带有实体框架 6 的 SQLite“没有这样的表”

Question

I'm trying to implement this question with SQLite and EntityFramework 6 code first. I can create the database and there is a file (although empty), but when I try to add an entry to the database it says there is no such table. Yet, when I try to create the table manually ( db.Database.ExecuteSqlCommand("CREATE TABLE etc.) ) it tells me that the table already exists.

I found some questions about this already, but they're all about the path not being absolute, which is simply not the case here.

Context

//Context:
class MediaContext : DbContext
{
    public DbSet<MediaModel> Media { get; set; }

    public MediaContext(string filename): base(new SQLiteConnection() {
        ConnectionString =
            new SQLiteConnectionStringBuilder()
            { DataSource = filename, ForeignKeys = false }
            .ConnectionString
    }, true)
    {

    }        
}

DAL

//In the DAL:
public DataAccessLayer(string path)
{
   _path = Path.GetFullPath(path); //<--The path already comes full in, I'm just paranoid at this point.
   _connectionPath = _path + @"\MyDatabase.sqlite";

   using (var db = new MediaContext(_connectionPath))
   {
      db.Database.CreateIfNotExists();
      db.Database.Initialize(false);                

       db.SaveChanges();
   }

   public void Generate()
   {
       using (var db = new MediaContext(_connectionPath))
       {
          db.Media.Add(new MediaModel("test"));
          db.SaveChanges(); //<--SQLiteException: SQL logic error or missing database: no such table: MediaModels

        }
    }

App.Config

//App.config:
<configuration>
  <configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
  </configSections>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
  </startup>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v13.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
      <remove invariant="System.Data.SQLite.EF6" />
      <add name="SQLite Data Provider (Entity Framework 6)" invariant="System.Data.SQLite.EF6" description=".NET Framework Data Provider for SQLite (Entity Framework 6)" type="System.Data.SQLite.EF6.SQLiteProviderFactory, System.Data.SQLite.EF6" />
      <remove invariant="System.Data.SQLite.EF6" />
      <add name="SQLite Data Provider" invariant="System.Data.SQLite.EF6" description=".NET Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" />
    </DbProviderFactories>
  </system.data>
</configuration>

Answer 1

I have got Code First approach working inspired by this post:
Create SQLite DB using Entity Framework Core Code First

The trick is to have a call to EnsureCreated in the context constructor:

    public MediaContext()
    {
        Database.EnsureCreated();
    }

---

Regarding the table name to property name matching:
You can use the Table attribute to make things work:

public DbSet<MediaModel> Media { get; set; }

and explicitly specify the table name in your model class although this seems redundant:

[Table("MediaModel")]
public class MediaModel

Answer 2

EF6 的 SQLite 提供程序不支持 Code First/Migrations 工作流，因此您必须在 EF6 工作流之外手动创建数据库。

Answer 3

This is the recommended reply from Microsoft itself :

Visual Studio uses an inconsistent working directory when running .NET Core console apps. (see dotnet/project-system#3619) This results in an exception being thrown: no such table: Blogs. To update the working directory:

Right-click on the project and select Edit Project File

Just below the TargetFramework property, add the following:

<StartWorkingDirectory>$(MSBuildProjectDirectory)</StartWorkingDirectory>

Save the file

Now you can run the app:

Debug > Start Without Debugging

Answer 4

Like ErikEJ said does SQLite not support code first in they way I use it, and apparently it has a strict naming policy.

To make it all work I had to manually create the table, and adapt the context to the naming schema ( Media => MediaModels ).

Context

public DbSet<MediaModel> MediaModels { get; set; }

DAL

public DataAccessLayer(string path)
{
    _path = Path.GetFullPath(path);
    _connectionPath = _path + @"\MyDatabase.sqlite";
    
    using (var db = new MediaContext(_connectionPath))
    {
        db.Database.ExecuteSqlCommand("CREATE TABLE IF NOT EXISTS 'MediaModels' ('Name' TEXT, 'FilePath' TEXT NOT NULL PRIMARY KEY, 'Tags' TEXT, 'Note' TEXT, 'FileExtension' TEXT)");

        db.SaveChanges();
    }
}
    
public void Generate()
{
    using (var db = new MediaContext(_connectionPath))
    {
        db.MediaModels.Add(new MediaModel("test"));
        db.SaveChanges();
    }
}

That code is still not perfect, and I'll try to update this answer as I improve it.

Answer 5

I'm using .NET Core and EntityFramework Core 2 and code first migration for SQLite. Specifying table name in OnModelCreating helped to solve the issue:

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<File>()
            .ToTable(typeof(File).Name + "s") // <-- the argument could be just "Files"
            .HasKey(lf => new { lf.MachineName, lf.PathName });

        base.OnModelCreating(modelBuilder);
    }

Another option - TableAttribute also should have helped:

    [Table("Files")]
    public class File
    {
        // ...
    }

OnModelCreating will override table name specified in TableAttribute if both are specified.