I am quite new to EF Core 6.0. We currently have a projet to upgrade, we cannot change the actual tables (use by another program) so we use Database fisrt approch.
So I need to add some Permission on user (the database are in french) We curently have an UsagerEW table (user table) and we add an Permission Table and an joint table PermissionUsagerEW for the Many2Many. After doing Scaffold-dbContect here is the result:
UsagerEW (primary key is Code_Int)
public partial class UsagerEW
{
public UsagerEW()
{
PermissionUsagerEW = new HashSet<PermissionUsagerEW>();
RefreshToken = new HashSet<RefreshToken>();
}
public string Code { get; set; }
public string Nom { get; set; }
public string Email { get; set; }
public string ModeLogin { get; set; }
public string PasswordTemp { get; set; }
public DateTime? PasswordTempExp { get; set; }
public int code_int { get; set; }
public virtual ICollection<PermissionUsagerEW> PermissionUsagerEW { get; set; }
}
Pemrssion and PermissionUsagerEW
public partial class Permission
{
public Permission()
{
PermissionUsagerEW = new HashSet<PermissionUsagerEW>();
}
public int id { get; set; }
public string code { get; set; }
public string description { get; set; }
public int? moduleId { get; set; }
public virtual Module module { get; set; }
public virtual ICollection<PermissionUsagerEW> PermissionUsagerEW { get; set; }
}
public partial class PermissionUsagerEW
{
public int id { get; set; }
public int permissionId { get; set; }
public int usagerCodeInt { get; set; }
public virtual Permission permission { get; set; }
public virtual UsagerEW usagerCodeIntNavigation { get; set; }
}
That compile and I can "navigate with include" from UsagerEW and get an list of PermissionUsagerEW for a specific UsagerEW.
Now like I am in EF COre 6.0 that supposed to support Many2Many
I add this nav propertie in the Permnission class
public virtual ICollection<UsagerEW> UsagerEW { get; set; }
and this in the UsagerEW class:
public virtual ICollection<Permission> Permission { get; set; }
But I got execution error either I just try to load some user wintout any include:
UsagerEW user = _EWContext.UsagerEW.Where(u=>u.Code == usagerId).SingleOrDefault();
System.InvalidOperationException: 'Cannot use table
'PermissionUsagerEW' for entity type 'PermissionUsagerEW
(Dictionary<string, object>)' since it is being used for entity type
'PermissionUsagerEW' and potentially other entity types, but there is
no linking relationship. Add a foreign key to 'PermissionUsagerEW
(Dictionary<string, object>)' on the primary key properties and
pointing to the primary key on another entity type mapped to
'PermissionUsagerEW'.'
The FK are detect by the scaffold:
modelBuilder.Entity<PermissionUsagerEW>(entity =>
{
entity.HasOne(d => d.permission)
.WithMany(p => p.PermissionUsagerEW)
.HasForeignKey(d => d.permissionId)
.OnDelete(DeleteBehavior.ClientSetNull)
.HasConstraintName("FK_PermissionUsager_Permission");
entity.HasOne(d => d.usagerCodeIntNavigation)
.WithMany(p => p.PermissionUsagerEW)
.HasForeignKey(d => d.usagerCodeInt)
.OnDelete(DeleteBehavior.ClientSetNull)
.HasConstraintName("FK_PermissionUsager_Usager");
});
Any idea?
---EDIT 1
I change your code to reflect the scaffolded PermissionUsagerEW table:
//--UsagewrEW
modelBuilder.Entity<UsagerEW>()
.HasKey(u => u.code_int);
modelBuilder.Entity<UsagerEW>()
.HasMany(u => u.Permissions)
.WithMany(p => p.Users)
.UsingEntity<PermissionUsagerEW>(
p => p.HasOne(e => e.permission)
.WithMany()
.HasForeignKey(e => e.permissionId),
p => p.HasOne(p => p.usagerCodeIntNavigation)
.WithMany()
.HasForeignKey(e => e.usagerCodeInt)
);
modelBuilder.Entity<PermissionUsagerEW>()
.HasOne(p => p.usagerCodeIntNavigation)
.WithMany()
.HasForeignKey(p => p.usagerCodeInt);
When testing with
UsagerEW user = _EWContext.UsagerEW.Where(u=>u.Code == usagerId).Include(u => u.Permissions).SingleOrDefault();
Now I got this error:
Microsoft.Data.SqlClient.SqlException: 'Invalid column name
'UsagerEWcode_int'.'
I think EF tries to link something automatically. I do not have any UsagerEWcode_int in my solution.
EDIT2:
There is the SQL generated. Wierd column name and some repetition...
SELECT [u].[code_int], [u].[Administrateur], [u].[Code], [u].[Email], [u].[EmpContact], [u].[Inactif], [u].[KelvinConfig], [u].[LectureSeule], [u].[ModeLogin], [u].[Nom], [u].[ParamRole], [u].[Password], [u].[PasswordTemp], [u].[PasswordTempExp], [u].[RestreintCommContrat], [u].[RestreintProjet], [u].[Role], [u].[UsagerAD], [u].[doitChangerPW], [u].[estSuperviseur], [u].[idSuperviseur], [u].[infoSession], [u].[paramRole2], [u].[permsGrps], [t].[id], [t].[Permissionid], [t].[UsagerEWcode_int], [t].[permissionId0], [t].[usagerCodeInt], [t].[id0], [t].[code], [t].[description], [t].[moduleId]
FROM [UsagerEW] AS [u]
LEFT JOIN (
SELECT [p].[id], [p].[Permissionid], [p].[UsagerEWcode_int], [p].[permissionId] AS [permissionId0], [p].[usagerCodeInt], [p0].[id] AS [id0], [p0].[code], [p0].[description], [p0].[moduleId]
FROM [PermissionUsagerEW] AS [p]
INNER JOIN [Permission] AS [p0] ON [p].[permissionId] = [p0].[id]
) AS [t] ON [u].[code_int] = [t].[usagerCodeInt]
WHERE [u].[Code] = #__usagerId_0
ORDER BY [u].[code_int], [t].[id]
You can configure direct Many-to-Many relationships with an existing database, and you can have the linking entity in the model or exclude it. There are several examples in the docs. And you can leave the foreign key properties in the model, or you can replace them with shadow properties. But the Scaffolding code doesn't do any of this for you. It creates the simplest correct model for the database schema.
Also you usually should rename the entities and properties to align with .NET coding conventions.
Anyway something like this should work:
public partial class UsagerEW
{
public string Code { get; set; }
public string Nom { get; set; }
public string Email { get; set; }
public string ModeLogin { get; set; }
public string PasswordTemp { get; set; }
public DateTime? PasswordTempExp { get; set; }
public int code_int { get; set; }
public virtual ICollection<Permission> Permissions { get; } = new HashSet<Permission>();
}
public partial class Permission
{
public int Id { get; set; }
public string Code { get; set; }
public string Description { get; set; }
public int? ModuleId { get; set; }
//public virtual Module module { get; set; }
public virtual ICollection<UsagerEW> Users { get; } = new HashSet<UsagerEW>();
}
public partial class PermissionUsagerEW
{
public int Id { get; set; }
public int PermissionId { get; set; }
public int UsagerCodeInt { get; set; }
public virtual Permission Permission { get; set; }
public virtual UsagerEW User { get; set; }
}
public class Db : DbContext
{
protected override void OnModelCreating(ModelBuilder builder)
{
builder.Entity<UsagerEW>()
.HasKey(u => u.code_int);
builder.Entity<UsagerEW>()
.HasMany(u => u.Permissions)
.WithMany(p => p.Users)
.UsingEntity<PermissionUsagerEW>(
p => p.HasOne(e => e.Permission)
.WithMany()
.HasForeignKey(e => e.PermissionId),
p => p.HasOne(p => p.User)
.WithMany()
.HasForeignKey( e => e.UsagerCodeInt)
);
builder.Entity<PermissionUsagerEW>()
.HasOne(p => p.User)
.WithMany()
.HasForeignKey(p => p.UsagerCodeInt);
foreach (var prop in builder.Model.GetEntityTypes().SelectMany(e => e.GetProperties()))
{
prop.SetColumnName(char.ToLower(prop.Name[0]) + prop.Name.Substring(1));
}
base.OnModelCreating(builder);
}
But when you're working in a database-first workflow, there's a downside to deeply customizing the EF model: you loose the ability to regenerate the EF model from the database.
So you can use a "nice" customized EF model, or a "plain" scaffolded model. If you customize the model, you can no longer regenerate it, and need to alter it to match future database changes by hand.
You can apply some customizations, though, like the convention-based property-to-column and entity-to-table mappings in the example. But changing the generated "indirect many-to-many" to "direct many-to-many" will prevent you from regenerating the EF model through scaffolding.
I'm learning EF Core and the below is my three POCOs:
public class County
{
[Key]
public int cid { get; set; }
public string cname { get; set; }
}
public class City
{
[Key]
public int cid { get; set; }
public string cname { get; set; }
}
public class People
{
[Key]
public int pid { get; set; }
public string pname { get; set; }
public int cid { get; set; }
public City WhichCity { get; set; }
}
I'm expecting two foreign keys but only got one from City table. How to make it(using annotation or fluent API or whatever) except explicitly define a County variable to People class.
Just want to clarify: you don't need to have navigation properties, i.e., public City City { get; set; } in order to setup relationships. The only things you need are the foreign key and proper configurations.
I think the following configuration would work for you (not tested though):
Entities
Here I also purposely modified your existing classes to follow C# Naming Conventions, if you care. Remember, if you're doing Code First, that means you can have your classes however you want first. You think about persistence later on. Actually I will show you how you can rename classes' properties when you persist them to your database via Configurations.
public class County
{
public int Id { get; set; }
public string Name { get; set; }
}
public class City
{
public int Id { get; set; }
public string Name { get; set; }
}
public class People
{
public int Id { get; set; }
public string Name { get; set; }
public int CityId { get; set; }
// Optional
//public City City { get; set; }
public int CountyId { get; set; }
// Optional
//public County County { get; set; }
}
Configurations
Instead of using Data Annotation, you can use Fluent API with configurations to configure how you want to map your classes back to database.
public class CountyConfiguration : IEntityTypeConfiguration<County>
{
public void Configure(EntityTypeBuilder<County> builder)
{
builder.HasKey(x => x.Id); // Same as using [Key]
builder.Property(x => x.Id)
.HasColumnName("cid"); // If you want to rename to "cid"
builder.Property(x => x.Name)
.IsRequired() // If you want to mark that field required
.HasColumnName("cname"); // If you want to rename to "cname"
builder.ToTable("so_county"); // If you want to rename the table
}
}
public class CityConfiguration : IEntityTypeConfiguration<City>
{
public void Configure(EntityTypeBuilder<City> builder)
{
builder.HasKey(x => x.Id); // Same as using [Key]
builder.Property(x => x.Id)
.HasColumnName("cid"); // If you want to rename to "cid"
builder.Property(x => x.Name)
.IsRequired() // If you want to mark that field required
.HasColumnName("cname"); // If you want to rename to "cname"
builder.ToTable("so_city"); // If you want to rename the table
}
}
public class PeopleConfiguration : IEntityTypeConfiguration<People>
{
public void Configure(EntityTypeBuilder<People> builder)
{
builder.HasKey(x => x.Id); // Same as using [Key]
builder.Property(x => x.Id)
.HasColumnName("pid"); // If you want to rename to "pid"
builder.Property(x => x.Name)
.IsRequired() // If you want to mark that field required
.HasColumnName("pname"); // If you want to rename to "pname"
// Relationship
builder.HasOne<County>() // People has one County
.WithMany() // County has many people
.HasForeignKey<County>(x => x.CountyId); // Foreign key is CountyId
builder.HasOne<City>() // People has one City
.WithMany() // City has many people
.HasForeignKey<City>(x => x.CityId); // Foreign key is CityId
builder.ToTable("so_people"); // If you want to rename the table
}
}
And lastly, you need to apply those configurations OnModelCreating:
public class YourDbContext : DbContext
{
public DbSet<County> Counties { get; set; }
public DbSet<City> Cities { get; set; }
public DbSet<People> People { get; set; }
public YourDbContext(DbContextOptions<YourDbContext> options) : base(options) {}
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.ApplyConfiguration(new CountyConfiguration());
builder.ApplyConfiguration(new CityConfiguration());
builder.ApplyConfiguration(new PeopleConfiguration());
}
}
DISCLAIM: wrote it by hand. Not tested.
Is it possible to create 2 M:M relationships using the same join table?
I have the following situation and am receiving the exception:
Unhandled Exception: System.InvalidOperationException: Cannot create a relationship between 'ApplicationUser.ExpertTags' and 'UserTag.User', because there already is a relationship between 'ApplicationUser.StudyTags' and 'UserTag.User'. Navigation properties can only participate in a single relationship
In Tag:
public class Tag {
public Tag() {
Users = new List<UserTag>();
}
public int TagId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public ICollection<UserTag> Users { get; set; }
In ApplicationUser:
public class ApplicationUser : IdentityUser
{
public ApplicationUser()
{
StudyTags = new HashSet<UserTag>();
ExpertTags = new HashSet<UserTag>();
}
public string FirstName { get; set; }
public string LastName { get; set; }
public string Location { get; set; }
public ICollection<UserTag> StudyTags { get; set; }
public ICollection<UserTag> ExpertTags { get; set; }
}
In UserTag (CLR join):
public class UserTag
{
public string UserId { get; set; }
public ApplicationUser User { get; set; }
public int TagId { get; set; }
public Tag Tag { get; set; }
}
In ApplicationDbContext:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<UserTag>()
.HasKey(x => new { x.UserId, x.TagId });
modelBuilder.Entity<UserTag>()
.HasOne(ut => ut.User)
.WithMany(u => u.StudyTags)
.HasForeignKey(ut => ut.UserId);
modelBuilder.Entity<UserTag>()
.HasOne(ut => ut.User)
.WithMany(u => u.ExpertTags)
.HasForeignKey(ut => ut.UserId);
modelBuilder.Entity<UserTag>()
.HasOne(ut => ut.Tag)
.WithMany(t => t.Users)
.HasForeignKey(ut => ut.TagId);
}
Do I need to create separate CLR classes? Something like UserStudyTag and UserExpertTag?
Thanks!
Step down to SQL DB. You want to have table UserTag with one UserId field. How EF should guess, which records in this table are related to StudyTags and which to ExpertTags collections?
You should duplicate something.
Either split UserTag to two tables (UserStudyTag and UserExpertTag), or make two UserId fields in UserTag, say ExpertUserId and StudyUserId. Both nullable, with only one having some value in each record.
I have a set of 3 models, which is an odd many-to-many-ish relationship.
public class Metric {
public int Id { get; set; }
public string Name { get; set; }
// ...
}
public class ActionPlan {
public int Id { get; set; }
public string Name { get; set; }
public DateTime StartDate { get; set; }
//...
public virtual ICollection<Metric> Metrics { get; set; }
}
public class PlanMetric {
public int PlanId { get; set; }
public int MetricId { get; set; }
public decimal GoalValue { get; set; }
public virtual ActionPlan Plan { get; set; }
public virtual Metric Metric { get; set; }
}
I have the relationships mapped as follows:
public class PlanMetricMapping : EntityTypeConfiguration<PlanMetric> {
public PlanMetricMapping() {
ToTable("PlanMetric");
HasKey(m => new {
m.MetricId,
m.PlanId
});
Property(m => m.GoalValue)
.IsRequired()
.HasPrecision(10, 2);
HasRequired(m => m.Metric)
.WithMany()
.HasForeignKey(m => m.MetricId);
HasRequired(m => m.Plan)
.WithMany()
.HasForeignKey(m => m.PlanId);
}
}
public class ActionPlanMapping : EntityTypeConfiguration<ActionPlan> {
public ActionPlanMapping() {
ToTable("ActionPlan");
HasKey(m => m.Id);
// ...
//HasMany(m=>m.Metrics) // how do I get to this data?
}
}
The problem is
1) EF is creating an ActionPlan_Id field in my Metric table, and I'm not sure why.
2) I don't know how to set up my mapping to be able to navigation from a Plan to it's Metrics.
EF is creating an ActionPlan_Id field because you have
public virtual ICollection<Metric> Metrics { get; set; }
in your ActionPlan definition, which EF interprets as a one-to-many relationship between ActionPlan and Metric. It seems like you want
public virtual ICollection<PlanMetric> PlanMetrics { get; set; }
instead.
Then, in order to get to an ActionPlan's metrics, you could go through that collection, perhaps through a Select().
I have two entites:
public class Address
{
public int Id { get; set; }
public string FirstName { get; set;
public string LastName { get; set; }
}
public partial class Customer
{
public int Id { get; set; }
public string Email { get; set; }
public string Username { get; set; }
public virtual Address BillingAddress { get; set; }
public virtual Address ShippingAddress { get; set; }
}
Below are mapping classes:
public partial class AddressMap : EntityTypeConfiguration<Address>
{
public AddressMap()
{
this.ToTable("Addresses");
this.HasKey(a => a.Id);
}
}
public partial class CustomerMap : EntityTypeConfiguration<Customer>
{
public CustomerMap()
{
this.ToTable("Customer");
this.HasKey(c => c.Id);
this.HasOptional<Address>(c => c.BillingAddress);
this.HasOptional<Address>(c => c.ShippingAddress);
}
}
When database is generated, my 'Customer' table has two columns for 'BillingAddress' and 'ShippingAddress' properties. Their names are 'AddressId' and 'AddressId1'.
Question: how can I rename them to 'BillingAddressId' and 'ShippingAddressId'?
Basically you want to customize the FK column name in an independent association and this code will do this for you:
public CustomerMap()
{
this.ToTable("Customer");
this.HasOptional<Address>(c => c.BillingAddress)
.WithMany()
.IsIndependent().Map(m =>
{
m.MapKey(a => a.Id, "BillingAddressId");
});
this.HasOptional<Address>(c => c.ShippingAddress)
.WithMany()
.IsIndependent().Map(m =>
{
m.MapKey(a => a.Id, "ShippingAddressId");
});
}