On Apr 16, 2012, at 11:11 PM, Vincent Massol wrote:
>
> On Apr 16, 2012, at 10:23 PM, Jerome Velociter wrote:
>
>> On Mon, Apr 16, 2012 at 9:59 PM, Vincent Massol <[email protected]> wrote:
>>> Hi,
>>>
>>> On Apr 16, 2012, at 8:10 PM, Jean-Vincent Drean wrote:
>>>
>>>> Hi devs,
>>>>
>>>> while replacing calls to xwiki#searchDocuments by calls to the query
>>>> manager script service I ran into the following query manager issue:
>>>> http://jira.xwiki.org/browse/XWIKI-7273 (XWQL short form queries
>>>> should distinct on document fullname.)
>>>>
>>>> I think we could use the recent QueryFilter mechanism to handle the
>>>> addition of the "distinct" in the select statement.
>>>> https://github.com/xwiki/xwiki-platform/blob/master/xwiki-platform-core/xwiki-platform-query/xwiki-platform-query-manager/src/main/java/org/xwiki/query/QueryFilter.java
>>>>
>>>> QueryFilters allow to:
>>>> - transform queries depending on a dynamic parameter (for example the
>>>> user preferences in HiddenDocumentFilter)
>>>> - transform the select part of a short query, without requiring
>>>> programming rights
>>>>
>>>> Here's an example of what it could look like from a velocity script:
>>>> ----------------------------------------------------8<----------------------------------------------------
>>>> #set($query =
>>>> $services.query.xwql("").addFilter("unique").addFilter("hidden"))
>>>> ----------------------------------------------------8<----------------------------------------------------
>>>> Note that in the future we could decide that the Query wrapper we use
>>>> in the QueryManagerScriptService (ScriptQuery) have the "unique"
>>>> filter by default + a way to remove it from the script.
>>>>
>>>> I wasn't expecting us to consider using multiple filters when I added
>>>> the new APIs in Query (4.0RC1).
>>>> If we agree that a QueryFilter would be a nice way to handle this, I'd
>>>> like to break those API before we release 4.0:
>>>> ----------------------------------------------------8<----------------------------------------------------
>>>> - Query setFilter(QueryFilter filter);
>>>> + Query addFilter(QueryFilter filter);
>>>> - QueryFilter getFilter();
>>>> + List<QueryFilter> getFilters();
>>>> ----------------------------------------------------8<----------------------------------------------------
>>>
>>> It's a little bit more complex. We did consider several filters when we
>>> added setFilter()!! :)
>>>
>>> We said that if we need more than one filter we could have an AndFilter()
>>> that takes a list of Filters. And allow more complex filters should we need
>>> them, like OrFilter, etc.
>>>
>>> #set($query = $services.query.xwql("").setFilter(new AndFilter("unique",
>>> "hidden"))
>>>
>>> Written with a fluent API that would give:
>>>
>>> #set($query = $services.query.xwql("").setFilter(and("unique", "hidden"))
>>>
>>> Or even:
>>>
>>> #set($query = $services.query.xwql("").setFilter("unique").and("hidden")
>>>
>>> Anyway I'm just mentioning this to explain what we thought about and an
>>> alternative to addFilter(). The only problem with addFilter() is if you
>>> need more complex Filters later on. It's not extensible whereas using
>>> AndFilter() and OrFilter() is more extensible at the expense of a little
>>> bit more text if not using a fluent api.
>>
>> Also you can't expose it that easily in velocity. For example your
>> fluent APIs examples above won't work in velocity ; you would need a
>> layer in between to adapt from script service APIs to the Java APIs.
>
> You can't do a "new" but the point of the fluent API is to not have to write
> any "new" (to make it fluent) and thus it's well adapted to Velocity actually
> :)
>
> BTW on http://en.wikipedia.org/wiki/Fluent_interface#Java their examples
> shows a usage where they call setParameter several times.
>
> This is also a possibility. We can call setFilter() several times.
BTW another possibility is:
...setFilter("unique").and().setFilter("hidden")
I had found a nice blog post on how to implement chaining like this with an
order but I cannot find it again.
Thanks
-Vincent
> Thanks
> -Vincent
>
>> Jerome.
>>
>>>
>>> Anyway I'm fine with either addFilter or setFilter.
>>>
>>> Also +1 to use a QueryFilter for adding a "distinct" in the query.
>>>
>>> Thanks
>>> -Vincent
>>>
>>>> WDYT ?
>>>> JV.
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