Custom field converter example for Cupboard

TestStringArrayConverter.java

package nl.qbusict.cupboard;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.test.AndroidTestCase;

import nl.qbusict.cupboard.convert.EntityConverter.ColumnType;
import nl.qbusict.cupboard.convert.FieldConverter;

public class TestStringArrayConverter extends AndroidTestCase {

    public static class TestEntity {
        public Long _id;
        public String[] myStringArray;
    }

    public void testStringArrayConverter() {
        // Note that this converter does not handle escaping commas that are also used
        // as a separator
        FieldConverter<String[]> converter = new FieldConverter<String[]>() {
            @Override
            public String[] fromCursorValue(Cursor cursor, int columnIndex) {
                return cursor.getString(columnIndex).split(",");
            }

            @Override
            public void toContentValue(String[] value, String key, ContentValues values) {
                if (value.length > 0) {
                    StringBuilder sb = new StringBuilder(1024);
                    for (String s : value) {
                        sb.append(s);
                        sb.append(",");
                    }
                    // strip off trailing comma
                    sb.setLength(sb.length() - 1);
                    values.put(key, sb.toString());
                } else {
                    values.put(key, "");
                }
            }

            @Override
            public ColumnType getColumnType() {
                return ColumnType.TEXT;
            }
        };

        Cupboard cb = new CupboardBuilder().
                            registerFieldConverter(String[].class, converter).
                            build();
                            
        cb.register(TestEntity.class);

        TestEntity entity = new TestEntity();
        entity.myStringArray = new String[] {"hello", "world"};
        ContentValues values = cb.withEntity(TestEntity.class).toContentValues(entity);
        assertEquals("hello,world", values.getAsString("myStringArray"));
        MatrixCursor cursor = new MatrixCursor(new String[] {"myStringArray"});
        cursor.addRow(new Object[] {"world,hello"});
        cursor.moveToFirst();
        entity = cb.withCursor(cursor).get(TestEntity.class);
        assertEquals(2, entity.myStringArray.length);
        assertEquals("world", entity.myStringArray[0]);
        assertEquals("hello", entity.myStringArray[1]);
    }
}

using guava here would be really slick too..

public void toContentValue(String[] value, String key, ContentValues values) {
  values.put(key, value == null ? "" : Joiner.on(',').join(value));
}