The problem is that when you have multiple relationships between two entities, EF Code First isn’t able to find out which navigation properties match up, unless, you tell it how, here is the code: public class Client { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int ID { get; set; } public string ClientName { get; set; } /****Change Nullable<int> … Read more
Here is how to find all the changed many-to-many relationships. I’ve implemented the code as extension methods: public static class IaExtensions { public static IEnumerable<Tuple<object, object>> GetAddedRelationships( this DbContext context) { return GetRelationships(context, EntityState.Added, (e, i) => e.CurrentValues[i]); } public static IEnumerable<Tuple<object, object>> GetDeletedRelationships( this DbContext context) { return GetRelationships(context, EntityState.Deleted, (e, i) => e.OriginalValues[i]); … Read more
Try using a NoTracking query instead. That way the objects arenever attached, so you don’t need to ‘detach’ which is when the graph is shredded: i.e. using (var creativeWorkshopEntities = new CreativeWorkshopEntities()) { creativeWorkshopEntities.Job.MergeOption = MergeOption.NoTracking; var q = from c in creativeWorkshopEntities.Job.Include(“Files”) where c.Id == jobId select c; var job = q.First(); return job; … Read more
Create your DbConnection manually and pass it to the DbContext constructor as follows: var conn = DbProviderFactories.GetFactory(“MY_CONN_PROVIDER”).CreateConnection(); conn.ConnectionString = “MY_CONN_STR”; new DbContext(conn, true); Notice the second parameter bool contextOwnsConnection is true. Since you don’t re-use the connection elsewhere, it lets the context manage the connection and Dispose() it when needed.
Here’s a nuget package I made earlier that generates lookup tables and applies foreign keys, and keeps the lookup table rows in sync with the enum: https://www.nuget.org/packages/ef-enum-to-lookup Add that to your project and call the Apply method. Documentation on github: https://github.com/timabell/ef-enum-to-lookup
Sadly EF does not know how to convert .ToString(). You must use the embedded function SqlFunctions.StringConvert: http://msdn.microsoft.com/en-us/library/dd466292.aspx Also there is no overload for int so you must typecast to double 🙁 var vendors = from v in Vendors select new { Code = SqlFunctions.StringConvert((double)v.VendorId) };
Whats wrong with two calls? They are small and quick queries. Databases are designed to support lots of small queries. A developing a complex solution to do one query for paging isn’t going give you much pay off.
Another option is using SqlFunctions.DateName, your code will be like this: var offer = (from p in dc.CustomerOffer join q in dc.OffersInBranch on p.ID equals q.OfferID where q.BranchID == singleLoc.LocationID let value = (p.OriginalPrice – p.NewPrice) * 100 / p.OriginalPrice orderby value descending select new { Title = p.OfferTitle, Description = p.Description, BestOffer = value, … Read more
You can write it using two from expressions like below: from a in Table1s from b in Table2s where a.ID1Table1 == b.ID1Table2 && a.ID2Table1 == b.ID2Table2 select new {a.ID1Table1, a.ID2Table1, a.Value1Table1, b.ID3Table2, b.Value1Table2} Using join: from a in Table1s join b in Table2s on new{PropertyName1 = a.ID1Table1, PropertyName2 = a.ID2Table1} equals new{PropertyName1 = b.ID1Table2, PropertyName2 … Read more
Use the context constructor overload that takes the connection string as a parameter.