Question
I followed the documentation on Postgres C# website.
When I run this code I get:
The entity type 'Bar' requires a primary key to be defined.
POCOs:
public class Foo
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
[Column(TypeName = "jsonb")]
public Bar Bar { get; set; }
}
public class Bar
{
public string Prop1 { get; set; }
public string Prop2 { get; set; }
}
My goal is to avoid using string as a property type of Bar and let the entity framework handle JSON serialize, deserialize. I don't want the Bar to be a separate table. I want it to be a JSON column on Foo.
Accepted Answer
After upgrading to .NET Core 3.0 from 2.2 everything worked fine. The following is the new csproj:
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>netcoreapp3.0</TargetFramework>
<AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
<AssemblyName>App</AssemblyName>
<RootNamespace>App</RootNamespace>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.App" />
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.0.0" />
<PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="3.0.0" />
</ItemGroup>
</Project>
Popular Answer
You need to create ValueConverter<Bar, string> or use function expressions directly in HasConversion in on OnModelCreating.
Example:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Foo>()
.Property(x => x.Bar)
.HasConversion(
v => JsonConvert.SerializeObject(v),
v => JsonConvert.DeserializeObject<Bar>(v));
base.OnModelCreating(modelBuilder);
}
Reference: https://docs.microsoft.com/en-us/ef/core/modeling/value-conversions
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