I've got my EF Code First working exactly as expected aside from one small bit. I'm not sure how to name my Database File.
I'm using SQL CE, but I'm sure this applies to all forms of EF Code First.
Here's my DbContext
namespace MyApp.Domain.EntityFramework
{
public class DataContext : DbContext
{
//...
}
}
And when the database is created it's created as
MyApp.Domain.EntityFramework.DataContext.sdf
I'd prefer to just have it named
MyApp.sdf
Now I'm sure this is simple, but my Googling skills keep turning up examples where the database name is auto generated like mine.
http://www.hanselman.com/blog/SimpleCodeFirstWithEntityFramework4MagicUnicornFeatureCTP4.aspx
You need to specify a connection string (for example by creating a connection string named DataContext (your class name) in your config file, and set the desired name there.
I was looking to do the same. Managed to end up with this:
public class ShopDbContext : DbContext
{
public DbSet<Product> Products { get; set; }
public DbSet<Feature> Features { get; set; }
public DbSet<Category> Categories { get; set; }
public DbSet<Subcategory> Subcategories { get; set; }
public DbSet<Information> OrderInformation { get; set; }
public ShopDbContext() : base("Shop")
{
}
}
It will name your database "Shop" so just replace what is in the base("Shop") with whatever you want to call your database. Hope this helps.
Related
I have a problem. I created the following class:
public class KnownDevice
{
public int Id { get; set; }
public string Name { get; set; }
public string IP { get; set; }
public string MAC { get; set; }
public string Type { get; set; }
public List<TriangleRegistryObject> triangles { get; set; }
public List<HexagonRegistryObject> hexagons { get; set; }
}
Now, I want to create a Database on the mobile phone itself, so I use the following code to create the table:
database = DependencyService.Get<ISQLite>().GetConnection();
database.CreateTable<KnownDevice>();
But the code crashes on the second line with the error:
System.NotSupportedException: 'Don't know about
System.Collections.Generic.List`1
Now on the internet I found that it is not allowed to add a List to a database, but I need the data in that list, so I have no idea how I can fix this problem. The list can contain arround 25 rows!
Any idea how I can solve this problem?
List<TriangleRegistryObject> is not a valid type for a SQLite database value. Your type of List<TriangleRegistryObject> does not match any of the clrType == typeof(XXXX) statements, so you get that exception. You will need to rethink the class structure a little to be able to use SQLite-net like that.
For more details about the SQLite database, you could download the source file from the link for reference.
https://learn.microsoft.com/zh-cn/samples/xamarin/xamarin-forms-samples/todo/
If you want to use ou could use List, you could use SQLite-Net Extensions instead of SQLite.
You could refer to the link. The SQLite-Net Extensions library direct to specific relationships in database.
How can you store lists of objects in SQLite.net?
These are my classes:
public class Post : IPost
{
public int Id { get; set; }
public virtual int[] DuplicateOf { get; set; }
public virtual ICommentInfo[] Comments { get; set; }
}
public class CommentInfo : ICommentInfo
{
public virtual string Author { get; set; }
public virtual int Id { get; set; }
public virtual string Text { get; set; }
public virtual int PostId{ get; set; }
[ForeignKey("PostId")]
public virtual Post Post { get; set; }
}
With this CommentConfiguration added to OnModelCreate():
HasRequired(c => c.Post)
.WithMany(b=>(ICollection<CommentInfo>) b.Comments)
.HasForeignKey(b=>b.PostId)
.WillCascadeOnDelete(true);
I really cannot understand why the property Comments is always null, and why EF doesn't initialize it since it's virtual.
I tried disabling lazy loading too, but when i try loading the navigation property with context.Post.Include("Comments") an error tells me that "There is not a navigation property called Comments".
So I tried using Entity Framework Power Tools Beta 3 to see the Entity Data Model, and I discovered that there is not a navigation end for table "Post" even if there is the relationship between the two tables and there's the Comment table end too.
I sincerly don't know which way to turn, could be a problem of Array?? Should I use an Icollection property??
Though I cannot change the type of that property because Post is implementing an Interface.
Every sample I look at is clear and easy to make work. Please help me.. Thank you in advance.
EDIT:
This is what I changed after looking at the link I posted yesterday.
public class Post : IPost
{
public int Id { get; set; }
public virtual int[] DuplicateOf { get; set; }
public virtual ICollection<CommentInfo> Comments { get; set; }
ICommentInfo[] IPost.Comments {
get { return Comments ; }
set { Comments = (CommentInfo[])value; } }
}
The exception is: System.ObjectDisposedException :The ObjectContext instance has been disposed and can no longer be used for operations that require a connection and raises when the application tries to get the Comments.
If I remove the virtual key the exception disappear but the property remain always null and the values don't persist in any way.
EDITv2
I've solved my problem adding a new property and map my old property to it.
public class Post : IPost
{
public int Id { get; set; }
public virtual int[] DuplicateOf { get; set; }
public ICommentInfo[] Comments
{
get { return ListComments.ToArray(); }
}
public List<CommentInfo> ListComments {get;set;}
}
In my PostConfiguration OnModelCreate() I used the ListComments property as a navigation property like this:
HasMany(b => b.ListComments)
.WithRequired(c=>c.Post)
.HasForeignKey(c=>c.PostId)
.WillCascadeOnDelete(true);
Now it perfectly works, it was simpler than I expected and when I try to receive the Comments Collection, if I include the "ListComments" property, I get the array of Post.
Thank you for your help!
I can't access the link in your comment, but I assume you changed
public virtual ICommentInfo[] Comments { get; set; }
into the common way to define navigation properties:
public virtual ICollection<CommentInfo> Comments { get; set; }
because entity framework does not support interfaces in its conceptual model.
The exception about the disposed context means that you access this property after fetching Post objects from the database and disposing the context. This triggers lazy loading while the connection to the database is lost. The solution is to use Include:
var posts = context.Posts.Include(p => p.Comments).Where(...)
Now posts and comments are fetched in one go.
I am currently working on a Web API project with a Database-First method using Entity Framework (which I know is not the most stable of platforms yet), but I am running into something very strange.
When the GET method within my APIController tries to return all records in a DbSet with a LINQ Include() method involved such as this, it will return a 500 error:
// GET api/Casinos
public IEnumerable<casino> Getcasinos()
{
var casinos = db.casinos.Include(c => c.city).Include(c => c.state);
return casinos.AsEnumerable();
}
Yet, this method works fine, and returns my data from within my database:
// GET api/States
public IEnumerable<state> Getstates()
{
return db.states.AsEnumerable();
}
So I have proved in other instances that if it returns the entities without LINQ queries, it works great, yet when there is an Include method used upon the DbContext, it fails.
Of course, trying to find this error is impossible, even with Fiddler, Chrome/Firefox dev tools, and adding in GlobalConfiguration.Configuration.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always;
If anyone has resolved this, it would be nice to know a nice resolution so I can start returning my data! Thanks!:)
P.S. I am using SQL Server 2012
This is happening due to error in serialization (Json/XML). The problem is you are directly trying to transmit your Models over the wire. As an example, see this:
public class Casino
{
public int ID { get; set; }
public string Name { get; set; }
public virtual City City { get; set; }
}
public class State
{
public int ID { get; set; }
public string Name { get; set; }
[XmlIgnore]
[IgnoreDataMember]
public virtual ICollection<City> Cities { get; set; }
}
public class City
{
public int ID { get; set; }
public string Name { get; set; }
public virtual State State { get; set; }
[XmlIgnore]
[IgnoreDataMember]
public virtual ICollection<Casino> Casinos { get; set; }
}
public class Context : DbContext
{
public Context()
: base("Casino")
{
}
public DbSet<Casino> Casinos { get; set; }
public DbSet<State> States { get; set; }
public DbSet<City> Cities { get; set; }
}
Pay attention to the XmlIgnore and IgnoreDataMember. You need to restrict avoiding serialization so it doesn't happen in circular manner. Further, the above model will still not work because it has virtual. Remove virtual from everywhere namely City, Cities, Casinos and State and then it would work but that would be inefficient.
To sum up: Use DTOs and only send data that you really want to send instead of directly sending your models.
Hope this helps!
I had same problem in ASP.Net Core Web Api and made it working with this solution:
Add Microsoft.AspNetCore.Mvc.NewtonsoftJson nuget package to web api project.
and in Startup.cs class in ConfigureServices method add this code:
services.AddControllersWithViews().AddNewtonsoftJson(options =>
options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
);
I'm trying to get my mysql data in ASP.net MVC3.
The mysql Database Name is supply_db and table name is xcart_orders.
ASP.net code is like below,
(Im just following my book, and just switch to my DB info but it does not work :( )
(I will omit using and namespace)
Web.Config File,
<add name="EFMysqlContext" connectionString="server=XXX.XXX.XXX.XX;User Id=root;pwd=xxx;Persist Security Info=True;database=supply_db"
providerName="Mysql.Data.MySqlClient" />
Abstract/IXcartOrdersRepository.cs
public interface IXcartOrdersRepository
{
IQueryable<XcartOrder> xcart_orders { get; }
}
/Concrete/EFXcartOrderRepository.cs
public class EFXcartOrdersRepository : IXcartOrdersRepository
{
private EFMysqlContext context = new EFMysqlContext();
public IQueryable<XcartOrder> xcart_orders
{
get { return context.xcart_orders; } // I thought the 'xcart_orders' should be match with db table name, isn't it?
}
}
/Entities/XcartOrder.cs
public class XcartOrder
{
[Key]
public int orderid { get; set; }
public string login { get; set; }
public string membership { get; set; }
public decimal subtotal { get; set; }
}
and In my controller,
IXcartOrdersRepository XcartOrdersRepository = new EFXcartOrdersRepository();
int orderCnt = XcartOrdersRepository.xcart_orders.Count();
then error occur, the error message say "{"Table 'supply_db.XcartOrders' doesn't exist"}"
I think I could connect to db, but couldn't get the table.
anybody know which part do I need to change?
Thank you!
can you decorate your Xcartorder class with the Table attribute to explicitly specify the desired name?
[Table("xcart_orders")]
public class XcartOrder
{
...
edit: attribute syntax
I've just installed the new Entity Framework 4.1 NuGet package, thus replacing the EFCodeFirst package as per NuGet intructions and this article of Scott Hanselman.
Now, imagine the following model:
public class User
{
[Key]
public string UserName { get; set; }
// whatever
}
public class UserThing
{
public int ID { get; set; }
public virtual User User { get; set; }
// whatever
}
The last EFCodeFirst release generated a foreign key in the UserThing table called UserUserName.
After installing the new release and running I get the following error:
Invalid column name 'User_UserName'
Which of course means that the new release has a different FK naming strategy. This is consistent among all other tables and columns: whatever FK EFCodeFirst named AnyOldForeignKeyID EF 4.1 wants to call AnyOldForeignKey_ID (note the underscore).
I don't mind naming the FK's with an underscore, but in this case it means having to either unnecessarily throw away the database and recreate it or unnecessarily renaming al FK's.
Does any one know why the FK naming convention has changed and whether it can be configured without using the Fluent API?
Unfortunately, one of the things that didn't make it to this release is the ability to add custom conventions in Code First:
http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-release-candidate-available.aspx
If you don't want to use the fluent API to configure the column name (which I don't blame you), then most straight forward way to do it is probably using sp_rename.
Why don't you do the following?
public class User
{
[Key]
public string UserName { get; set; }
// whatever
}
public class UserThing
{
public int ID { get; set; }
public string UserUserName { get; set; }
[ForeignKey("UserUserName")]
public virtual User User { get; set; }
// whatever
}
Or, if you don't want to add the UserUserName property to UserThing, then use the fluent API, like so:
// class User same as in question
// class UserThing same as in question
public class MyContext : DbContext
{
public MyContext()
: base("MyCeDb") { }
public DbSet<User> Users { get; set; }
public DbSet<UserThing> UserThings { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<UserThing>()
.HasOptional(ut => ut.User) // See if HasRequired fits your model better
.WithMany().Map(u => u.MapKey("UserUserName"));
}
}