Using DataSourceLoader with custom sort #388

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1. AlekseyMartynov

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   on Oct 1, 2019
2. AlekseyMartynov commented on Oct 1, 2019

   

   AlekseyMartynov

   on Oct 1, 2019

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   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
3. MihaMarkic commented on Oct 2, 2019

   

   MihaMarkic

   on Oct 2, 2019

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   @AlekseyMartynov Well, that most probably won't work if I were to use a client side projection.
4. AlekseyMartynov commented on Oct 2, 2019

   

   AlekseyMartynov

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   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.
5. AlekseyMartynov

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   on Oct 18, 2019
6. AlekseyMartynov

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7. MihaMarkic commented on Oct 18, 2019

   

   MihaMarkic

   on Oct 18, 2019

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   @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.
8. AlekseyMartynov commented on Oct 18, 2019

   

   AlekseyMartynov

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   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).
9. AlekseyMartynov

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   on Oct 18, 2019