MySQL Connector/NET and Entity Framework

How to let MySQL Connector/NET and Entity Framework play nicely. This blog post is a quicky and an oldy… Since we still receive a reasonable amount of questions about this topic at the customer service of my employer I’m posting this here, with some commonly made mistakes and points of attention.

MySQL Connector/NET version 6.6.4.0

Basically, it all comes down to your web.config configuration if you want to use MySQL Connector/NET and Entity Framework. You can use the website configuration from my article “MySQL Connector/NET 6.5 in partial trust” to set up MySQL Connector/NET for your website application. There are a few other settings you need to look at:

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About Entity Framework

Entity Framework (EF) is an object-relational mapper that enables .NET developers to work with relational data using domain-specific objects. It eliminates the need for most of the data-access code that developers usually need to write.

Visual Studio 2008: incorrect connection string

Visual Studio 2008 used to generate an incorrect connection string where it uses ” marks instead of ‘. I can’t imagine this hasn’t been fixed 😉 but do check it in your web.config file if you encounter error message with MySQL Connector/NET and Entity Framework.

Incorrect generated connection string

<add name="modelEntities" connectionString="metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl;
  provider=MySql.Data.MySqlClient;
  provider connection string="server=mysql.server.ext;
    User Id=mysqluser;
    Persist Security Info=True;
    database=mysqldb;
    password=mysqlpwd""
  providerName="System.Data.EntityClient"
/>

Correct connection string

<add name="modelEntities" connectionString="metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl;
  provider=MySql.Data.MySqlClient;
  provider connection string='server=mysql.server.ext;
    User Id=mysqluser;
    Persist Security Info=True;
    database=mysqldb;
    password=mysqlpwd'"
  providerName="System.Data.EntityClient"
/>

DbProviderFactories

You also have to verify you are using the correct version of assemblies. Therefor it’s wise to add a DbProviderFactories-section to your web.config, to make sure you are loading the assemblies in your ~/bin folder.

<system.data> 
  <DbProviderFactories> 
    <add name="MySQL Data Provider"
      invariant="MySql.Data.MySqlClient"
      description=".Net Framework Data Provider for MySQL"
      type="MySql.Data.MySqlClient.MySqlClientFactory,
        MySql.Data, Version=6.6.4.0,
        Culture=neutral,
        PublicKeyToken=c5687fc88969c44d"
    /> 
  </DbProviderFactories> 
</system.data>

ASP.NET 4.0, MVC 3 en Entity Framework Code First

For EntityFramework 4.3.1.0 en trustLevel=”medium”, add requirePermission=”false” to the entityFramework node of your web.config file:

<configSections>
<!--
[...]
-->
  <section name="entityFramework"
    type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection,
    EntityFramework, Version=4.3.1.0, Culture=neutral, 
    PublicKeyToken=b77a5c561934e089" requirePermission="false" />

<!--
[...]
-->
</configSections>

Source: ScottGu: Code-First Development with Entity Framework 4

Hint: MySQL table engine

To use full power of Entity Framework, use the InnoDB table engine because it supports foreign keys. Learn how to convert MyISAM tables to InnoDB.