FragmentTransaction) -> Unit) : Boolean
 
 Searches fragment by tag. If fragment is not found, starts a new transaction and passes it to the callback. 
 Commits transaction after callback is executed

##Keyboard extensions fun Fragment.hideKeyboard() fun Activity.hideKeyboard() fun View.hideKeyboard()