没有App.config的SQLite实体框架

Question

It is necessary to use the SQLite Entity Framework Database-first approach for the 3d-party application plugin. I searched all the Internet, including Add a DbProviderFactory without an App.Config , Problems using Entity Framework 6 and SQLite and many other. I have tried to use them all in different ways and combinations, but nothing helps:

"An unhandled exception of type 'System.Data.Entity.Core.MetadataException' occurred in mscorlib.dll. Additional information: Schema specified is not valid. Errors: AutosuggestModel.ssdl (2,2): error 0152: No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SQLite.EF6'. Make sure the provider is registered in the 'entityFramework' section of the application config file."

There is a test console application in the solution. With this minimal App.config it works:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <entityFramework>
    <providers>
      <provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
      <add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".NET Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" />
    </DbProviderFactories>
  </system.data>
</configuration>

The connection string has already implemented in the code. Used packages are:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="EntityFramework" version="6.1.3" targetFramework="net452" />
  <package id="System.Data.SQLite" version="1.0.98.1" targetFramework="net452" />
  <package id="System.Data.SQLite.Core" version="1.0.98.1" targetFramework="net452" />
  <package id="System.Data.SQLite.EF6" version="1.0.98.1" targetFramework="net452" />
  <package id="System.Data.SQLite.Linq" version="1.0.98.1" targetFramework="net452" />
</packages>

Please, give all the required code and specify where to insert it. Thanks in advance.

Answer 1

Here is a sample code that illustrates how to achieve the goal.

namespace SqliteEFNoConfig
{
    using System.Configuration;
    using System.Data;
    using System.Data.Common;
    using System.Data.Entity;
    using System.Data.Entity.Core.Common;
    using System.Data.SQLite;
    using System.Data.SQLite.EF6;
    using System.Linq;

    internal class Program
    {
        private static void Main()
        {
            // EF manages the connection via the DbContext instantiation
            // connection string is set in config
            // Use this code if you want to use a config file
            // with only the connection string
            //using (var model = new Model1())
            //{
            //    var dbSetProperty = model.dbSetProperty.ToList();
            //}

            // Alternative method: 
            // Use this code if you don't want to use a config file
            // You will also need to use the override constructor shown below,
            // in your EF Model class
            var connectionString = @"data source = {PathToSqliteDB}";
            using (var connection = new SQLiteConnection(connectionString))
            {
                using (var model = new Model1(connection))
                {
                    var dbSetProperty = model.dbSetProperty.ToList();
                }
            }
        }
    }

    class SqliteDbConfiguration : DbConfiguration
    {
        public SqliteDbConfiguration()
        {
            string assemblyName = typeof (SQLiteProviderFactory).Assembly.GetName().Name;

            RegisterDbProviderFactories(assemblyName );
            SetProviderFactory(assemblyName, SQLiteFactory.Instance);
            SetProviderFactory(assemblyName, SQLiteProviderFactory.Instance);
            SetProviderServices(assemblyName,
                (DbProviderServices) SQLiteProviderFactory.Instance.GetService(
                    typeof (DbProviderServices)));
        }

        static void RegisterDbProviderFactories(string assemblyName)
        {
            var dataSet = ConfigurationManager.GetSection("system.data") as DataSet;
            if (dataSet != null)
            {
                var dbProviderFactoriesDataTable = dataSet.Tables.OfType<DataTable>()
                    .First(x => x.TableName == typeof (DbProviderFactories).Name);

                var dataRow = dbProviderFactoriesDataTable.Rows.OfType<DataRow>()
                    .FirstOrDefault(x => x.ItemArray[2].ToString() == assemblyName);

                if (dataRow != null)
                    dbProviderFactoriesDataTable.Rows.Remove(dataRow);

                dbProviderFactoriesDataTable.Rows.Add(
                    "SQLite Data Provider (Entity Framework 6)",
                    ".NET Framework Data Provider for SQLite (Entity Framework 6)",
                    assemblyName,
                    typeof (SQLiteProviderFactory).AssemblyQualifiedName
                    );
            }
        }
    }
}

In case you decide to not add a connection string in the config file then you need to add the following constructor in the EF model.

public Model1(DbConnection connection)
    : base(connection, true)
{
}

Notice: The above code is just a sample on how to achieve the goal and you will have to adjust it accordingly to your needs. The above code is provided assuming you are using EF Code First approach.