How do I add a new entity that has a property which references an entity that is already created in a database?

I have a Project table and a Organization table.

Project has a many to one relationship with Organization.

Project has a scalar property OrganizationName that references the primary key Name in Organization

I have a create view which is strongly typed to the Project model.

I collect input for the Project.Organization.Name property like so:

<div class="editor-label">
        @Html.Label("Organization Name")
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Organization.Name)
        @Html.ValidationMessageFor(model => model.Organization.Name)
    </div>

The controller handles the post like so :

[HttpPost]
    public ActionResult Create(Project project)
    {
        if (ModelState.IsValid)
        {
开发者_运维知识库            db.Projects.AddObject(project);

            db.SaveChanges();
            return RedirectToAction("Index");
        }

        return View(project);
    }

How can I check to see if the new project.Organization.Name is already in the database? If it is, I want the new project to reference that tuple in the database and not attempt to add it again.

1. Add a UNIQUE constraint to the table. In a multi-user environment, that's the only way to be sure.
2. If you must know on the client, query the DB.

Like this:

[HttpPost]
public ActionResult Create(Project project)
{
    if (ModelState.IsValid)
    {
        var org = db.Organizations.SingleOrDefault(o => o.Name.Equals(project.Organization.Name, StringComparison.CurrentCultureIgnoreCase));
        if (org != null)
        {
            project.Organization = org;
        }
        db.Projects.AddObject(project);

        db.SaveChanges();
        return RedirectToAction("Index");
    }

    return View(project);
}