linq for two tables on dotvvm framework - asp.net

Question

I recently started to learn C# and DotVVM and i run to a problem. I dont know how to make linq query from two tables. I know how to make a query or linq for one table, but i got stuck with two tables.
My database of Authors
CREATE TABLE [dbo].[Autors] (
[ID] INT IDENTITY (1, 1) NOT NULL,
[Jmeno] NVARCHAR (MAX) NULL,
[Prijmeni] NVARCHAR (MAX) NULL,
[ProstredniJmeno] NVARCHAR (MAX) NULL,
[Narozeni] DATE DEFAULT (NULL) NULL,
[Umrti] DATE DEFAULT (NULL) NULL,
[Bio] NVARCHAR (MAX) NULL,
[Narodnost] NVARCHAR (MAX) NULL,
[Obrazek] NVARCHAR (MAX) NULL,
CONSTRAINT [PK_dbo.Autors] PRIMARY KEY CLUSTERED ([ID] ASC));
And my database of Books
CREATE TABLE [dbo].[Books] (
[Id] INT IDENTITY (1, 1) NOT NULL,
[Nazev] NVARCHAR (MAX) NOT NULL,
[IdAutor] INT NOT NULL,
[Popis] NVARCHAR (MAX) NULL,
[Isbn] NCHAR (15) NULL,
[IdZanr] INT NULL,
[RokVydani] INT NULL,
[PocetStran] INT NULL,
[Obrazek] TINYINT NULL,
CONSTRAINT [PK_dbo.Books] PRIMARY KEY CLUSTERED ([Id] ASC));
And i need to create linq query to get this
namespace AbsolvetnskaPrace.Models
{
public class AutorListModel
{
public int Id { get; set; }
public string Jmeno { get; set; } //First name
public string Prijmeni { get; set; } //Last name
}
}
namespace AbsolvetnskaPrace.Models
{
public class BookListModel
{
public int Id { get; set; }
public string Nazev { get; set; } //Title
public int IdAutor { get; set; }
public string JmenoAutor { get; set; } //Author's first name
public string PrijmeniAutor { get; set; } //Author's last name
}
}
i have class of Services where i have all linq queries i use. What I need is to make list of books but get a author's name and last name.
This is a view of the list:
<div class="page-center">
<div class="page-grid-top">
<div class="student-image"></div>
<h1>{{resource: Texts.Title_BookList}}</h1>
<dot:AuthenticatedView>
<dot:RouteLink Text="{resource: Texts.Label_NewBook}" RouteName="CRUD_BookCreate" class="page-button btn-add btn-long" />
</dot:AuthenticatedView>
</div>
<dot:GridView DataSource="{value: Books}" class="page-grid">
<Columns>
<dot:GridViewTextColumn ValueBinding="{value: Nazev}" HeaderText="{resource: Texts.Label_Title}" />
<dot:GridViewTextColumn ValueBinding="{value: IdAutor}" HeaderText="{resource: Texts.Label_BookAutor}" />
<dot:GridViewTemplateColumn>
<dot:RouteLink Text="{resource: Texts.Label_Detail}" RouteName="CRUD_BookDetail" Param-Id="{{value: Id}}" />
</dot:GridViewTemplateColumn>
<dot:GridViewTemplateColumn>
<dot:RouteLink Text="{resource: Texts.Label_Edit}" RouteName="CRUD_BookEdit" Param-Id="{{value: Id}}" />
</dot:GridViewTemplateColumn>
</Columns>
<EmptyDataTemplate>
{{resource: Texts.EmptyAutorTable}}
</EmptyDataTemplate>
</dot:GridView>
</div>
And finaly the result looks like this but the numbers in "Jméno a příjmení autora" shuld by Autor's first and last name. Right now the is Author's Id.
I know that this question is really long but I would be thankfull for any advice you can get me.

Answer 1

your classes (entity framework model) are missing navigation properties.
You have to add properties like this:
namespace AbsolvetnskaPrace.Models
{
public class AutorListModel
{
public int Id { get; set; }
public string Jmeno { get; set; } //First name
public string Prijmeni { get; set; } //Last name
--> pubilc ICollection<BookListModel> BookListModels { get; set; }
}
public class BookListModel
{
public int Id { get; set; }
public string Nazev { get; set; } //Titleenter code here
public int IdAutor { get; set; }
--> public AutorListModel Author { get; set; }
public string JmenoAutor { get; set; } //Author's first name
public string PrijmeniAutor { get; set; } //Author's last name
}
}
Then you linq query can look like:
context.Books.Include(a=> a.Authors).Where( -- lambda condition --).Select( -- lambda transformation --).ToList()
DotVVM serializes the objects in ViewModel, so it is highly recommended to transform you EF classes into DTO (data transfer objects) which has no logic and their main purpose is to transfer data and nothing else.