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POHow to use Database Migrations and EF 4.3 with a code first approach to create relationship tables?
 

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  1. POHow to use Database Migrations and EF 4.3 with a code first approach to create relationship tables?
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    <p>I have been trying to get a handle on using MVC 4.0 with EF 4.3 and Database Migrations as introduced by Scott Gu at Tech Days and have run into an issue with the database that is created when a many to many relationship exists.</p> <p><a href="http://channel9.msdn.com/Events/TechDays/Techdays-2012-the-Netherlands/2364" rel="nofollow">http://channel9.msdn.com/Events/TechDays/Techdays-2012-the-Netherlands/2364</a> starts at 21:14</p> <p>Included are the snippets of code that were used to generate the database as shown in the image below.</p> <pre><code>public class Trip { public int ID { get; set; } public string Name { get; set; } public DateTime Begin { get; set; } public DateTime End { get; set; } public Location HomeCountry { get; set; } //public IList&lt;Location&gt; Itinerary { get; set; } public ICollection&lt;Location&gt; Itinerary { get; set; } public Trip() { this.Itinerary = new HashSet&lt;Location&gt;(); } } public class Location { public int ID { get; set; } public string Name { get; set; } public ICollection&lt;Trip&gt; Trips { get; set; } public Location() { this.Trips = new HashSet&lt;Trip&gt;(); } } </code></pre> <p>This was the resulting database. (I would have posted an image, but I am unable to post an image, still being a new user)</p> <pre> Tables Locations PK ID (int) Name (varchar) Trip_ID (int) Trips PK ID (int) Name (varchar) Begin (datetime) End (datetime) HomeCountry_ID (int) </pre> <p>I guess I would have expected a third relationship table to be created for the many to many relationship between Locations and Trips (many Locations can apply to many Trips), versus, adding the Trip_Id column to the Locations table. Does anyone know what I did wrong here? Is there a way to get the data base automation to create these tables correctly?</p> <p>Thanks in advance for all of your help!</p> <p><b>Update:</b> I found the following link, but I am still unable to get this to work using EF 4.3. I also edited my code snippets to reflect the following post. </p> <p><a href="http://www.codeproject.com/Articles/234606/Creating-a-Many-To-Many-Mapping-Using-Code-First" rel="nofollow">http://www.codeproject.com/Articles/234606/Creating-a-Many-To-Many-Mapping-Using-Code-First</a></p>
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      1. POHow to use Database Migrations and EF 4.3 with a code first approach to create relationship tables?
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    1. CODid you use the fluent api or what for creating the relationship? I need to see that.
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      1. USJohn Kalberer
    2. CO@John Currently I am working on this solely to get a grasp of the presentation that I watched and get an understanding of how useful this could be for simple projects. I was using the built in functionality within Visual Studio to build your models and then create the db around them. When creating a controller, I am able to select the Data Context and it creates the entity framework class for me as well as the files to create it. In the Nuget console, I am able to use the Add-Migration and Update-Database commands to create the database and any changes along the way.
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