Thanks for the explanations, I'll go for wrappers but wanted to get
some advice first.
So am I to understand that there is no way of having optional values
as you'd get the following?
Exception in thread "main" java.lang.NullPointerException
at org.apache.avro.io.BinaryEncoder.writeString(BinaryEncoder.java:133)
at
org.apache.avro.generic.GenericDatumWriter.writeString(GenericDatumWriter.java:176)
So for an example I would need to put a NULL in an Enum to allow for
explicit indication of the Enum not being set?
I am only using the example code so maybe I am using the wrong writers
and should be doing something more specific...
Thanks,
Tim
On Mon, Aug 2, 2010 at 8:06 PM, Scott Carey <[email protected]> wrote:
> Right now, defaults are for readers to read data written with a differing
> schema. This is for schema evolution, not for making writing easier.
>
> We could add a feature to a DatumWriter in the Java API to set defaults
> during writing if the field is null, or a method on a SpcificRecord that will
> set defaults.
> However, there is some safety provided by this -- it catches users who forget
> to set a field before it is written incorrectly.
>
> I recommend creating a wrapper class or static helpers that handle your type
> construction and/or field manipulation. This does two things: It abstracts
> your code from the exact SpecificRecord implementation details, and provides
> you with the ability to control specific requirements for construction and
> use of your objects. In this way you can control how truly required fields
> are differentiated from truly optional fields.
>
> "default" in avro is not there to distinguish 'optional' from 'required'
> fields -- it is there to manage schema evolution.
>
> On Aug 2, 2010, at 9:51 AM, Tim Robertson wrote:
>
>> Hi all,
>>
>> I am doing the protocol compilation to Java using the maven plugin and
>> looking for an explanation on the default values please.
>>
>> http://www.mail-archive.com/[email protected]/msg04063.html
>> tells me that defaults aren't used at write time, but it means that I
>> have to initiate all the Strings with "=new Utf8();" each time I
>> create a message payload - is this correct?
>>
>> If I set them to null, then I always see:
>> Exception in thread "main" java.lang.NullPointerException
>> at org.apache.avro.io.BinaryEncoder.writeString(BinaryEncoder.java:133)
>> at
>> org.apache.avro.generic.GenericDatumWriter.writeString(GenericDatumWriter.java:176)
>>
>> I wonder the reasoning behind not initializing with null types (e.g.
>> for String using new Utf8()) in the client generation. It means I
>> either need to modify the generated sources, or wrap them in some kind
>> of factory/builder right? Is that a common practice for avro or are
>> others doing something different?
>>
>> Any recommendations for best use greatly appreciated. Currently in my
>> working test I have to:
>>
>> Event e = new Event();
>> e.level=LEVEL_TYPES.DEBUG; // no auto ENUM default?
>> e.objectType = OBJECT_TYPES.NAME_USAGE;
>>
>> e.sourceComponentType=SOURCE_COMPONENT_TYPES.CHECKLIST_HARVESTER;
>> e.agentId=new Utf8("Hi list");
>> e.count=0;
>> e.instanceId=new Utf8("127.0.0.1:7004");
>> e.message=new Utf8();
>> e.objectId=new Utf8();
>> //e.sensitive=false; // works because is a primitive
>> e.sessionId=new Utf8("dysAw231");
>> e.sourceId=new Utf8();
>> e.userId=new Utf8();
>> logger.info(e, false);
>>
>>
>> Thanks,
>> Tim
>
>
