EntityFramework.Explained

Because We Need to Talk About Kevin.

Runtime Behaviour

List Properties

EF Core does not detect in-place mutations to, for instance, a List<string> when only a value converter is used. The property reference remains unchanged, so change tracking is not triggered and SaveChanges() persists nothing.

var converter = new ValueConverter<List<string>, string>(
        v => string.Join(';', v),
        v => v.Split(';', StringSplitOptions.RemoveEmptyEntries).ToList()
    );
entityTypeBuilder.Property(c => c.StringListProperty)
    .HasConversion(converter);

Adding a ValueComparer<List<string>> to the mapping allows EF Core to detect in-place list mutations. The comparer inspects the list's contents, so SaveChanges() correctly persists changes without replacing the list instance.

var converter = new ValueConverter<List<string>, string>(
        v => string.Join(';', v),
        v => v.Split(';', StringSplitOptions.RemoveEmptyEntries).ToList()
    );
var comparer = new ValueComparer<List<string>>(
    (c1, c2) => c1!.SequenceEqual(c2!),
    c => c.Aggregate(0, (a, v) => HashCode.Combine(a, v.GetHashCode())),
    c => c.ToList()
);
entityTypeBuilder.Property(c => c.StringListProperty)
    .HasConversion(converter)
    .Metadata.SetValueComparer(comparer);

Schema

Default String Length

Sql Server

Generates nvarchar(max).

Sqlite

Generates TEXT.

String Nullability

Sql Server

string Generates NOT NULL. string? Generates NULL.

Sqlite

string Generates NOT NULL. string? Generates NULL.

Uni Directional One To Many With One Db Set

Because the entity used in the DbSet has a collection of another entity type, the latter are mapped as well.

Sql Server

EF infers and includes related entities in the schema even when only one side is explicitly registered in the DbContext.

Sqlite

Same behavior as SqlServer, relationship discovery pulls in the Blog entity despite only registering Post