Automapper: OrderByDescending Child Collection with ProjectTo<DTO>

[lixaotec]

Dear folks,

Is it possible to OrderByDescending a child collection property in a projection with ProjectTo?

EF Core 3 seems to accomplish when i project on hand like q=>new { collection.Select(... OrderByDescending) however I wish not to project by hand. Wish to use a single ProjectTo that does the job.

Appreciate any help or path

Thanks

[lbargaoanu]

You need to write the OrderBy in your map configuration. If you need help on how to do that, try SO.

[lixaotec]

Dear @lbargaoanu .

Appreciate your help.
Ive read about this possibility on docs. However i was hoping to have another way.

I take the opportunity to ask regarding a feature, as Iam essencially using ProjectTo() with my Dtos. And they all are mapped through Attributes (really enjoy that feature). So i was wondering have such feature to create this mapping configuration just in use or ProjectTo

Would be something like

query.Skip().Take()
.ProjectTo(_mapper...)
.FromMember(....)// as in docs for supperseed expression rules like my needs of order by
.ToList()

Would you accept such ideia of improvement?

( that would help on keep things better placed , other than have map configs in a separeted file. I saw a PR with somethiing with ctors, couldnt understand if is it something lile this)

[lbargaoanu]

It doesn't seem general enough. I don't think we would accept a PR with such a feature. You could try to configure the order per call by passing parameters and using them in your mapping.

[lbargaoanu]

Another option is to try to apply the order in your source query, before the projection.

[lixaotec]

The order works for first level properties, but not for child collections as initial question, without mapping configuration apart.

What do you mean by passing parameters? Couldn’t figure out

[lbargaoanu]

http://docs.automapper.org/en/latest/Queryable-Extensions.html#parameterization
I think this is better suited for StackOverflow.

[lock[bot]]

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