Implement an Entity Query Builder
---------------------------------
Key: OFBIZ-4053
URL: https://issues.apache.org/jira/browse/OFBIZ-4053
Project: OFBiz
Issue Type: New Feature
Components: framework
Affects Versions: SVN trunk
Reporter: Scott Gray
Assignee: Scott Gray
As discussed on the dev list here:
http://ofbiz.markmail.org/thread/l6kiywqzfj656dhc
Attached is an initial implementation of builder classes (of sorts) that make
use of method chaining in order to simplify use of the Delegator interface to
query entities.
Rather than taking all possible query parameters into a single method as the
delegator does, this implementation instead builds a query through a succession
of distinct method calls.
A simple example:
{code}
// Using the Delegator interface directly
eli = delegator.find("FinAccountTrans", condition, null, null,
UtilMisc.toList("-transactionDate"), null);
// Using the new implementation
eli =
EntityBuilderUtil.list(delegator).from("FinAccountTrans").where(condition).orderBy("-transactionDate").iterator();
{code}
A more complex example:
{code}
// Delegator
EntityCondition queryConditionsList =
EntityCondition.makeCondition(allConditions, EntityOperator.AND);
EntityFindOptions options = new EntityFindOptions(true,
EntityFindOptions.TYPE_SCROLL_INSENSITIVE, EntityFindOptions.CONCUR_READ_ONLY,
true);
options.setMaxRows(viewSize * (viewIndex + 1));
EntityListIterator iterator = delegator.find("OrderHeader",
queryConditionsList, null, null, UtilMisc.toList("orderDate DESC"), options);
// becomes
EntityListIterator iterator = EntityBuilderUtil.list(delegator).distinct()
.from("OrderHeader")
.where(allConditions)
.orderBy("orderDate DESC")
.maxRows(viewSize * (viewIndex + 1))
.cursorScrollInsensitive()
.iterator();
{code}
A couple of issues with the implementation so far that I'm not entirely happy
with:
- I'm not so sure that I like EntityBuilderUtil.list(delegator) in place of
something like EntityList.use(delegator). The latter requires less typing and
I think is more intuitive than typing EntityBuilderUtil because of its
similarities to the corresponding minilang method calls, I actually kept having
trouble remembering what it was called when converting some delegator calls
over. It also requires a little more typing (16-17 characters vs. 12-13), not
a big deal but every little bit helps with what would be a very commonly used
class.
- I'm struggling to see the point of having the GenericQueryBuilder interface,
the two classes share very little in the way of API and its use seems a little
superfluous to me.
Opinions on the above points or anything else to do with the implementation are
most welcome. I'd like to get the API locked down (and hopefully some javadocs
in place) before committing.
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