android.database.sqlite.SQLiteException: unknown error (code 0 SQLITE_OK[0]): Unable to convert BLOB to string

[EMaksymenko]

When I execute queryRaw and tabe has BYTE_ARRAY fields, iterator will fail in StatementExecutor with:
android.database.sqlite.SQLiteException: unknown error (code 0 SQLITE_OK[0]): Unable to convert BLOB to string

Because for Blob it should be getBytes which internally uses getBlob instead of getString used.

Is it possible to fix this or any workarounds available?

[EMaksymenko]

I see there is a methos to avoid reading all as strings, but what is a common pattern to get dataTypes for it?

/**
 * Similar to the {@link #queryRaw(String, RawRowMapper, String...)} but uses the column-types array to present an
 * array of object results to the mapper instead of strings. The arguments are optional but can be set with strings
 * to expand ? type of SQL.
 */
public <UO> GenericRawResults<UO> queryRaw(String query, DataType[] columnTypes, RawRowObjectMapper<UO> mapper,
		String... arguments) throws SQLException;

[EMaksymenko]

I am trying to add UNION support by preparing two statemens and adding text UNION between them.
What is the correct way then to map result on dao entity?
Simple queryRaw is very inefficient, because map 600 000 rows with 30 columns via String

How can I inject standard object mapping to raw query, or how can I inject subselect statement with word UNION between WHERE and ORDER BY test of the first query builder to use standard query method?.

[j256]

I see there is a methos to avoid reading all as strings, but what is a common pattern to get dataTypes for it?

Good question. That should be in javadocs. On the DAO is a getTableConfig() method which has a getFieldConfigs() method. Each FieldConfig has a getDataType() method. Typically you specify the fields that you want manually and then the data-types you specify are used to convert the SQL result field into the returned Java object.

It would be relatively easy to have a getDataTypes() method on DAO. I'll add that.

[EMaksymenko]

Please add also a union method in QueeyBuilder which which accepts another QueriBuilder for union, adds it to the list similar to joinList and adds statement of each added builder after having, before orderBy.

It is a very easy change, and it will add UNIONs support natively.

I can give you my code example of CustomQueryBuilder, which I have made, if you wish.