Support array types with Converter

[FabianTerhorst]

Im getting the following error when im query the entity that is using an converter:

 io.objectbox.exception.DbException: Entity is expected to have this constructor: Group(JLjava/lang/String;Ljava/lang/String;Ljava/lang/String;ZLjava/lang/String;ZZZZL[J;)V

The constructor:

public Group(long id, String ..., String ..., String ..., boolean ..., String ...,
            boolean ..., boolean ..., boolean ..., boolean ..., long[] deviceIds)

The Entity converter usage:

@Convert(converter = DeviceIdConverter.class, dbType = String.class)
private long[] deviceIds;

The Converter Class:

public class DeviceIdConverter implements PropertyConverter<long[], String> {

    private static final ByteString SEMICOLON = ByteString.decodeBase64(";");

    @Override
    public long[] convertToEntityProperty(String s) {
        if (s == null) {
            return new long[0];
        }
        try {
            long[] ids = new long[0];
            Buffer buffer = new Buffer();
            buffer.writeUtf8(s);
            long index;
            while ((index = buffer.indexOf(SEMICOLON)) != -1) {
                ids = add(Long.parseLong(buffer.readUtf8(index - 1)), ids);
            }
            return ids;
        } catch (IOException io) {
            io.printStackTrace();
            return new long[0];
        }
    }

    public long[] add(long id, long[] values) {
        long[] anotherArray = new long[values.length + 1];
        System.arraycopy(values, 0, anotherArray, 0, values.length);
        anotherArray[values.length] = id;
        return anotherArray;
    }

    @Override
    public String convertToDatabaseValue(long[] integers) {
        Buffer buffer = new Buffer();
        for (long value : integers) {
            buffer.write(SEMICOLON);
            buffer.writeUtf8(String.valueOf(value));
        }
        return buffer.toString();
    }
}

[greenrobot]

Never tested converters with array types. Could you check if List is working?

[FabianTerhorst]

I have tested it now with List<Long> and its working.

[greenrobot]

Great, I will rename the ticket accordingly to support array types.

[FabianTerhorst]

It looks like even Lists aren´t working as well. Immediately after data is available (list is not null) and the object is getting inserted to the database, the database won´t return any entities anymore in any box.

[greenrobot]

@FabianTerhorst Can you investigate a bit? Is it really related to converters? If not, please open a new ticket.

[FabianTerhorst]

It is. When i remove the converter annotation the app is working again.

[FabianTerhorst]

It is also not depending on the converter. Even when im returning a new arraylist every time the bug occur.

[greenrobot]

@FabianTerhorst You don't have a reproducible test case you can share, I guess?

[FabianTerhorst]

I could try to copy it into a sample add

[FabianTerhorst]

While creating the converter inside the sample project i have noticed that the converter was throwing an exception that wasn´t thrown in the main app. I fixed the converter, copied the fix into the main app and everything was working how expected.

[greenrobot]

@FabianTerhorst Alright. Was the exception swallowed, so you did not notice in the first place?

[FabianTerhorst]

@greenrobot yes, there was no strack trace inside the main app, just the database was not working correctly.

[greenrobot]

@FabianTerhorst I just checked: we have unit tests to ensure exceptions from the converter are thrown from both directions (put and get).

[FabianTerhorst]

Also when the put call is inside an async transaction?

[greenrobot]

In that case TxCallback must be called with an exception. Did that happen?

[greenrobot]

P.S.: Added a unit test for that constellation. Works as expected.

[matecode]

I fixed the converter, copied the fix into the main app and everything was working how expected.

@FabianTerhorst How did you fixed that? I have the same issue with a String Array

This is my converter

public static class ServicesConverter implements PropertyConverter<String[], String> {

        @Override
        public String[] convertToEntityProperty(String s) {
            if (TextUtils.isEmpty(s))
                return null;
            else return s.split(",");
        }

        @Override
        public String convertToDatabaseValue(String[] strings) {
            if (strings != null && strings.length > 0) {
                StringBuilder builder = new StringBuilder();
                for (int i = 0; i < strings.length; i++) {
                    if (i > 0) builder.append(",");
                    builder.append(strings[i]);
                }
                return builder.toString();
            }
            return null;
        }
    }

[FabianTerhorst]

@matecode use List<String> instead.

[Drjacky]

@FabianTerhorst I couldn't figure out. Please look at this question:
http://stackoverflow.com/questions/44082952

[greenrobot]

Does anyone have issues with List types in 0.9.13? If so, please open a separate issue. Thanks!

[greenrobot-team]

Tested using long[] and works as expected (ObjectBox 1.5.0 and 2.0.0-beta).

The easiest way to work around constructor-related DbException when getting/querying entities is to make sure to provide a no-args constructor.

Please submit a new issue if further issues become known.
-ut