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c#linqdevexpressxpo

How to set up persistent object for one-to-many and many-to-many at same time? [DevExpress]

I have an issue with next scheme, I attached it.I want to query from my database with only one object with "Manufacturer" class. Like:

var res = new XPQuery<Manufacturer>(session);

And then query all info that are related to my condition in LINQ. I have tried XPLiteObject, XPObject, Association attribute, NoForeignKey Attribute, XPOCollection and a lot of stuff but nothing didn't help me.

I have tried a lot of approaches and every time I have new exception like: SelectMany - method is not supported. Can't set foreign key in table. Duplicate primary key.

My question is: how to describe classes for normal extraction data from db? TableScheme

UPD: My solution now is: to use .ToList() at every object and then use linq-query for join data and make needed query.

var manufacturer = new XPQuery<Manufacturer>(session).ToList();
var cars = new XPQuery<Car>(session).ToList();
var countries = new XPQuery<Country>(session).ToList();

var result = from m in manufacturer ....
Solution

  • So, I have found a solution to my question. I downloaded DevExpress that can add templates for visual studio. Then I select Add new item to my project named "DevExpress ORM DataModel Wizard". This wizard can create persistent objects for existing database. After that I can query database with next syntax:

    var manufacturer = new XPQuery<Manufacturer>(session).Select(x => x....)...;

    But if you want to use .SelectMany() in your LINQ query you should use .ToList() and then use .SelectMany(). I faced with a lot of issues when I have tried to join or perform some other LINQ related operations. Well, if you got some errors, firstly after .Select() try .ToList() and then perform your operation.