Question

I have a query statement with a LEFT JOIN in my ContentProvider

the left table is posts and it has a post_id column, the right table is taggings it it has a post_id column as well and I’m doing posts left join taggings on posts.post_id=taggings.post_id

when querying the ContentProvider, if there is no matching row in the taggings table, for some reason the returned value from cursor.getColumnIndex("post_id") is wrong and the int value of the id is always 0.

if there is a matching row in taggings, everything work as expected.

what am I missing here ?

ContentProvider query:

case POSTS:
        qb.setTables(MetaData.TABLE_POSTS

                + " LEFT JOIN " + MetaData.TABLE_TAGGINGS + " ON "
                + MetaData.TABLE_POSTS + "." + MetaData.COLUMN_POST_ID
                + "=" + MetaData.TABLE_TAGGINGS + "." + MetaData.COLUMN_POST_ID
                );
        break;

cursor query statement:

Cursor cursor = context.getContentResolver().query(MetaData.POSTS_URI, 
            null, null, 
            null, MetaData.TABLE_POSTS + "." + MetaData.COLUMN_POST_ID + " DESC");

Answer 1

I fixed that by using setProjectionMap() to map MetaData.COLUMN_POST_ID to MetaData.TABLE_POSTS + "," + MetaData.COLUMN_POST_ID