Using DataSourceLoader with custom sort

[MihaMarkic]

For various reasons, I want to pass an IQueryable containing an OrderBy statement to DataSourceLoader.Load.

Basicallly something like

var items = db.Items.OrderBy(i => i.Name).Select(i => i.Name);

 // where loadOptions.Sort = new SortingInfo[0];
var result = DataSourceLoader.Load(items, loadOptions);

When working with version 2.4.4 Load did honor the OrderBy, but 2.5.0 ignores it completely (both ignore it actually). So, how I go with custom sorting in this case?

[AlekseyMartynov]

You can use the DataSourceLoadOptionsBase.DefaultSort property or build a custom sort list:

var mySort = . . .;
loadOptions.Sort = mySort; 

The following support ticket may be relevant:

• https://devexpress.com/issue=T657002

[MihaMarkic]

@AlekseyMartynov Well, that most probably won't work if I were to use a client side projection.

[AlekseyMartynov]

Would you please add a code sample to illustrate what exactly won't work?

Internally, DataSourceLoader builds a LINQ expression by appending Where, OrderBy, etc to the source query. For example:

db.Items.OrderBy(i => i.Name).Select(i => i.Name)
    .Where(...)
    .OrderBy(...)

Subsequent OrderBy cancels previous OrderBy. To keep sorting by Name, you can use DefaultSort or modify Sort as suggested in #388 (comment).

Alternatively, we can add a boolean option to prevent any sort inside DataSourceLoader when the source query is pre-sorted.

[MihaMarkic]

@AlekseyMartynov Sorry for the delay

Imagine a projection to a

class ClientSide {
  public string LowercaseName { get; set; }
}

DataSourceLoader.Load(db.Items.Select(i => new ClientSide { LowercaseName = string.ToLower(i.Name) } , loadOptions});

Perhaps I'm wrong, but Select in this case is client side and applying sort and/or filter on it, would cause a problem because it will have to fetch all the data from the database first.

[AlekseyMartynov]

Thank you for the update. Now I better understand the issue. You need to sort original items by Name and then project them so that Name becomes LowercaseName.

I just posted a comment about DTO mapping. Please review it and let me know if such a feature would address your requirements. In the interim, check if you can use the workaround suggested in #378 (comment).