mongoTemplate: custom converter with non standard objects - spring

Question

I found an issue when using a custom converter.
Let's say my to objects are:
public class Foo {
private String id;
private Bar bar;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public Bar getBar() {
return bar;
}
public void setBar(Bar bar) {
this.bar = bar;
}
}
public class Bar {
private String id;
private String property;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getProperty() {
return property;
}
public void setProperty(String property) {
this.property = property;
}
}
If they are inserted into the MongoDB, everything works fine, as long as no custom converter is involved.
Bar bar = new Bar();
bar.setProperty("Test");
Foo foo = new Foo();
foo.setBar(bar);
mongoTemplate.insert(bar);
mongoTemplate.insert(foo);
Results:
{
"_id" : {
"$oid" : "51a346059f2c9d656019798e"
},
"_class" : "Bar",
"property" : "Test"
}
{
"_id" : {
"$oid" : "51a346059f2c9d656019798f"
},
"_class" : "Foo",
"bar" : {
"_id" : {
"$oid" : "51a346059f2c9d656019798e"
},
"property" : "Test"
}
}
Now I wrote a custom converter, cause Foo needs to be stored in a special way.
public class FooWriteConverter implements Converter<Foo, DBObject> {
#Override
public DBObject convert(Foo source) {
DBObject dbo = new BasicDBObject();
dbo.put("id", source.getId());
dbo.put("bar", source.getBar());
return dbo;
}
}
Now I get this error.
Caused by: java.lang.IllegalArgumentException: can't serialize class Bar
So, it looks like I can't fall back to the default conversion for properties of an object, that is converted using a custom converter?!
Any useful solutions instead of doing all conversion manually?

Answer 1

In order to use default conversion for properties in custom converter you need a MongoConverter class help.
public class FooWriteConverter implements Converter<Foo, DBObject> {
private MongoConverter mongoConverter;
public FooWriteConverter(MongoConverter mongoConverter) {
this.mongoConverter = mongoConverter;
}
#Override
public DBObject convert(Foo source) {
DBObject dbo = new BasicDBObject();
dbo.put("id", source.getId());
DBObject bar = new BasicDBObject();
mongoConverter.write(source.getBar(), bar);
dbo.put("bar", bar);
return dbo;
}
}