Lets say I would implement a Table Per Hierarchy for a class where I would store subclasses of this type distinguished by a discriminator (~ 5 types).
Some subclasses will have their own ICollections and some wont, so this will not be specified in the superclass. Im currenly only able to fetch the data that is directly stored in the table but unable to fetch the collection of this subclass (length of collection will be 0)
Any thoughts on how I would be able to fill in this list when I fetch this specific subclass (with specific discriminator) object from the database?
Here is a fully working sample console project, that demonstrates this approach:
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
namespace IssueConsoleTemplate
{
public class IceCream
{
public int IceCreamId { get; set; }
public string Name { get; set; }
}
public class IceCreamAsDrink : IceCream
{
public string DrinkName { get; set; }
}
public class IceCreamWithToppings : IceCream
{
public ICollection<Topping> Toppings { get; set; } = new HashSet<Topping>();
}
public class Topping
{
public int ToppingId { get; set; }
public string Name { get; set; }
public int IceCreamWithToppingsIceCreamId { get; set; } // <-- use this exact
// name or use the
// Fluent API
public IceCreamWithToppings IceCreamWithToppings { get; set; }
}
public class Context : DbContext
{
public DbSet<IceCream> IceCreams { get; set; }
public DbSet<IceCreamAsDrink> IceCreamsAsDrink { get; set; }
public DbSet<IceCreamWithToppings> IceCreamsWithToppings { get; set; }
public DbSet<Topping> Toppings { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder
.UseSqlServer(
#"Data Source=.\MSSQL14;Integrated Security=SSPI;Initial Catalog=So63087805")
.UseLoggerFactory(
LoggerFactory.Create(
b => b
.AddConsole()
.AddFilter(level => level >= LogLevel.Information)))
.EnableSensitiveDataLogging()
.EnableDetailedErrors();
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<IceCreamWithToppings>()
.HasMany(e => e.Toppings)
.WithOne(e => e.IceCreamWithToppings)
.HasForeignKey(e => e.IceCreamWithToppingsIceCreamId);
modelBuilder.Entity<IceCream>().HasData(
new IceCream
{
IceCreamId = 1,
Name = "Basic Vanilla"
});
modelBuilder.Entity<IceCreamAsDrink>().HasData(
new IceCreamAsDrink
{
IceCreamId = 2,
Name = "Vanilla Ice Coffee",
DrinkName = "Coffee"
});
modelBuilder.Entity<IceCreamWithToppings>().HasData(
new IceCreamWithToppings
{
IceCreamId = 3,
Name = "Vanilla With Sprinkles"
});
modelBuilder.Entity<Topping>().HasData(
new Topping
{
ToppingId = 1,
Name = "Chocolate Sprinkles",
IceCreamWithToppingsIceCreamId = 3
},
new Topping
{
ToppingId = 2,
Name = "Whipped Cream",
IceCreamWithToppingsIceCreamId = 3
});
}
}
internal static class Program
{
private static void Main()
{
using var context = new Context();
context.Database.EnsureDeleted();
context.Database.EnsureCreated();
var allIceCreams = context.IceCreams
.OrderBy(i => i.IceCreamId)
.ToList();
var iceCreamsAsDrink = context.IceCreamsAsDrink
.ToList();
var iceCreamsWithToppings = context.IceCreamsWithToppings
.Include(i => i.Toppings)
.ToList();
Debug.Assert(allIceCreams.Count == 3);
Debug.Assert(iceCreamsAsDrink.Count == 1);
Debug.Assert(iceCreamsWithToppings.Count == 1);
Debug.Assert(iceCreamsWithToppings[0].Toppings.Count == 2);
}
}
}
If you want to use conventions for the foreign key between Topping and IceCreamWithToppings, then the foreign key needs to be named <DerivedType><PrimaryKeyOnBaseType>, so IceCreamWithToppingsIceCreamId in this case.
Alternatively, just define the relationship using the Fluent API:
public class Topping
{
public int ToppingId { get; set; }
public string Name { get; set; }
public int MyForeignKeyToIceCream { get; set; } // <-- non-convention name
public IceCreamWithToppings IceCreamWithToppings { get; set; }
}
public class Context : DbContext
{
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<IceCreamWithToppings>()
.HasMany(e => e.Toppings)
.WithOne(e => e.IceCreamWithToppings)
.HasForeignKey(e => e.MyForeignKeyToIceCream);
}
}
In EF Core 2.0, we have the ability to derive from IEntityTypeConfiguration for cleaner Fluent API mappings (source).
How can I extend this pattern to utilize a base entity? In the example below, how can I have a BaseEntityConfiguration to reduce duplication in LanguageConfiguration and MaintainerConfiguration, modifying properties that are in the BaseEntity only in the BaseEntityConfiguration? What would such a BaseEntityConfiguration look like; and how would it be used, if at all, in OnModelCreating()? See the TODOs in-code near the end of the example.
Example:
public abstract class BaseEntity
{
public long Id { get; set; }
public DateTime CreatedDateUtc { get; set; }
public DateTime? ModifiedDateUtc { get; set; }
}
public class Language : BaseEntity
{
public string Iso6392 { get; set; }
public string LocalName { get; set; }
public string Name { get; set; }
}
public class Maintainer : BaseEntity
{
public string Email { get; set; }
public string Name { get; set; }
}
public class FilterListsDbContext : DbContext
{
public FilterListsDbContext(DbContextOptions options) : base(options)
{
}
public DbSet<Language> Languages { get; set; }
public DbSet<Maintainer> Maintainers { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
//TODO: Possibly add something like BaseEntityConfiguration?
modelBuilder.ApplyConfiguration(new LanguageConfiguration());
modelBuilder.ApplyConfiguration(new MaintainerConfiguration());
}
}
public class LanguageConfiguration : IEntityTypeConfiguration<Language>
{
public void Configure(EntityTypeBuilder<Language> entityTypeBuilder)
{
//TODO: Move this to something like BaseEntityConfiguration?
entityTypeBuilder.Property(b => b.CreatedDateUtc).HasDefaultValueSql("CURRENT_TIMESTAMP");
}
}
public class MaintainerConfiguration : IEntityTypeConfiguration<Maintainer>
{
public void Configure(EntityTypeBuilder<Maintainer> entityTypeBuilder)
{
//TODO: Move this to something like BaseEntityConfiguration?
entityTypeBuilder.Property(b => b.CreatedDateUtc).HasDefaultValueSql("CURRENT_TIMESTAMP");
}
}
Something like this could work (untested)?
public abstract class BaseEntityTypeConfiguration<TBase> : IEntityTypeConfiguration<TBase>
where TBase : BaseEntity
{
public virtual void Configure(EntityTypeBuilder<TBase> entityTypeBuilder)
{
//Base Configuration
}
}
public class MaintainerConfiguration : BaseEntityTypeConfiguration<Maintainer>
{
public override void Configure(EntityTypeBuilder<Maintainer> entityTypeBuilder)
{
entityTypeBuilder.Property(b => b.CreatedDateUtc).HasDefaultValueSql("CURRENT_TIMESTAMP");
base.Configure(entityTypeBuilder);
}
}
There is another way to solve the problem, and that is to use Template Method Design Pattern. Like this:
public abstract class BaseEntityTypeConfiguration<TBase> : IEntityTypeConfiguration<TBase>
where TBase : BaseEntity
{
public void Configure(EntityTypeBuilder<TBase> entityTypeBuilder)
{
//Base Configuration
ConfigureOtherProperties(builder);
}
public abstract void ConfigureOtherProperties(EntityTypeBuilder<TEntity> builder);
}
public class MaintainerConfiguration : BaseEntityTypeConfiguration<Maintainer>
{
public override void ConfigureOtherProperties(EntityTypeBuilder<Maintainer> entityTypeBuilder)
{
entityTypeBuilder.Property(b => b.CreatedDateUtc).HasDefaultValueSql("CURRENT_TIMESTAMP");
}
}
With this way you don't need to write any single line in child configuration.
Another approach if you dont want to repeat the column Definitions for all of your Models that inherit from the same base Entity like this:
protected override void OnModelCreating(ModelBuilder modelBuilder){
modelBuilder.Entity<Order>()
.Property(b => b.CreatedDateTime)
.HasDefaultValueSql("CURRENT_TIMESTAMP ");
modelBuilder.Entity<Adress>()
.Property(b => b.CreatedDateTime)
.HasDefaultValueSql("CURRENT_TIMESTAMP ");
// …
}
is to find all the Entites that inhert from the base Entity, loop over them and call the generic Method as shown below, in which the redundant Logic is placed:
protected override void OnModelCreating(ModelBuilder modelBuilder){
foreach (Type type in GetEntityTypes(typeof(BaseEntity))){
var method = SetGlobalQueryMethod.MakeGenericMethod(type);
method.Invoke(this, new object[] { modelBuilder });
}
}
static readonly MethodInfo SetGlobalQueryMethod = typeof(/*your*/Context)
.GetMethods(BindingFlags.Public | BindingFlags.Instance)
.Single(t => t.IsGenericMethod && t.Name == "SetGlobalQuery");
public void SetGlobalQuery<T>(ModelBuilder builder) where T : BaseEntity{
builder.Entity<T>().Property(o => o.CreatedDateTime).HasDefaultValueSql("CURRENT_TIMESTAMP");
// Additional Statements
}
For the "GetEntityTypes" Method you need the Nuget Package „Microsoft.Extensions.DependencyModel“
private static IList<Type> _entityTypeCache;
private static IList<Type> GetEntityTypes(Type type)
{
if (_entityTypeCache != null && _entityTypeCache.First().BaseType == type)
{
return _entityTypeCache.ToList();
}
_entityTypeCache = (from a in GetReferencingAssemblies()
from t in a.DefinedTypes
where t.BaseType == type
select t.AsType()).ToList();
return _entityTypeCache;
}
private static IEnumerable<Assembly> GetReferencingAssemblies()
{
var assemblies = new List<Assembly>();
var dependencies = DependencyContext.Default.RuntimeLibraries;
foreach (var library in dependencies)
{
try
{
var assembly = Assembly.Load(new AssemblyName(library.Name));
assemblies.Add(assembly);
}
catch (FileNotFoundException)
{ }
}
return assemblies;
}
Its a bit hacky in my opinion, but works fine for me!
The source with more details:
https://www.codingame.com/playgrounds/5514/multi-tenant-asp-net-core-4---applying-tenant-rules-to-all-enitites
I'm late to the party, but this is what I did in the OnModelCreating method to achieve similar results.
Basically, I have (4) properties that inherit from a BaseEntity. Two of those are dates why two are strings.
For the dates, I wanted the default to be SQL's GETUTCDATE and the string to be "SystemGenerated." Using a static helper that allows me to retrieve the property name from BaseEntity in a strongly-typed manner, I grab the (4) property names. Then, I iterate over all of the iterate over all of the ModelBuilder entities after my primary mappings are set-up. This allows modelBuilder.Model.GetEntityTypes to return the entities that the modelBuidler is aware of. Then it's a matter of looking at the ClrType.BaseType to see if the type inherits from my BaseEntity and setting the defaults on the PropertyBuilder.
I tested this directly and through EF Migrations which confirmed that the proper SQL was generated.
var createdAtUtc = StaticHelpers.GetPropertyName<BaseEntity>(x => x.CreatedAtUtc);
var lastModifiedAtUtc = StaticHelpers.GetPropertyName<BaseEntity>(x => x.LastModifiedAtUtc);
var createdBy = StaticHelpers.GetPropertyName<BaseEntity>(x => x.CreatedBy);
var lastModifiedBy = StaticHelpers.GetPropertyName<BaseEntity>(x => x.LastModifiedBy);
foreach (var t in modelBuilder.Model.GetEntityTypes())
{
if (t.ClrType.BaseType == typeof(BaseEntity))
{
modelBuilder.Entity(t.ClrType).Property(createdAtUtc).HasDefaultValueSql("GETUTCDATE()");
modelBuilder.Entity(t.ClrType).Property(lastModifiedAtUtc).HasDefaultValueSql("GETUTCDATE()");
modelBuilder.Entity(t.ClrType).Property(createdBy).HasDefaultValueSql("SystemGenerated");
modelBuilder.Entity(t.ClrType).Property(lastModifiedBy).HasDefaultValueSql("SystemGenerated");
}
}
Here is the the static helper for getting property names for a given type..
public static string GetPropertyName<T>(Expression<Func<T, object>> expression)
{
if (expression.Body is MemberExpression)
{
return ((MemberExpression)expression.Body).Member.Name;
}
else
{
var op = ((UnaryExpression)expression.Body).Operand;
return ((MemberExpression)op).Member.Name;
}
}
I have two sets of objects
Objects that I use in C# client application:
public class EmployeeClient
{
public int Id { get; set; }
public int DepartmentId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string MiddleName { get; set; }
}
public class DepartmentClient
{
public int Id { get; set; }
public string Name { get; set; }
}
public class OrganizationClient
{
public int Id { get; set; }
public string Name { get; set; }
public List<DepartmentClient> Departments { get; set; }
public List<EmployeeClient> Employees { get; set; }
}
And DTOs:
public class EmployeeDto
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string MiddleName { get; set; }
}
public class DepartmentDto
{
public int Id { get; set; }
public string Name { get; set; }
public List<EmployeeDto> Employees { get; set; }
}
public class OrganizationDto
{
public int Id { get; set; }
public string Name { get; set; }
public List<DepartmentDto> Departments { get; set; }
}
I use AutoMapper and I need to configure mapping Client -> DTOs and DTOs -> Client.
I implemented mapping DTOs->Client like this:
public class DtoToClientMappingProfile: Profile
{
public DtoToClientMappingProfile()
{
CreateMap<EmployeeDto, EmployeeClient>();
CreateMap<DepartmentDto, DepartmentClient>();
CreateMap<OrganizationDto, OrganizationClient>()
.ForMember(dest => dest.Employees, opt => opt.ResolveUsing(src => src.Departments.SelectMany(d => d.Employees)))
.AfterMap(AfterMap);
}
private void AfterMap(OrganizationDto dto, OrganizationClient client)
{
foreach (var department in dto.Departments)
{
foreach (var employee in department.Employees)
{
var clientEmployee = client.Employees.First(e => e.Id == employee.Id);
clientEmployee.DepartmentId = department.Id;
}
}
}
}
It is not universal solution, but is works for me.
I've found only one option how mapping Client->DTOs could be implemented:
public class ClientToDtosMappingProfile : Profile
{
public ClientToDtosMappingProfile()
{
CreateMap<EmployeeClient, EmployeeDto>();
CreateMap<DepartmentClient, DepartmentDto>();
CreateMap<OrganizationClient, OrganizationDto>()
.AfterMap(AfterMap);
}
private void AfterMap(OrganizationClient client, OrganizationDto dto)
{
foreach (var employee in client.Employees)
{
var departmentDto = dto.Departments.First(d => d.Id == employee.DepartmentId);
if (departmentDto.Employees == null)
{
departmentDto.Employees = new List<EmployeeDto>();
}
var configuration = (IConfigurationProvider)new MapperConfiguration(cfg =>
{
cfg.AddProfiles(typeof(ClientToDtosMappingProfile));
});
var mapper = (IMapper)new Mapper(configuration);
var employeeDto = mapper.Map<EmployeeDto>(employee);
departmentDto.Employees.Add(employeeDto);
}
}
}
It works, but I do not like this solution because I should create instance of new Mapper every time I map objects. In my real code Employee has a lot of nested elements and mapping is configured in multiple profiles.
Any ideas how it could be implemented better?
I made my code a bit better using ResolutionContext. It allows not to create mappers in AfterMap function.
DtoToClientMappingProfile:
public class DtoToClientMappingProfile: Profile
{
public DtoToClientMappingProfile()
{
CreateMap<EmployeeDto, EmployeeClient>();
CreateMap<DepartmentDto, DepartmentClient>();
CreateMap<OrganizationDto, OrganizationClient>()
.ForMember(dest => dest.Employees, opt => opt.Ignore())
.AfterMap(AfterMap);
}
private void AfterMap(OrganizationDto dto, OrganizationClient client, ResolutionContext resolutionContext)
{
if (dto.Departments == null)
{
return;
}
client.Departments = new List<DepartmentClient>();
foreach (var department in dto.Departments)
{
var departmentClient = resolutionContext.Mapper.Map<DepartmentClient>(department);
client.Departments.Add(departmentClient);
if (department.Employees == null)
{
continue;
}
if (client.Employees == null)
{
client.Employees = new List<EmployeeClient>();
}
foreach (var employee in department.Employees)
{
var employeeClient = resolutionContext.Mapper.Map<EmployeeClient>(employee);
employeeClient.DepartmentId = department.Id;
client.Employees.Add(employeeClient);
}
}
}
ClientToDtosMappingProfile:
public class ClientToDtosMappingProfile : Profile
{
public ClientToDtosMappingProfile()
{
CreateMap<EmployeeClient, EmployeeDto>();
CreateMap<DepartmentClient, DepartmentDto>();
CreateMap<OrganizationClient, OrganizationDto>()
.AfterMap(AfterMap);
}
private void AfterMap(OrganizationClient client, OrganizationDto dto, ResolutionContext resolutionContext)
{
if (client.Employees == null)
{
return;
}
foreach (var employee in client.Employees)
{
var departmentDto = dto.Departments.First(d => d.Id == employee.DepartmentId);
if (departmentDto.Employees == null)
{
departmentDto.Employees = new List<EmployeeDto>();
}
var employeeDto = resolutionContext.Mapper.Map<EmployeeDto>(employee);
departmentDto.Employees.Add(employeeDto);
}
}
}
If you call AssertConfigurationIsValid, AM will complain about what it doesn't know how to map.
The problem seems to be that you don't have the information needed to fill the destination object in the source object.
You will need to add a resolver for each property AM complains about, like the ResolveUsing you already have, for example.
You also need to pass the extra information that's needed.
The result may not look good eventually because AM cannot rely on uniform objects to do its job, you have to tell it what to do.
Another way to go about it is to do the high level mapping in your own code and rely on AM only when the mapping is simple enough so AM can do it by itself. The more you customize AM, the less value you get from it.
I am creating a reusable library using .NET Core (targeting .NETStandard 1.4) and I am using Entity Framework Core (and new to both). I have an entity class that looks like:
public class Campaign
{
[Key]
public Guid Id { get; set; }
[Required]
[MaxLength(50)]
public string Name { get; set; }
public JObject ExtendedData { get; set; }
}
and I have a DbContext class that defines the DbSet:
public DbSet<Campaign> Campaigns { get; set; }
(I am also using the Repository pattern with DI, but I don't think that is relevant.)
My unit tests give me this error:
System.InvalidOperationException: Unable to determine the relationship
represented by navigation property 'JToken.Parent' of type
'JContainer'. Either manually configure the relationship, or ignore
this property from the model..
Is there a way to indicate that this is not a relationship but should be stored as a big string?
Going to answer this one differently.
Ideally the domain model should have no idea how data is stored. Adding backing fields and extra [NotMapped] properties is actually coupling your domain model to your infrastructure.
Remember - your domain is king, and not the database. The database is just being used to store parts of your domain.
Instead you can use EF Core's HasConversion() method on the EntityTypeBuilder object to convert between your type and JSON.
Given these 2 domain models:
public class Person
{
public int Id { get; set; }
[Required]
[MaxLength(50)]
public string FirstName { get; set; }
[Required]
[MaxLength(50)]
public string LastName { get; set; }
[Required]
public DateTime DateOfBirth { get; set; }
public IList<Address> Addresses { get; set; }
}
public class Address
{
public string Type { get; set; }
public string Company { get; set; }
public string Number { get; set; }
public string Street { get; set; }
public string City { get; set; }
}
I have only added attributes that the domain is interested in - and not details that the DB would be interested in; I.E there is no [Key].
My DbContext has the following IEntityTypeConfiguration for the Person:
public class PersonsConfiguration : IEntityTypeConfiguration<Person>
{
public void Configure(EntityTypeBuilder<Person> builder)
{
// This Converter will perform the conversion to and from Json to the desired type
builder.Property(e => e.Addresses).HasConversion(
v => JsonConvert.SerializeObject(v, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }),
v => JsonConvert.DeserializeObject<IList<Address>>(v, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }));
}
}
With this method you can completely decouple your domain from your infrastructure. No need for all the backing field & extra properties.
The key to making the the Change Tracker function correctly is to implement a ValueComparer as well as a ValueConverter. Below is an extension to implement such:
public static class ValueConversionExtensions
{
public static PropertyBuilder<T> HasJsonConversion<T>(this PropertyBuilder<T> propertyBuilder) where T : class, new()
{
ValueConverter<T, string> converter = new ValueConverter<T, string>
(
v => JsonConvert.SerializeObject(v),
v => JsonConvert.DeserializeObject<T>(v) ?? new T()
);
ValueComparer<T> comparer = new ValueComparer<T>
(
(l, r) => JsonConvert.SerializeObject(l) == JsonConvert.SerializeObject(r),
v => v == null ? 0 : JsonConvert.SerializeObject(v).GetHashCode(),
v => JsonConvert.DeserializeObject<T>(JsonConvert.SerializeObject(v))
);
propertyBuilder.HasConversion(converter);
propertyBuilder.Metadata.SetValueConverter(converter);
propertyBuilder.Metadata.SetValueComparer(comparer);
propertyBuilder.HasColumnType("jsonb");
return propertyBuilder;
}
}
Example of how this works.
public class Person
{
public int Id { get; set; }
[Required]
[MaxLength(50)]
public string FirstName { get; set; }
[Required]
[MaxLength(50)]
public string LastName { get; set; }
[Required]
public DateTime DateOfBirth { get; set; }
public List<Address> Addresses { get; set; }
}
public class Address
{
public string Type { get; set; }
public string Company { get; set; }
public string Number { get; set; }
public string Street { get; set; }
public string City { get; set; }
}
public class PersonsConfiguration : IEntityTypeConfiguration<Person>
{
public void Configure(EntityTypeBuilder<Person> builder)
{
// This Converter will perform the conversion to and from Json to the desired type
builder.Property(e => e.Addresses).HasJsonConversion<IList<Address>>();
}
}
This will make the ChangeTracker function correctly.
#Michael's answer got me on track but I implemented it a little differently. I ended up storing the value as a string in a private property and using it as a "Backing Field". The ExtendedData property then converted JObject to a string on set and vice versa on get:
public class Campaign
{
// https://learn.microsoft.com/en-us/ef/core/modeling/backing-field
private string _extendedData;
[Key]
public Guid Id { get; set; }
[Required]
[MaxLength(50)]
public string Name { get; set; }
[NotMapped]
public JObject ExtendedData
{
get
{
return JsonConvert.DeserializeObject<JObject>(string.IsNullOrEmpty(_extendedData) ? "{}" : _extendedData);
}
set
{
_extendedData = value.ToString();
}
}
}
To set _extendedData as a backing field, I added this to my context:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Campaign>()
.Property<string>("ExtendedDataStr")
.HasField("_extendedData");
}
Update: Darren's answer to use EF Core Value Conversions (new to EF Core 2.1 - which didn't exist at the time of this answer) seems to be the best way to go at this point.
For those using EF 2.1 there is a nice little NuGet package EfCoreJsonValueConverter that makes it pretty simple.
using Innofactor.EfCoreJsonValueConverter;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
public class Campaign
{
[Key]
public Guid Id { get; set; }
[Required]
[MaxLength(50)]
public string Name { get; set; }
public JObject ExtendedData { get; set; }
}
public class CampaignConfiguration : IEntityTypeConfiguration<Campaign>
{
public void Configure(EntityTypeBuilder<Campaign> builder)
{
builder
.Property(application => application.ExtendedData)
.HasJsonValueConversion();
}
}
I have made a solution based on Robert Raboud's contribution. The change made by me is that my implementation uses a HasJsonConversion method that depends on the System.Text.Json package rather than Newtonsofts library:
public static PropertyBuilder<T> HasJsonConversion<T>(this PropertyBuilder<T> propertyBuilder) where T : class, new()
{
var options = new JsonSerializerOptions
{
PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
WriteIndented = true,
AllowTrailingCommas = true,
PropertyNameCaseInsensitive = true
};
ValueConverter<T, string> converter = new ValueConverter<T, string>
(
v => JsonSerializer.Serialize(v, options),
v => JsonSerializer.Deserialize<T>(v, options) ?? new T()
);
ValueComparer<T> comparer = new ValueComparer<T>
(
(l, r) => JsonSerializer.Serialize(l, options) == JsonSerializer.Serialize(r, options),
v => v == null ? 0 : JsonSerializer.Serialize(v, options).GetHashCode(),
v => JsonSerializer.Deserialize<T>(JsonSerializer.Serialize(v, options), options)
);
propertyBuilder.HasConversion(converter);
propertyBuilder.Metadata.SetValueConverter(converter);
propertyBuilder.Metadata.SetValueComparer(comparer);
propertyBuilder.HasColumnType("LONGTEXT");
return propertyBuilder;
}
Note also that this implementation expects for the column to be LONGTEXT since I am using a MySQL setup.
Here's something I used
Model
public class FacilityModel
{
public string Name { get; set; }
public JObject Values { get; set; }
}
Entity
[Table("facility", Schema = "public")]
public class Facility
{
public string Name { get; set; }
public Dictionary<string, string> Values { get; set; } = new Dictionary<string, string>();
}
Mapping
this.CreateMap<Facility, FacilityModel>().ReverseMap();
DBContext
base.OnModelCreating(builder);
builder.Entity<Facility>()
.Property(b => b.Values)
.HasColumnType("jsonb")
.HasConversion(
v => JsonConvert.SerializeObject(v),
v => JsonConvert.DeserializeObject<Dictionary<string, string>>(v));
Could you try something like this?
[NotMapped]
private JObject extraData;
[NotMapped]
public JObject ExtraData
{
get { return extraData; }
set { extraData = value; }
}
[Column("ExtraData")]
public string ExtraDataStr
{
get
{
return this.extraData.ToString();
}
set
{
this.extraData = JsonConvert.DeserializeObject<JObject>(value);
}
}
here is the migration output:
ExtraData = table.Column<string>(nullable: true),
For developers, who work with EF Core 3.1 and meet such error ("The entity type 'XXX' requires a primary key to be defined. If you intended to use a keyless entity type call 'HasNoKey()'.") the solution is:
Move .HasConversion() method with it's lambda from:
OrderConfiguration : IEntityTypeConfiguration<T> to
OnModelCreating(ModelBuilder modelBuilder) in your DataContext.
// DbContext
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
var entityTypes = modelBuilder.Model.GetEntityTypes();
foreach (var entityType in entityTypes)
{
foreach (var property in entityType.ClrType.GetProperties().Where(x => x != null && x.GetCustomAttribute<HasJsonConversionAttribute>() != null))
{
modelBuilder.Entity(entityType.ClrType)
.Property(property.PropertyType, property.Name)
.HasJsonConversion();
}
}
base.OnModelCreating(modelBuilder);
}
Create an attribute to handle the properties of the entities.
public class HasJsonConversionAttribute : System.Attribute
{
}
Create extention class to find Josn properties
public static class ValueConversionExtensions
{
public static PropertyBuilder HasJsonConversion(this PropertyBuilder propertyBuilder)
{
ParameterExpression parameter1 = Expression.Parameter(propertyBuilder.Metadata.ClrType, "v");
MethodInfo methodInfo1 = typeof(Newtonsoft.Json.JsonConvert).GetMethod("SerializeObject", types: new Type[] { typeof(object) });
MethodCallExpression expression1 = Expression.Call(methodInfo1 ?? throw new Exception("Method not found"), parameter1);
ParameterExpression parameter2 = Expression.Parameter(typeof(string), "v");
MethodInfo methodInfo2 = typeof(Newtonsoft.Json.JsonConvert).GetMethod("DeserializeObject", 1, BindingFlags.Static | BindingFlags.Public, Type.DefaultBinder, CallingConventions.Any, types: new Type[] { typeof(string) }, null)?.MakeGenericMethod(propertyBuilder.Metadata.ClrType) ?? throw new Exception("Method not found");
MethodCallExpression expression2 = Expression.Call(methodInfo2, parameter2);
var converter = Activator.CreateInstance(typeof(ValueConverter<,>).MakeGenericType(typeof(List<AttributeValue>), typeof(string)), new object[]
{
Expression.Lambda( expression1,parameter1),
Expression.Lambda( expression2,parameter2),
(ConverterMappingHints) null
});
propertyBuilder.HasConversion(converter as ValueConverter);
return propertyBuilder;
}
}
Entity example
public class Attribute
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
[HasJsonConversion]
public List<AttributeValue> Values { get; set; }
}
public class AttributeValue
{
public string Value { get; set; }
public IList<AttributeValueTranslation> Translations { get; set; }
}
public class AttributeValueTranslation
{
public string Translation { get; set; }
public string CultureName { get; set; }
}
Download Source
For those who are working on entity framework core 5.0 and above. below can work if you are getting error like below
The entity type '{EntityName}' requires a primary key to be defined. If you intended to use a keyless entity type, call 'HasNoKey' in 'OnModelCreating'. The error is asking to define a primary key on the model
Try this
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder
.Entity<Person>(
eb =>
{
eb.Property(p => p.Addresses).HasConversion(
v => JsonConvert.SerializeObject(v, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }),
v => JsonConvert.DeserializeObject<IList<Address>>(v, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore })
);
});
}
----------------- 2022 Update -----------------
Hey there,
Just sharing an update from Dec/2022.
Recently, EF Core 7.0 was launched, containing one of the most awaited features called JSON Columns.
This new feature allows us for mapping aggregates (written from .NET types) into JSON documents.
Just remember that, In EF Core, aggregate types are defined using Owned Entity Types.
https://learn.microsoft.com/en-us/ef/core/modeling/owned-entities
Let's consider this scenario: A object called "LogDetail", that needs to be stored into a single column as a JSON, inside another object (or table) called "Log".
public class Log : BaseEntity
{
public string TraceID { get; set; } = string.Empty;
public string Code { get; set; } = string.Empty;
public LogDetail LogDetail { get; set; } = null!;
public string IpAddress { get; set; } = string.Empty;
}
public class LogDetail
{
public string InnerException { get; set; } = null!;
public string MemberMap { get; set; } = null!;
public string Message { get; set; } = null!;
public string Source { get; set; } = null!;
public string StackTrace { get; set; } = null!;
public string TypeMap { get; set; } = null!;
public string Path { get; set; } = null!;
}
By the end, all that you need is to configure the behavior on your configuration map class:
public sealed class LogMap : IEntityTypeConfiguration<Log>
{
public override void Configure(EntityTypeBuilder<Log> builder)
{
/* Owned Type Configurations */
builder.OwnsOne(e => e.LogDetail, options =>
{
options.ToJson("LOG_DETAIL");
});
}
}
The comment by #Métoule:
Be careful with this approach: EF Core marks an entity as modified only if the field is assigned to. So if you use person.Addresses.Add, the entity won't be flagged as updated; you'll need to call the property setter person.Addresses = updatedAddresses.
made me take a different approach so that this fact is obvious: use Getter and Setter methods, rather than a property.
public void SetExtendedData(JObject extendedData) {
ExtendedData = JsonConvert.SerializeObject(extendedData);
_deserializedExtendedData = extendedData;
}
//just to prevent deserializing more than once unnecessarily
private JObject _deserializedExtendedData;
public JObject GetExtendedData() {
if (_extendedData != null) return _deserializedExtendedData;
_deserializedExtendedData = string.IsNullOrEmpty(ExtendedData) ? null : JsonConvert.DeserializeObject<JObject>(ExtendedData);
return _deserializedExtendedData;
}
You could theoretically do this:
campaign.GetExtendedData().Add(something);
But it's much more clear that That Doesn't Do What You Think It Does™.
If you're using database-first and using some kind of class auto-generator for EF, then the classes will usually be declared as partial, so you can add this stuff in a separate file that won't get blown away the next time you update your classes from your database.
I have a lot of POCO classes that contain several virtual properties each. Something like this:
public class Policy
{
public int Id { get; set; }
public int EntityId { get; set; }
public int ProgramId { get; set; }
public string PolicyNumber { get; set; }
public DateTime EffectiveDate { get; set; }
public DateTime ExpirationDate { get; set; }
public virtual Entity Entity{ get; set; }
public virtual Program Program { get; set; }
public virtual ICollection<Transaction> Transactions { get; set; }
}
To make Dapper.Extensions work, I need to write a mapping for each of these classes, which is fine. My problem is, if there are any virtual properties inside a class, they need to be explicitly marked as ignored, which I always forget to do.
public sealed class PolicyMapper : BaseMapper<Policy>
{
public PolicyMapper()
{
Map(p => p.Entity).Ignore();
Map(p => p.Program).Ignore();
Map(p => p.Transactions).Ignore();
AutoMap();
}
}
What would be great for me, if the Dapper.Extensions library will automatically exclude virtual properties, if any, when mapped to the POCO class. There is an extension for Automapper that does something similar (link). Is there a way to do that for Dapper.Extensions library? Possibly something like this:
public sealed class PolicyMapper : BaseMapper<Policy>
{
public PolicyMapper()
{
IgnoreAllVirtual();
AutoMap();
}
}
I found my own solution. Since all my mapping classes derive from BaseMapper class, I decided to override AutoMap() method that will exclude virtual properties:
public class BaseMapper<T> : ClassMapper<T> where T : BaseClass
{
public BaseMapper()
{
}
protected override void AutoMap()
{
CustomAutoMap(null);
}
private void CustomAutoMap(Func<Type, PropertyInfo, bool> canMap)
{
Type type = typeof(T);
bool hasDefinedKey = Properties.Any(p => p.KeyType != KeyType.NotAKey);
PropertyMap keyMap = null;
foreach (var propertyInfo in type.GetProperties())
{
// Exclude virtual properties
if (propertyInfo.GetGetMethod().IsVirtual)
{
continue;
}
if (Properties.Any(p => p.Name.Equals(propertyInfo.Name, StringComparison.InvariantCultureIgnoreCase)))
{
continue;
}
if ((canMap != null && !canMap(type, propertyInfo)))
{
continue;
}
PropertyMap map = Map(propertyInfo);
if (!hasDefinedKey)
{
if (string.Equals(map.PropertyInfo.Name, "id", StringComparison.InvariantCultureIgnoreCase))
{
keyMap = map;
}
if (keyMap == null && map.PropertyInfo.Name.EndsWith("id", true, CultureInfo.InvariantCulture))
{
keyMap = map;
}
}
}
if (keyMap != null)
{
keyMap.Key(PropertyTypeKeyTypeMapping.ContainsKey(keyMap.PropertyInfo.PropertyType)
? PropertyTypeKeyTypeMapping[keyMap.PropertyInfo.PropertyType]
: KeyType.Assigned);
}
}
}
}