Ef core hasconversion enum example. I'm Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. . Please see Microsoft docs on EF Inheritance. EF Core 5 can accommodate the many-to-many relationship without having to define the SeriesGenre entity, where a Series simply has a collection of Genre, then configured with a HasMany(x => x. Property(e => e. By default, EntityFrameworkCore seems to store enum as int instead of string. As an example, I have the following enum Entity Framework (EF) Core, provides a powerful feature called HasConversion that simplifies this process. UserRole. HasConversion<int>() 会使 EF Core 将布尔值转换为数值零和一： This page documents API and behavior changes that have the potential to break existing applications updating from EF Core 7 to EF Core 8. 0 with the method HasConversion. When using EF Core, the easiest way to accomplish this goal is to use an enum as the type for the property. Metadata. The abstract member HasConversion : Type -> Microsoft. The same goes for lookup tables. another of the same type (for example, encrypting strings) or from a value of one type to a value of another type (for example, converting enum values to and from strings in the HasConversion (new OrderLineIdValueConverter ()); builder Currently, there's nothing prevent an enum with the [Flags] attribute from also having a conversion to string when configuring the model: HasConversion<string>() This works fine for client side evaluations but for server side, an issue arises when using enum. Himanshu For example, enum to string conversions are used as an example above, but EF Core will actually do this automatically when the provider type is configured as string using the generic type of I'm trying to set String-Enum value converter to all enum properties of all entities in my EF Core Code-First project. But I can't reproduce the exact case - I'm getting translation to CASE WHEN . 1 using a User model with a UserStatus property as an example. You can use the built-in EnumToStringConverter<> to automatically convert an Enum to string, and vice versa. Genres). It worked, as supposed to but the field in the created table that refers to the enumerator is a simple int. You can have it backed by a string by using : SmartEnum<TestEnum, string>. Now, we are able to map custom . ToString() value, EF Core version: Microsoft. EntityFrameworkCore v2. EF Core does not allow adding migrations for owned entities with enum sub-types that have value converters. NET Core Tutorials For Beginners and Professionals Global Configurations in Entity Framework Core using Fluent API: In this article, I will discuss How to Implement Global Configurations in Entity Framework Core (EF Core) using Fluent API with Examples. One field is a Char(1) with 'X' for true. Change tracking means that EF Core automatically determines what changes were performed by the application on a loaded entity instance, so that those changes That's it! User. This is represented by the ConfigurationSource enum. still wrong translation, but both enum constants are not converted to strings. Builders. NET type to a column, and the In the EF Core DbContext, override the OnModelCreating method and use the HasConversion or HasConversion method to register value converters for specific properties. References. EntityFrameworkCore. HasConversion or something i get this error: EF Core 2. Define the PostgreSQL Enum type in the database: Ensure that the PostgreSQL Enum type is created in your database. x I could do that cast and still do filtering which would be executed on SQL Server side. I’ve been diving into Entity Framework Core 5 and learning all I can about the object-relational mapper’s (ORM) inner-workings. Therefore, we have marked this feature as internal for EF Core 6. Table Per Type (TPT) Inheritance in Entity Framework Core Seems someone has been struggling with that and found solution. And usually I left it it like this, but recently I started wondering if was doing it right. Note that this configuration will be applied to both standard enum and nullable enum types without the need for any special logic to account for the nullable case. NET type to a column, and the other way around. HasConversion<string>() in your OnModelCreating() method within your Using the description Property to declare a column as enum (Enum<MyEnumName>) and the t4‘s will recognize it and type it as the given enum There are significant problems when executing queries that either convert nulls in the database to non-nulls in code or vice-versa. Entity Framework Core (EF Core) supports different types of inheritance mapping strategies to represent inheritance hierarchies in the database, one of which is Table Per Type (TPT). 1+ supports Value Conversions. But I’m including it as an example in case you need something like this for some other explicit conversion. HasConversion<string>() (or manually with an EnumToStringConverter<>), Entity Framework public static PropertyBuilder HasJsonConversion(this PropertyBuilder propertyBuilder) ParameterExpression parameter1 = With EF core 2. Smart Enums can be used when a enum needs In many cases EF will choose the appropriate built-in converter based on the type of the property in the model and the type requested in the database, as shown above for enums. So instead of defining two lambdas When querying an entity with an enum field that has been mapped with . I've added a . What exact EF Core version are you using? – I've followed MSDN on how to handle enumerations in Code First for EF6. The problem is that the string value IS NOT equivalent to the Enum . It supports implicit casts, etc. PropertyBuilder override In the EF Core DbContext, override the OnModelCreating method and use the HasConversion or HasConversion method to register value converters for specific properties. You can still use it, but you will ge I'm converting an old SQL Server DB design to EF Core 2. This causes the EF Core provider to create your enum type, mood, with two labels: happy and sad. Register a value converter. If you need to store a string representation (not recommended, but sometimes necessary), you can add a custom converter in the fluent API to What's more, this is such a common scenario, EF Core includes a conversion class called EnumToStringConverter that does this for us. Note The table WineType is not used in code, it is for a T4 template discussed later, for now we are only interested in the Wine table. Figure 1. However, I would like to With Entity Framework Core (EF Core), value conversions provide a powerful way to seamlessly convert data between its in-memory representation and its database format. When dealing with databases, there are times when you want a column to only allow certain values. Before specifying the conversion, the types need to be convertable. , works I am trying to do Enum conversion in my dataContext. The missing piece was adding the . Using this method, two delegates can be assigned to convert the . String". Even if your database enum is created, Npgsql has to know about it, and especially about your CLR enum type that should be mapped to it: Currently (EF Core 3. HasConversion however it is not working. One slip up in the code though; the converter has a type constraint for class so you can't use it on IList<Address>. We will cover practical scenarios like converting enums to strings, encrypting sensitive data, and Enum support in EF Core is quite extensive, in this article I’ll cover how to use an enum as a Primary Key, as well as storing the integer and string value of the enum in a column. Asking for help, Nice solution! Tried it and it works. In this post, we will add a new column to an entity that is of an enum type, set the default value, and create the migration script. 1. The HasConversion method in EF Core allows developers to define a In this story, we will explore the ins and outs of value conversions in EF Core. See: Store a Dictionary as a JSON string using EF Core 2. Make sure to review earlier breaking changes if updating from an earlier version of EF Core: Breaking changes in EF Core 7; Breaking changes in EF Core 6; Target Framework. public enum FooStatus {Value1, Value2} That's my whole point :) In EF Core 2. Just add [Column] attribute to your enum field and The above example, the enum is backed by an int value. Identity)] public int Id { get; set; } [Required] public string Name { get; set; } [Required] public Dictionary<string, string> Below an example that fails. InvalidCastException: 'Unable to cast object of type 'System. The values are not converted and after a change and trying to save I get "Object of type 'System. We covered how to define the enum, how to use it in a model class, how to configure it in EF Core, and how to query the database to retrieve users with a specific status. 21. For example: protected override void OnModelCreating HasConversion(ValueConverter) Configures the property so that the property value is converted to and from the database using the given ValueConverter. Value converters allow property values to be converted when reading from or writing to the database. WithMany() relationship Entity Framework Core (EF) 2. 1 HasConversion on all properties of type datetime. If you are using Entity Framework Core Migrations, after making this change you can add a new migration and check that an alter command is generated for all enums in your data model. The Enum sub-types work just fine for the owned types, the problem however occurs when say an EnumToStringConverter is applied to EF Core supports custom conversions from a . builder. See this comment: For anyone watching this issue: there are significant problems when executing queries that either convert nulls in the database to non-nulls in code or vice-versa. In the EF Core DbContext, override the OnModelCreating method and use the HasConversion or HasConversion method to register Here is a practical implementation example of TPH. . We will want to use two classes — one for HouseSize and another for House. HasFlags() in a query since the generated SQL attempts to perform a bitwise & operation on a SQL string Saving an enum as an int. CreatedDate) . NET types to a type the database understands and vice versa. HasConversion(Type) EF Core will create table Profiles with columns Id (int) and Type (int). I can do this manually like this: protected override void Benefits of Using Value Converters for Enums in EF Core. 🥳 It's called Pre-convention model configuration. Value conversions in EF Core; Enums in C# EF Core example In this example we want to associate wines with wine types in a SQL-Server database table. Int32' to type Background. Entity<ESDataQuotation>() . I've got most of the way in implementing Value Converters in my test proj Apparently a problem. Because now theoretically someone can open the database, update the Type column to anything and it in best case scenario it will cause database to be inconsistent, but in the worst case scenario it will break the application. Share. This conversion can be from one value to another of the same type (for example, encrypting strings) or fro I recently learned how to convert enums to string at the database level in EF Core (using . The DB design is not practical to change. For example, if you have an enum representing user A Smart Enum is an enhancement of the C# enum that provides a strongly typed and object oriented approach to enum types. So, now we know how we want the SQL to look, let’s go back to our C# model and set them up so that EF can use the enums in the same way. Here’s an implementation Is there a data-attribute approach for the HasConversion so that we can write this just once in the Entity and not have to repeat it in every Context it's used in? entity Numeric columns are handled directly by EF core. NET 7) using the HasConversion method. Mapping your enum. With EF Core 5, the newer ORM has Since the underlying database column type is string, association value converter is the correct mapping (by default EF Core maps enums to int). e. HasConversion(v 1. EF Core also provides built-in value converters for common scenarios, such as converting enums to strings or integers. If you need to store a string You can also use the built-in . 1 with a view to using it in the company I work for's business applications. In this post I discuss using strongly-typed IDs with EF Core by using value converters. Member for instance will be EF Core keeps track of how every piece of configuration was made. status END = 2, i. Using value converters in EF Core for enums offers several advantages, which include: Flexibility: Value converters Enum support in EF Core is quite extensive, in this article I’ll cover how to use an enum as a Primary Key, as well as storing the integer and string value of the enum in a column. However, it always give me System. Value Here's an example of how to use the HasConversion method to convert an enum value to a string: In this example, we define a MyEnum enum and a MyEntity class with a EF Core supports custom conversions from a . This will cause the appropriate migration to be created. In this article, we explored how to use enums in EF Core 3. In your DB Context class you can By leveraging the EF Core's HasConversion method we specify how values should be converted when written to or retrieved from the database. For the second enum, AddressType I don’t explicitly need to convert it from an enum to an int, Entity Framework will do this automatically (as pointed out to me in this tweet). Follow answered Sep 14, 2021 at 0:30. NET type to a column since EF Core 5. This long-awaited Please read our previous article discussing Table Per Hierarchy (TPH) Inheritance in EF Core with Examples. I am trying to use EntityFrameworkCore ORM to interact with my databases. The difference here is the way of identifying Enum type properties, and due to the lack of easy public way of getting entity type builder (this property builder), the direct usage of SetProviderClrType metadata API instead of more 在许多情况下，EF 将根据模型中属性的类型和在数据库中请求的类型，选择适当的内置转换器，正如上面的枚举转换示例所示。 例如，对 bool 属性使用 . You can do this using a migration script or by running a SQL script. The different kinds of configuration are: I think the problem is that maybe you expect too much of EF :( SUGGESTION (one of several different options): Add a "serialize()" and a "deserialize()" method to class ObjectA, When querying an entity with an enum field that has been mapped with . 1 introduced a new feature called Value Conversion. Wine model where WineType is an enum. THEN 2 ELSE e. I'm currently trialing Entity Framework Core 2. 4 The solution is to factory the conversion code into methods and then call those in HasConversion. 1 The definition of the entity is as follows: public class PublishSource { [Key] [DatabaseGenerated(DatabaseGeneratedOption. 0. HasConversion<string>() (or manually with an EnumToStringConverter<>), Entity Framework I created enum values on postgresql and mapped this to my log table My Log model is: When I try to cast to string or run . HasConversion<string>() on the enum property. 1 the DateTimeKindEntityMaterializerSource no longer works but we can actually do this. Provide details and share your research! But avoid . I'd prefer a second table to be produced, the values of which would follow the definition of the enumerator in C# code. 7) there is no other way than the one described in EF CORE 2. For Numeric columns are handled directly by EF core. It needs to be a concrete HasConversion (new EnumToStringConverter < TodoStatus >()); } } In the above example, there is a sample TodoContext database context class that has a set of Todo and Update: Actually I found a new feature in EF Core 6 that can be used for central configuration. So something like this is a must. UserRole stays as an enum type in our C# codebase while in the database it gets saved as corresponding string values. Whenever I add a where condition with a raw enum value, like in the below example, it works It seems like this is an issue in the PostgreSQL EF Core provider. Boolean' cannot be converted to type 'System. Improve this answer. Explicit enum to string conversions would make your code messy and you'd have to keep parsing values. We also want our enum, which we’ll suffix with ‘Enum’ to make the distinction between that type and the entity name: Edit : This feature is available from EF Core 6, but bugged. EF Core 8 targets . NET 8. 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