I usually use Schemas directly rather than IDL, so apologies if some of
this doesn't map directly.
In a Schema with an optional field, or really any union, the default value
has to be of the first mentioned type. For optional fields this usually
means making the first value the null type and the default value null.
You can instead list the non-null type first and give a default appropriate
for the field type. I'd be surprised if the IDL couldn't also do this.
On Wed, Nov 26, 2014 at 3:56 PM, Niels Basjes <ni...@basjes.nl> wrote:
> Yes, the builders would do that for mandatory (= non-null) fields.
>
> The schemas I'm using have a lot of this pattern
>
> record Thing {
> union { null, Foo } optionalFoo;
>
> union { null, Bar } optionalBar;
>
> }
>
> record Bar {
> union { null, Blabla } optionalBlabla;
> }
>
> etc.
>
> So creating a record with a simple Thing.newBuilder().build() would still
> yield null values for both optionalFoo and optionalBar.
>
>
>
> On Wed, Nov 26, 2014 at 8:58 PM, Sean Busbey <bus...@cloudera.com> wrote:
>
> > What does an example schema look like in this case?
> >
> > Shouldn't the extant builders give you this behavior if you've made the
> > default for the optional fields non-null?
> >
> > --
> > Sean
> > On Nov 26, 2014 11:34 AM, "Niels Basjes" <ni...@basjes.nl> wrote:
> >
> > > Oops,
> > > That should be
> > > public Foo getFoo()
> > > and
> > > public Foo getAlwaysFoo()
> > > ofcourse
> > >
> > > On Wed, Nov 26, 2014 at 6:28 PM, Niels Basjes <ni...@basjes.nl> wrote:
> > >
> > > > Hi,
> > > >
> > > > I have a Java project where I'm using Avro as the serialization
> > > technology.
> > > > I have a deep nested structure and many fields are optional.
> > > >
> > > > Because of the 'random' nature of my application I want to be able to
> > > > simply 'set' a value in that tree easily.
> > > >
> > > > So I want to have a setter in my class that looks like this (Assume
> > > > myStruct is an instance of the 'root' class generated by Avro):
> > > >
> > > > public void setSomething(String value) {
> > > > myStruct
> > > > .getFoo()
> > > > .getBar()
> > > > .getOne()
> > > > .getOther()
> > > > .setSomething(value);
> > > > }
> > > >
> > > > The 'problem' I ran into is that any of the 4 get methods can return
> a
> > > > null value so the code I have to write is really huge.
> > > > For every step in this method I have to build null checks and create
> > the
> > > > underlying instance if it is null.
> > > > I already started writing helper methods to do this for parts of my
> > tree.
> > > >
> > > > To solve this in a way that makes this code readable I came up with
> the
> > > > following which I want to propose to you guys (before I start working
> > on
> > > a
> > > > patch).
> > > >
> > > > My idea is to generate a new 'get' method in addition to the existing
> > > > normal get method for the regular instance of the class.
> > > >
> > > > So in addition to the
> > > >
> > > > public void getFoo() {
> > > > return foo;
> > > > }
> > > >
> > > > I propose to generate something like this as well
> > > >
> > > > public void getAlwaysFoo() {
> > > > if (foo == null) {
> > > > setFoo(Foo.newBuilder().build());
> > > > }
> > > > return foo;
> > > > }
> > > >
> > > > This way the automatically created instance immediately has all the
> > > > defaults I have defined.
> > > >
> > > > Assuming this naming my code will be readable because it will look
> like
> > > > this:
> > > > public void setSomething(String value) {
> > > > myStruct
> > > > .getAlwaysFoo()
> > > > .getAlwaysBar()
> > > > .getAlwaysOne()
> > > > .getAlwaysOther()
> > > > .setSomething(value);
> > > > }
> > > >
> > > > I can create this same effect in my own project code.
> > > > But having this automatically generated by the Avro engine would make
> > > life
> > > > a lot easier.
> > > >
> > > > Is this an idea you guys would consider to have in the main (Java)
> > > > generated code base?
> > > > If so, is the 'getAlways' prefix sensible?
> > > >
> > > > --
> > > > Best regards
> > > >
> > > > Niels Basjes
> > > >
> > >
> > >
> > >
> > > --
> > > Best regards / Met vriendelijke groeten,
> > >
> > > Niels Basjes
> > >
> >
>
>
>
> --
> Best regards / Met vriendelijke groeten,
>
> Niels Basjes
>
--
Sean
