entity framework many to many still execting foreign key after fluent api -

i've created entity framework m:m relationship between user identity class , class called group.

although i've given both classes icollection property linking other one, didn't automatically create many many table , i've instead created fluent api - groupusers table. appears ok.

when try register user, fails. looking @ sql generated appears expecting group_id field present in users table - not sure why it's looking in separate table.

the group class (entity has id property)

public class group : entity {     public group()     {         this.users = new hashset<user>();     }     [maxlength(100)]     public string name { get; set; }      public virtual icollection<user> users { get; set; } } 

the user class (customised application user class)

    public class user : identityuser<int, customuserlogin, customuserrole, customuserclaim> {     public user()     {         this.groups = new hashset<group>();     }     [required]     [maxlength(100)]     public string firstname { get; set; }     [required]     [maxlength(100)]     public string lastname { get; set; }      public virtual icollection<group> groups { get; set; }      public async task<claimsidentity> generateuseridentityasync(usermanager<user, int> manager, string authenticationtype)     {         // note authenticationtype must match 1 defined in cookieauthenticationoptions.authenticationtype         var useridentity = await manager.createidentityasync(this, authenticationtype);         // add custom user claims here         return useridentity;     } } 

as can see above both have property relationship other class.

fluent api:

            modelbuilder.entity<user>().hasmany(u => u.groups).withmany(g => g.users).map(x =>         {             x.mapleftkey("groupid");             x.maprightkey("userid");             x.totable("groupusers");         }); 

all above creates tables: user, group, , groupusers.

i have expected working is.

unfortunately, when try register user still looks expecting group_id present in user table:

exec sp_executesql n'select  [limit1].[id] [id],  [limit1].[firstname] [firstname],  [limit1].[lastname] [lastname],   [limit1].[email] [email],  [limit1].[emailconfirmed] [emailconfirmed],  [limit1].[passwordhash] [passwordhash],  [limit1].[securitystamp] [securitystamp],  [limit1].[phonenumber] [phonenumber],  [limit1].[phonenumberconfirmed] [phonenumberconfirmed],  [limit1].[twofactorenabled] [twofactorenabled],  [limit1].[lockoutenddateutc] [lockoutenddateutc],  [limit1].[lockoutenabled] [lockoutenabled],  [limit1].[accessfailedcount] [accessfailedcount],  [limit1].[username] [username],  [limit1].[group_id] [group_id] ---why here?? ( select top (1)      [extent1].[id] [id],      [extent1].[firstname] [firstname],      [extent1].[lastname] [lastname],      [extent1].[email] [email],      [extent1].[emailconfirmed] [emailconfirmed],      [extent1].[passwordhash] [passwordhash],      [extent1].[securitystamp] [securitystamp],      [extent1].[phonenumber] [phonenumber],      [extent1].[phonenumberconfirmed] [phonenumberconfirmed],      [extent1].[twofactorenabled] [twofactorenabled],      [extent1].[lockoutenddateutc] [lockoutenddateutc],      [extent1].[lockoutenabled] [lockoutenabled],      [extent1].[accessfailedcount] [accessfailedcount],      [extent1].[username] [username],      [extent1].[group_id] [group_id]     [dbo].[aspnetusers] [extent1]     ((upper([extent1].[username])) = (upper(@p__linq__0))) or ((upper([extent1].[username]) null) , (upper(@p__linq__0) null)) )  [limit1]',n'@p__linq__0 nvarchar(4000)',@p__linq__0=n'myemail@myemail.com' 

when run sql seperately, :

invalid column name 'group_id'.

any ideas why it's not working correctly , why group_id expected there, though it's specified in fluent api shouldn't be?

thanks,