ApplyUniqueIndex

Adds a unique index, which is how a value is kept unique in the database rather than only in the code that writes it. Use ApplyIndex for an index that only serves queries.

Usage

Single.cs

using AlmightyShogun.EntityFrameworkCore.ModelBuilding;

modelBuilder.ApplyUniqueIndex<Account>(account => account.Email);

Composite.cs

using AlmightyShogun.EntityFrameworkCore.ModelBuilding;

modelBuilder.ApplyUniqueIndex<Membership>(membership => new
{
    membership.AccountId,
    membership.TeamId
});

Filtered.cs

using AlmightyShogun.EntityFrameworkCore.ModelBuilding;

modelBuilder.ApplyUniqueIndex<Account>(
    account => account.Slug,
    filter: "[Slug] IS NOT NULL"
);

WARNING

filter is raw SQL and its identifier quoting is provider-specific: [Slug] on SQL Server, "Slug" on PostgreSQL and SQLite, `Slug` on MySQL and MariaDB.

Parameters

index: Expression<Func<TEntity, object?>>
The property to index, or an anonymous object of properties for a composite index. A composite unique index constrains the combination, not each column on its own.

filter: string?
A provider-specific predicate limiting which rows the constraint covers. Worth setting over a nullable column on SQL Server, which treats two nulls as equal and refuses the second row without it. PostgreSQL, SQLite, MySQL and MariaDB allow repeated nulls.
Default: null

Returns

The ModelBuilder instance with the unique index configured.

Type signature

public ModelBuilder ApplyUniqueIndex<TEntity>(
    Expression<Func<TEntity, object?>> index,
    string? filter = null
) where TEntity : class;