I am trying to write a simple content provider and populate a ListView using these references:
https://developer.android.com/reference/android/app/ListActivity.html
http://www.newthinktank.com/2015/01/make-android-apps-21/
I looked at this thread but it does not seem to be my issue:
SimpleCursorAdapter to populate ListView
The database seems to work, but when I try to bind to my ListView it gives an error of a missing column '_id', but I have it since I can log the contents of the database without problems. Code snippets below:
Logging the database (This WORKS!):
public void logAllPatients() {
// Projection contains the columns we want
String[] projection = new String[]{"id", "name"};
// Pass the URL, projection and I'll cover the other options below
Cursor cursor = resolver.query(CONTENT_URL, projection, null, null, null);
// Cycle through and display every row of data
if (cursor.moveToFirst()) {
do {
String patientList = "";
String id = cursor.getString(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
patientList = patientList + id + " : " + name + "\n";
Log.d(TEST_CONTENT_PROVIDER, patientList);
} while (cursor.moveToNext());
}
}
trying to populate the listview (missing column?, why)?
private void bindAllPatients() {
try {
// Projection contains the columns we want
String[] projection = new String[]{"id", "name"};
Cursor cursor = resolver.query(CONTENT_URL, projection, null, null, null);
if (cursor != null) {
startManagingCursor(cursor);
cursor.moveToFirst();
// Now create a new list adapter bound to the cursor.
// SimpleListAdapter is designed for binding to a Cursor.
ListAdapter adapter = new SimpleCursorAdapter(
this, // Context.
android.R.layout.two_line_list_item,
cursor, // Pass in the cursor to bind to.
new String[]{"id", "name"}, // Array of cursor columns to bind to.
new int[]{R.id.my_id, R.id.my_name}, 0);
// Parallel array of which template objects to bind to those columns.
// Bind to our new adapter.
setListAdapter(adapter);
cursor.close();
}
} catch (Exception e) {
Log.e(TEST_CONTENT_PROVIDER, e.toString());
}
}
The output log:
D/GMO_CONTENT_PROVIDER: 9 : Joe
D/GMO_CONTENT_PROVIDER: 10 : Mary
E/GMO_CONTENT_PROVIDER: java.lang.IllegalArgumentException: column '_id' does not exist
here's the database creation:
private SQLiteDatabase sqlDB;
static final String DATABASE_NAME = "myPatients";
static final String TABLE_NAME = "patients";
static final String CREATE_DB_TABLE = "CREATE TABLE " + TABLE_NAME +
"(id INTEGER PRIMARY KEY AUTOINCREMENT, " + " name TEXT NOT NULL);";
// bunch of code
@Override
public void onCreate(SQLiteDatabase sqlDB) {
try {
sqlDB.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
sqlDB.execSQL(CREATE_DB_TABLE);
} catch (Exception e) {
Log.e(TEST_CONTENT_PROVIDER, e.toString());
}
}
and the query override, which works!
@Nullable
@Override
public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
queryBuilder.setTables(TABLE_NAME);
switch (uriMatcher.match(uri)) {
case uriCode:
queryBuilder.setProjectionMap(values);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
Cursor cursor = queryBuilder.query(sqlDB, projection, selection, selectionArgs, null, null, sortOrder);
cursor.setNotificationUri(getContext().getContentResolver(), uri);
return cursor;
}
any help is greatly appreciated!
The correct answer:
Android column '_id' does not exist?
"SimpleCursorAdapter requires that the Cursor's result set must include a column named exactly "_id"."