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POEF4 Mapping one-to-many on existing database without navigation
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  1. POEF4 Mapping one-to-many on existing database without navigation
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    copied!<p>I'm using ModelBuilder to map an existing database to POCOs. I have courses, students, and meetings. Here are the tables</p> <pre><code>CREATE TABLE Courses ( CourseID int, Name string) CREATE TABLE Students( StudentID int, Name string) CREATE TABLE Courses_Students ( CourseID int, StudentID int) CREATE TABLE Meetings ( MeetingID int, CourseID int, MeetDate datetime) </code></pre> <p>And the POCOs</p> <pre><code>public class Course { public int CourseID { get; set; } public string Name { get; set; } public virtual ICollection&lt;CourseMeeting&gt; Meetings { get; set; } public virtual ICollection&lt;Student&gt; Students { get; set; } } public class Student { public int StudentID { get; set; } public string Name { get; set; } } public class Meeting { public int MeetingID { get; set; } public int CourseID { get; set; } public DateTime MeetDate { get; set; } } </code></pre> <p>The table mapping works great:</p> <pre><code>modelBuilder.Entity&lt;Course&gt;().MapSingleType().ToTable("Courses"); modelBuilder.Entity&lt;Student&gt;().MapSingleType().ToTable("Students"); modelBuilder.Entity&lt;Meeting&gt;().MapSingleType().ToTable("Meetings"); </code></pre> <p>And the many-to-many mapping with a join table and without a navigation property works (i.e. there is no Students.Courses property specified on <code>WithMany()</code>)</p> <pre><code>modelBuilder.Entity&lt;Course&gt;() .HasMany(c =&gt; c.Students) .WithMany() .Map(StoreTableName.FromString("Courses_Students"), (c, s) =&gt; new { CourseID = c.CourseID, StudentID = s.StudentID}); </code></pre> <p>But I'm having trouble mapping the other relationship that doesn't have a join table. This obviously isn't right:</p> <pre><code>modelBuilder.Entity&lt;Course&gt;().HasMany(c =&gt; c.Meetings).WithMany(); </code></pre> <p>Because it wants a join table: <code>Invalid object name 'dbo.Course_Meetings'</code>. I can add a <code>Course</code> property to the <code>Meeting</code> object and then use </p> <pre><code>modelBuilder.Entity&lt;Course&gt;() .HasMany(c =&gt; c.Meetings) .WithOptional(m =&gt; m.Course) .HasConstraint((c, m) =&gt; c.CoursID == me.CourseID); </code></pre> <p>But I'd like to do this without the navigation property. Is this possible with EF4 and an existing database?</p>
 

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