The first step in this direction is committed under CAY-1960. Now you can do
this (with or without a static import) :
import static org.apache.cayenne.exp.ExpressionFactory.*;
and(E1.P1.eq("a"), E1.P2.ge(5), E1.P3.le(77));
or(E1.P1.eq("a"), E1.P2.ge(5));
// new positional binding
exp("a = $a and b = $b", "param1", "param2");
// equivalent name binding
exp("a = $a and b = $b").params(new HashMap() {{
put("a", "param1");
put("b", "param2");
}});
Creation of expressions from Strings and binding parameters to them is now made
much easier.
Andrus
On Oct 11, 2014, at 4:06 AM, Andrus Adamchik <[email protected]> wrote:
> I think this was a very productive discussion. Based on it and some more
> thinking, here is my takeaway:
>
> 1. Instead of drastically redoing good old SelectQuery, we'll create a
> separate class called ObjectSelect featuring fluent API. No deprecations in
> SelectQuery. In fact the existing API still appears to be very useful in
> dynamic query configuration scenarios. I encounter them rather often in
> framework'y code where the decisions need to be made based on preconfigured
> variables:
>
> 1a. if(cachePolicy == LOCAL_CACHE) {
> query.useLocalCache();
> }
>
> vs.
>
> query.setCachePolicy(cachePolicy);
>
> 1b. SelectQuery<?> q;
> if(fetchDataRows) {
> q = SelectQuery.dataRowsQuery(type);
> }
> else {
> q = SelectQuery.query(type);
> }
>
> vs.
>
> SelectQuery q = new SelectQuery(type);
> q.setFetchingDataRows(fetchDataRows);
>
> Also cases when you need to reset/replace previous settings. So both styles
> have their use.
>
> 2. Instead of "qualifier" the new query might just use "exp" (in addition to
> "and" and "or").
>
> 3. ExpressionFactory.exp(..) and ObjectSelect.exp(..) should allow for both
> named parameter binding as well as vararg positional binding.
>
> 4. Still need to come up with fluent API for orderings and prefetches.
> Separation from SelectQuery should simplify this task.
>
> 5. The last method in a chain doesn't have to be limited to "select" and
> "selectOne". It can be query-specific, depending on what operations a given
> query supports. E.g. we can have queries with "count(context)", etc. This is
> something we should explore.
>
> 6. Corollary to #5, we should explore iterator methods in query chains (need
> to make sure that we don't reinvent the wheels invented in Java 8).
>
> 7. Non-selecting queries should use such API too. E.g. in addition to
> SQLSelect we might have SQLOperation with chain terminating with "int
> update(context)" or "int[] batchUpdate(context)" or "QueryResponse
> exec(context)". Same goes for ProcedureQuery.
>
> Andrus
>
> On Oct 5, 2014, at 11:10 AM, Andrus Adamchik <[email protected]> wrote:
>
>> In preparation to 3.2.M2, I am working on polishing our new query APIs. Good
>> examples of the new API are a new SelectById query [1] and of course
>> previously available SQLSelect. Now started working on SelectQuery, which is
>> a more subtle matter as it affects every single Cayenne user. So instead of
>> committing it right away, I created a pull request #16 [2] and now would
>> like to hear comments before this goes to the main repo.
>>
>> This changes SelectQuery and tweaks ExpressionFactory and Expression. You
>> get the most milage out of it if you statically import ExpressionFactory. A
>> good example is the Main file from our tutorials [3]:
>>
>> // static imports
>> import static org.apache.cayenne.exp.ExpressionFactory.exp;
>> import static org.apache.cayenne.exp.ExpressionFactory.or;
>> ...
>>
>> // a single chain from query to object list
>> List<Painting> paintings2 = SelectQuery.query(Painting.class,
>> qualifier2).select(context);
>> ...
>>
>> // static use of "exp" (former "Expression.fromString")
>> // immediate parameter binding
>> Expression qualifier3 = exp("artist.dateOfBirth < $date", "date",
>> c.getTime());
>>
>> // static use of 'or' seems cleaner than chaining expressions with
>> 'exp.orExp(..)'
>> List<Painting> paintings4 = SelectQuery.query(Painting.class, or(qualifier2,
>> qualifier3)).select(context);
>>
>> Comments?
>>
>> Andrus
>>
>> [1]
>> https://github.com/apache/cayenne/blob/master/cayenne-server/src/main/java/org/apache/cayenne/query/SelectById.java
>> [2] https://github.com/apache/cayenne/pull/16
>> [3]
>> https://github.com/andrus/cayenne/blob/9dca05242d393aba5892b6ce33e36fc7e2078bca/tutorials/tutorial/src/main/java/org/apache/cayenne/tutorial/Main.java
>
>
