How to track individual markers to update entry in SQLite

Question

My app allows a user to tape on a cross hair in the center of the map and then add a marker. The marker lat, lng as well as name are saved to a database and thats working fine. I dont add an id as my database adds the id.

public long addEntry(String theLabel, String theArea, String theLat, String theLng) {
    ContentValues contentValues = new ContentValues();
    contentValues.put(KEY_NAME, theLabel);
    contentValues.put(KEY_AREA, theArea);
    contentValues.put(KEY_LAT, theLat);
    contentValues.put(KEY_LNG, theLng);
    return mySpotsDatabase.insert(DATABASE_TABLE, null, contentValues);

}

All good so far and on subsequent loads of the map I get the data from the SQLite database and populate the map with the markers. When I do the retrieval I also include the id of the SQlite entry.

public Cursor getAllData() {
    String [] columns = new String [] {KEY_ROWID, KEY_NAME, KEY_AREA, KEY_LAT, KEY_LNG};
    Cursor c = mySpotsDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    c.moveToFirst();
    return c;
}

And in my maps page

 MySpotsDatabase spotDatabase = new MySpotsDatabase(MyMap.this);
        spotDatabase.open();
        if (spotDatabase.getNumRows() == 0)
            spotDatabase.addEntry("MarkerTitle", "One", myLatitude.toString(), myLongitude.toString());
        spotDatabase.close();

        spotDatabase.open();
        myDataC = spotDatabase.getAllData();
        do {
            dataprovider = new MarkersDataProvider(myDataC.getString(0), myDataC.getString(1), myDataC.getString(2), myDataC.getString(3), myDataC.getString(4));
            arrayList.add(dataprovider);
        } while (myDataC.moveToNext());
        spotDatabase.close();

Again all good so far, BUT now I want to update the marker if the user drags it to another location or if they want to update the title label.

HOW do I set, get and restore a individual marker and write its updated lat, lng, and name back to the SQLite database. THE WRITING BACK to the SQLite database is trivial and I have that sorted, but I need to know which entry in the SQLite database I need to update.

SO I am trying to find a way to grab the _id that I read from the database for each marker and keep that reference with its marker so I can update the database when needed.

ATTEMPT I tried was setting the marker title to the _id but that gives me a null reference for some reason

LatLng newMarker = new LatLng(myLat, myLng);
                        MarkerOptions newOptions = new MarkerOptions();
                        newOptions.position(newMarker);
                        int lastEntry = arrayList.size()-1;
                        String rowID = arrayList.get(lastEntry).getRowID();
                        newOptions.title(rowID);
                        newOptions.draggable(true);
                        String theSnippet = "Marker id: " + arrayList.get(lastEntry).getRowID() + "\nLat: " + String.valueOf(myLat) + "\nLng: " + String.valueOf(myLng);
                        newOptions.snippet(theSnippet);
                        myMap.addMarker(newOptions);
                        Snackbar.make(findViewById(R.id.myMapCoordinatorLayout), rowID + " " + beforeCount + " " + afterCount , Snackbar.LENGTH_INDEFINITE).show();

Looking at hashmaps but unsure if thats the right solution. I will keep digging as maybe storing the _id in the title might still work if I can sort out why its giving me a null reference.

timv · Answer 1 · 2017-08-31T01:53:44.527

SO I have solved the issue of the null reference with GrAnd's answer.

Get gererated ID from inserted row

Here is my line I amended to get the row id:

int newRowID = (int) addToDB.addEntry("New Marker", "One", (String.valueOf(myLat)), (String.valueOf(myLng)));

Still unsure if storing the ROWID in the title is the best way ahead and if I find a better solution I will update my answer.

I also worked out that my dataprovider class was not returning the string value of rowid so it was a rookie mistake on my part.

public class MarkersDataProvider {

private String rowID;
private String name;
private String area; // not used but will be later on.  Just set to "one" for now
private String lat;
private String lng;

public MarkersDataProvider(String rowID, String name, String area, String lat, String lng)
{
    this.setRowID(rowID);
    this.setName(name);
    this.setArea(area);
    this.setLat(lat);
    this.setLng(lng);
}

public String getRowID()
{
    return rowID;
}
public String getName()
{
    return name;
}
public String getArea()
{
    return area;
}
public String getLat()
{
    return lat;
}
public String getLng()
{
    return lng;
}


// never set the rowID as it is generated by the database and I only read it so
// I can reference it in updating and deleting markers

public void setRowID(String rowID)
{
    this.rowID = rowID;
}
public void setName(String name)
{
    this.name = name;
}
public void setArea(String area)
{
    this.area = area;
}
public void setLat(String lat)
{
    this.lat = lat;
}
public void setLng(String lng)
{
    this.lng = lng;
}

SO my plan is to not show the marker title in the info window so that the title can store the row id.

How to track individual markers to update entry in SQLite

1 Answers1