Re: groovy 4 ginq

"I know EOF of the olden times had an LDAP adapter..."

Wow, that brings back unpleasant memories...  Speaking of EOF (and I don't
want to hijack this thread, so feel free to reply in a new one), how long
is Cayenne going to support EOModels? It isn't a lot of baggage that is
carried around, but still baggage.


On Thu, Dec 30, 2021 at 4:12 AM Andrus Adamchik <[email protected]> wrote:

> Not so much of a connector issue, but more of a conceptual limitation.
> Relational backend is implied across the stack, from mapping (FKs, joins)
> to query translation. I know EOF of the olden times had an LDAP adapter,
> and there are JPA engines for NoSQL DBs, but all appear to be really leaky
> abstractions.
>
> If we are to dig in this direction, we will need to start with a model of
> "universal mapping".
>
> Andrus
>
>
> > On Dec 30, 2021, at 4:54 AM, Aristedes Maniatis <[email protected]>
> wrote:
> >
> > Not that I have a need for it, but how pluggable is the JDBC connector
> part of Cayenne? That is, could the backend be easily exchanged for json or
> some other data source, even if only in a read-only way? Could also be an
> interesting way to demonstrate Modeler to new users...
> >
> >
> > Ari
> >
> >
> > On 30/12/21 1:24am, Andrus Adamchik wrote:
> >> An idea of in-memory query evaluation fits Cayenne to a degree. Though
> it is limited to what we already do with in-memory expression-based
> filtering and sorting. A more fancy data transformation (even a simple
> "toUpperCase" from your example) runs against the basic ORM philosophy
> ("toUpperCase" would be a property that does not directly correspond to a
> value in DB).
> >>
> >> I solved it for myself by splitting use cases in two groups:
> >>
> >> 1. "Data as object graph" where Cayenne is appropriate (most cases)
> >> 2. "Data as data" with extra "plasticity" of changing any piece of data
> on the fly
> >>
> >> For #2 sometimes I'd use Cayenne (e.g. column queries, SQLSelect), but
> most often I'd go with DFLib. The main data object in it is a DataFrame
> (essentially a dynamic in-memory table). DataFrame is not tied to a
> specific object structure, and can be dynamically transformed (columns
> added, removed, changed, rows filtered, joins, unions, etc.). DFLib can do
> what GINQ can and more, but it intentionally sacrifices a familiar OO
> representation to support arbitrary intermediate data states and
> frictionless mapping-free persistence.
> >>
> >> DataFrame df = Csv.load("my.csv")
> >>    .selectColumns("id", "price")
> >>    .selectRows($decimal("price").gt(100.));
> >>
> >> Jdbc.connector(dataSource)
> >>    .tableSaver("db_table")
> >>    .save(df);
> >>
> >> Andrus
> >>
> >>
> >>> On Dec 28, 2021, at 11:50 PM, Aristedes Maniatis
> <[email protected]> wrote:
> >>>
> >>> I came across this really interesting new feature in groovy 4 today...
> >>>
> >>>            class Person {
> >>>                String name
> >>>                int age
> >>>
> >>>                Person(String name, int age) {
> >>>                    this.name = name
> >>>                    this.age = age
> >>>                }
> >>>            }
> >>>
> >>>            def persons1 = [new Person('Daniel', 35), new
> Person('Linda', 21), new Person('Peter', 30)]
> >>>            def persons2 = [new Person('Jack', 35), new Person('Rose',
> 21), new Person('Smith', 30)]
> >>>
> >>>
> >>>        def output = GQ {
> >>>                from p1 in persons1
> >>>                innerjoin p2 in persons2 on p1.age == p2.age
> >>>                select p1.name.toUpperCase(), p2.name.toUpperCase()
> >>>           }
> >>>
> >>>            assert [['DANIEL', 'JACK'], ['LINDA', 'ROSE'], ['PETER',
> 'SMITH']] == output.toList()
> >>>
> >>>
> >>> So GQ invokes this sql-like query language for Java/groovy objects.
> >>>
> >>>
> >>> Not suggesting it is useful for Cayenne, but interesting nevertheless.
> >>>
> >>>
> >>> Ari
> >>>
> >>>
> >>>
> >>>
> >>> docs:
> https://github.com/apache/groovy/blob/master/subprojects/groovy-ginq/src/spec/doc/ginq-userguide.adoc
> >>>
> >>> examples:
> https://github.com/apache/groovy/blob/master/subprojects/groovy-ginq/src/spec/test/org/apache/groovy/ginq/GinqTest.groovy
> >>>
> >>> src:
> https://github.com/apache/groovy/tree/master/subprojects/groovy-ginq/src/main/groovy/org/apache/groovy/ginq
>
>