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https://issues.apache.org/jira/browse/FREEMARKER-61?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16083372#comment-16083372
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Ondra Žižka edited comment on FREEMARKER-61 at 7/12/17 3:48 AM:
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The Java method as you suggest is a good idea. I didn't think of putting the
comparator to the model. Although it's a bit more coding to add it to the model
(versus instantiating it in the template).
Edit: Now I realized Freemarker can instantiate.
{code}
<#assign comparer = objectConstructor("cz.oz.myproject.MyComparer", "foo")>
{code}
I agree that for non-java users, {{?sort_using(Comparator)}} would not be too
useful.
And as you say, it could accept a function, but that would be really crazy :) I
mean, it would do the job, but unless users desperately cry for it, I wouldn't
do that.
Originally I wanted to suggest {{?sort_by(Comparator)}} - would that be less
obtrusive? Basically no new syntax/built-in, just a support for a new parameter
type. But then I changed to {{sort_using}} because the name wouldn't match.
Now thinking about it, couldn't it be {{?sort(Comparator)}} - an optional
argument? Maybe that would be the best. Also it would be natural thing to have
- following the Java API, like, {{Collections.sort(Comparator)}}.
Also note that I would expect the comparator arguments to be template models.
Unwrapping the items beforehand, for the sake of optimization, could be
optional, false by default (following the less surprise rule of thumb).
Together with the instantiation above, that would be exactly what I long for:
{code}
<#assign comparator = objectConstructor("cz.oz.myproject.MyComparator", "foo")>
<#list reportModel.relatedResources.applications.list)?sort(comparator, true)
as applicationReport>
{code}
That would be wonderful!
was (Author: pekarna):
The Java method as you suggest is a good idea. I didn't think of putting the
comparator to the model. Although it's a bit more overhead of adding it to the
model (versus instantiating it).
Edit: Now I realized Freemarker can instantiate.
{code}
<#assign comparer = objectConstructor("cz.oz.myproject.MyComparer", "foo")>
{code}
I agree that for non-java users, {{?sort_using(Comparator)}} would not be too
useful.
And as you say, it could accept a function, but that would be really crazy :) I
mean, it would do the job, but unless users desperately cry for it, I wouldn't
do that.
Originally I wanted to suggest {{?sort_by(Comparator)}} - would that be less
obtrusive? Basically no new syntax/built-in, just a support for a new parameter
type. But then I changed to {{sort_using}} because the name wouldn't match.
Now thinking about it, couldn't it be {{?sort(Comparator)}} - an optional
argument? Maybe that would be the best. Also it would be natural thing to have
- following the Java API, like, {{Collections.sort(Comparator)}}.
Also note that I would expect the comparator arguments to be template models.
Unwrapping the items beforehand, for the sake of optimization, could be
optional, false by default (following the less surprise rule of thumb).
Together with the instantiation above, that would be exactly what I long for:
{code}
<#assign comparator = objectConstructor("cz.oz.myproject.MyComparator", "foo")>
<#list reportModel.relatedResources.applications.list)?sort(comparator, true)
as applicationReport>
{code}
That would be wonderful!
> ?sort_using with a Comparator parameter
> ---------------------------------------
>
> Key: FREEMARKER-61
> URL: https://issues.apache.org/jira/browse/FREEMARKER-61
> Project: Apache Freemarker
> Issue Type: New Feature
> Components: engine
> Affects Versions: 2.3.26-incubating
> Reporter: Ondra Žižka
>
> Hi Daniel :)
> I know that lists should be sorted before passing them to the template in
> general.
> In our case, the template is backed by a generic API for graph database which
> gives an {{Iterable}} for any 1:N relation. So sorting needs to happen in the
> template.
> Now I'd like to sort that, for which the {{?sort_by(["...", "..."])}} is good
> enough, except when it gets a bit more complicated - e.g. sometimes the
> values are missing in which case it should sort by something else...
> Doing that in a template is not a good idea, so I suggest this, elegant in my
> opinion, solution:
> First you'd have a Comparator in Java, and perhaps register it like you do
> with {{FreemarkerMethod}}.
> Then you could pass this as a parameter to {{?sort_using.}}
> {code}
> public class SortByName implements Comparator { ... }
> myData.persons?sort_using("SortByName")
> {code}
> This would be even better if it could pass parameters to the constructor:
> {code}
> public class SortByName implements Comparator {
> public SortByName(boolean ladiesFirst) { ... }
> }
> myData.persons?sort_using("SortByName", [true])
> {code}
> This would greatly leverage sorting in templates while not complicating the
> template syntax or cluttering {{?sort_by}}.
> Thanks for considering.
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