The EF will create Nvarchar data type from a property of type String.
Is there a list of how other types are treated by EF and what they will be represented as in the DB created from the model ? Thank you,
Check that mapping table: SQL-CLR Type Mapping. You can also change that default behavior using DbType attribute:
[Column(DbType="NVarChar(10) NOT NULL")]
Related
I am using Entity Framework Core 7.0.0 and in my OnModelCreating method I am trying to specify a column to be of type nvarchar(max).
In EF6 (not Core!), we were able to do something like:
modelBuilder.Entity<Log>().Property(p => p.Errors).IsMaxLength();
However, I am not able to figure this out in EF Core. Is there something similar available in EF Core that I am missing?
I know that it would normally default all properties of type string to nvarchar(max) but I am overriding DbContext's ConfigureConventions with the following, to default all string to 50 characters:
configurationBuilder.Properties<string>().HaveMaxLength(50);
With help of [Column] data annotation:
[Column(TypeName = "nvarchar(MAX)")]
With help of Fluent API:
entity.Property(p => p.Errors)
.HasColumnName("YourColumnName")
.HasColumnType("nvarchar(MAX)");
HasColumnName: the HasColumnName attribute is applied to a property to specify the database column that the property should map to when the entity's property name and the database column name differ.
HasColumnType: the HasColumnType method is applied to a property to specify the data type of the column that the property should map to when the type differs from convention.
I cannot find any information for scaffolding a table which has a a JSONB column which should map to JsonDocument type property but instead maps to a string.
It is not an easily maintainable solution to have to manually replace every JSONB => string to JsonDocument.
Is there something I can do with the column type or maybe with the scaffold command to make JSONB columns automatically map to JsonDocument.
Database is POSTGRES and I'm using EntityframeworkCore.
PostgreSQL JSONB columns are scaffolded as .NET string properties - there's no easy way to change that at the moment. There are plans for more extensibility/customizability at the EF Core scaffolding level (https://github.com/dotnet/efcore/issues/4038), but at the moment you're going to have to change the CLR type yourself.
I've been looking at various Code First examples of TPT (Table Per Type) in Entity Framework.
I have an abstract base class with 4 concrete implementations, all of which share the exact same interface. These are being stored using EF in a single table named after the abstract base class.
What I wish to do is use the EF Discriminator column, but without using the automatic table creation in Code First, instead adding the configuration and mappings manually. Does anyone know if this would be possible and if so, what the type of the Discriminator column is (name, type, length, nullable, etc.) so I can create one manually?
Many thanks.
Currently I have class hierarchy defined with the Code First approach as follows.
E.F. has autogenerated a nvarchar(128) discriminator. It is not a key field.
How does Entity Framework determine what and what Type the discriminator field should be, and is it always the same, i.e. nvarchar? Is the discriminator at all accessible outside the database i.e. from LINQ to Entity?
Discriminator column is by default nvarchar because it stores names of your classes to differ between types - that is the whole point of this column: to allow EF knowing what class instance from your inheritance hierarchy it should create when it loads record from the database.
Discriminator column is not accessible by linq-to-entities. It is only used to map record to correct type.
I want to use a Money value object in my application. I have found several examples of a Money datatype. But I can't figure out how to use them with EF4. I would like to store each amount as a Decimal/CurrencyCode pair (where currencycode is a string - "USD", "SEK", etc) in the database. I tried creating a complexType but I couldn't get that to work. Is this possible?
It should be definitely possible. Your complex type is just pair of decimal and string property. It is exactly what complex type are used for. Depending on your approach you must do:
Database first:
You will define your database first. Your table will contain money and varchar columns representing your new type. When you update your EDMX model from database it will include it as scalar properties to your entity. You must remove those properties. Then go to model browser and create new complex type. Return back to entity and add complex property of your new complex type. And at the end you must go to entity mapping and map your complex type to those database columns.
Here is basic tutorial from MSDN but from unknown reason they didn't include such elementary details like screenshots. Here is some video from channel9.
Model first:
This is similar to database first but you don't have to deal with database creation and mapping. It will be generated for you.
Code first (EF 4.1):
You must create separate class for your complex type and use it as property in your entity. You should not need to map it by default - mapping should be infered. If it doesn't work you can map complext type either by using ComplextTypeAttribute annotation or by defining mapping in DbModelBuilder.
I can further extend approach you need to use if you provide more details.