Add TableIndex and UniqueConstraint to the relational model.

Part of #12846

src/EFCore.Design/Migrations/Design/CSharpSnapshotGenerator.cs

@@ -646,7 +646,7 @@ protected virtual void GenerateKeys(
                 foreach (var key in keys.Where(
                     key => key != primaryKey
                            && (!key.GetReferencingForeignKeys().Any()
-                               || key.GetAnnotations().Any())))
+                               || key.GetAnnotations().Any(a => a.Name != RelationalAnnotationNames.UniqueConstraintMappings))))
                 {
                     GenerateKey(builderName, key, stringBuilder);
                 }
@@ -679,17 +679,31 @@ protected virtual void GenerateKey(
 
             using (stringBuilder.Indent())
             {
-                var annotations = key.GetAnnotations().ToList();
-
-                GenerateFluentApiForAnnotation(
-                    ref annotations, RelationalAnnotationNames.Name, nameof(RelationalKeyBuilderExtensions.HasName), stringBuilder);
-
-                GenerateAnnotations(annotations, stringBuilder);
+                GenerateKeyAnnotations(key, stringBuilder);
             }
 
             stringBuilder.AppendLine(";");
         }
 
+        /// <summary>
+        ///     Generates code for the annotations on a key.
+        /// </summary>
+        /// <param name="key"> The key. </param>
+        /// <param name="stringBuilder"> The builder code is added to. </param>
+        protected virtual void GenerateKeyAnnotations([NotNull] IKey key, [NotNull] IndentedStringBuilder stringBuilder)
+        {
+            var annotations = key.GetAnnotations().ToList();
+
+            IgnoreAnnotations(
+                annotations,
+                RelationalAnnotationNames.UniqueConstraintMappings);
+
+            GenerateFluentApiForAnnotation(
+                ref annotations, RelationalAnnotationNames.Name, nameof(RelationalKeyBuilderExtensions.HasName), stringBuilder);
+
+            GenerateAnnotations(annotations, stringBuilder);
+        }
+
         /// <summary>
         ///     Generates code for <see cref="IIndex" /> objects.
         /// </summary>
@@ -742,19 +756,34 @@ protected virtual void GenerateIndex(
                         .Append(".IsUnique()");
                 }
 
-                var annotations = index.GetAnnotations().ToList();
-
-                GenerateFluentApiForAnnotation(
-                    ref annotations, RelationalAnnotationNames.Name, nameof(RelationalIndexBuilderExtensions.HasName), stringBuilder);
-                GenerateFluentApiForAnnotation(
-                    ref annotations, RelationalAnnotationNames.Filter, nameof(RelationalIndexBuilderExtensions.HasFilter), stringBuilder);
-
-                GenerateAnnotations(annotations, stringBuilder);
+                GenerateIndexAnnotations(index, stringBuilder);
             }
 
             stringBuilder.AppendLine(";");
         }
 
+        /// <summary>
+        ///     Generates code for the annotations on an index.
+        /// </summary>
+        /// <param name="index"> The index. </param>
+        /// <param name="stringBuilder"> The builder code is added to. </param>
+        protected virtual void GenerateIndexAnnotations(
+            [NotNull] IIndex index, [NotNull] IndentedStringBuilder stringBuilder)
+        {
+            var annotations = index.GetAnnotations().ToList();
+
+            IgnoreAnnotations(
+                annotations,
+                RelationalAnnotationNames.TableIndexMappings);
+
+            GenerateFluentApiForAnnotation(
+                ref annotations, RelationalAnnotationNames.Name, nameof(RelationalIndexBuilderExtensions.HasName), stringBuilder);
+            GenerateFluentApiForAnnotation(
+                ref annotations, RelationalAnnotationNames.Filter, nameof(RelationalIndexBuilderExtensions.HasFilter), stringBuilder);
+
+            GenerateAnnotations(annotations, stringBuilder);
+        }
+
         /// <summary>
         ///     Generates code for the annotations on an entity type.
         /// </summary>

src/EFCore.Design/Migrations/Design/MigrationsCodeGenerator.cs

@@ -250,7 +250,9 @@ private IEnumerable<string> GetAnnotationNamespaces(IEnumerable<IAnnotatable> it
                 RelationalAnnotationNames.Views,
                 RelationalAnnotationNames.ViewMappings,
                 RelationalAnnotationNames.ViewColumnMappings,
-                RelationalAnnotationNames.ForeignKeyMappings
+                RelationalAnnotationNames.ForeignKeyMappings,
+                RelationalAnnotationNames.TableIndexMappings,
+                RelationalAnnotationNames.UniqueConstraintMappings
             };
 
             return items.SelectMany(

src/EFCore.Design/Scaffolding/Internal/CSharpDbContextGenerator.cs

@@ -471,6 +471,7 @@ private void GenerateKey(IKey key, IEntityType entityType, bool useDataAnnotatio
 
             var explicitName = key.GetName() != key.GetDefaultName();
             RemoveAnnotation(ref annotations, RelationalAnnotationNames.Name);
+            RemoveAnnotation(ref annotations, RelationalAnnotationNames.UniqueConstraintMappings);
 
             if (key.Properties.Count == 1
                 && annotations.Count == 0)
@@ -578,6 +579,8 @@ private void GenerateIndex(IIndex index)
 
             var annotations = index.GetAnnotations().ToList();
 
+            RemoveAnnotation(ref annotations, RelationalAnnotationNames.TableIndexMappings);
+
             if (!string.IsNullOrEmpty((string)index[RelationalAnnotationNames.Name]))
             {
                 lines.Add(

src/EFCore.Relational/Extensions/RelationalForeignKeyExtensions.cs

@@ -82,7 +82,7 @@ public static void SetConstraintName(
         /// </summary>
         /// <param name="foreignKey"> The foreign key. </param>
         /// <returns> The foreign key constraints to which the foreign key is mapped. </returns>
-        public static IEnumerable<IForeignKeyConstraint> GetConstraintMappings([NotNull] this IForeignKey foreignKey) =>
+        public static IEnumerable<IForeignKeyConstraint> GetMappedConstraints([NotNull] this IForeignKey foreignKey) =>
             (IEnumerable<IForeignKeyConstraint>)foreignKey[RelationalAnnotationNames.ForeignKeyMappings]
                 ?? Enumerable.Empty<IForeignKeyConstraint>();
     }

src/EFCore.Relational/Extensions/RelationalIndexExtensions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using JetBrains.Annotations;
@@ -109,5 +110,14 @@ public static void SetFilter([NotNull] this IConventionIndex index, [CanBeNull]
         /// <returns> The <see cref="ConfigurationSource" /> for the index filter expression. </returns>
         public static ConfigurationSource? GetFilterConfigurationSource([NotNull] this IConventionIndex index)
             => index.FindAnnotation(RelationalAnnotationNames.Filter)?.GetConfigurationSource();
+
+        /// <summary>
+        ///     Gets the table indexes to which the index is mapped.
+        /// </summary>
+        /// <param name="index"> The index. </param>
+        /// <returns> The table indexes to which the index is mapped. </returns>
+        public static IEnumerable<ITableIndex> GetMappedTableIndexes([NotNull] this IIndex index) =>
+            (IEnumerable<ITableIndex>)index[RelationalAnnotationNames.TableIndexMappings]
+                ?? Enumerable.Empty<ITableIndex>();
     }
 }

src/EFCore.Relational/Extensions/RelationalKeyExtensions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using JetBrains.Annotations;
@@ -88,5 +89,14 @@ public static void SetName([NotNull] this IConventionKey key, [CanBeNull] string
         /// <returns> The <see cref="ConfigurationSource" /> for the constraint name. </returns>
         public static ConfigurationSource? GetNameConfigurationSource([NotNull] this IConventionKey key)
             => key.FindAnnotation(RelationalAnnotationNames.Name)?.GetConfigurationSource();
+
+        /// <summary>
+        ///     Gets the unique constraints to which the key is mapped.
+        /// </summary>
+        /// <param name="key"> The key. </param>
+        /// <returns> The unique constraints to which the key is mapped. </returns>
+        public static IEnumerable<IUniqueConstraint> GetMappedConstraints([NotNull] this IKey key) =>
+            (IEnumerable<IUniqueConstraint>)key[RelationalAnnotationNames.UniqueConstraintMappings]
+                ?? Enumerable.Empty<IUniqueConstraint>();
     }
 }

src/EFCore.Relational/Metadata/ITable.cs

@@ -34,6 +34,16 @@ public interface ITable : ITableBase
         /// </summary>
         IEnumerable<IForeignKeyConstraint> ForeignKeyConstraints { get; }
 
+        /// <summary>
+        ///     Gets the unique constraints for this table.
+        /// </summary>
+        IEnumerable<IUniqueConstraint> UniqueConstraints { get; }
+
+        /// <summary>
+        ///     Gets the indexes for this table.
+        /// </summary>
+        IEnumerable<ITableIndex> Indexes { get; }
+
         /// <summary>
         ///     Gets the check constraints for this table.
         /// </summary>

src/EFCore.Relational/Metadata/ITableIndex.cs

@@ -0,0 +1,44 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+
+namespace Microsoft.EntityFrameworkCore.Metadata
+{
+    /// <summary>
+    ///     Represents a table index.
+    /// </summary>
+    public interface ITableIndex : IAnnotatable
+    {
+        /// <summary>
+        ///     Gets the name of the index.
+        /// </summary>
+        string Name { get; }
+
+        /// <summary>
+        ///     Gets the mapped indexes.
+        /// </summary>
+        IEnumerable<IIndex> MappedIndexes { get; }
+
+        /// <summary>
+        ///     Gets the table on with the index is declared.
+        /// </summary>
+        ITable Table { get; }
+
+        /// <summary>
+        ///     Gets the columns that are participating in the index.
+        /// </summary>
+        IReadOnlyList<IColumn> Columns { get; }
+
+        /// <summary>
+        ///     Gets a value indicating whether the index enforces uniqueness.
+        /// </summary>
+        bool IsUnique { get; }
+
+        /// <summary>
+        ///     Gets the expression used as the index filter.
+        /// </summary>
+        string Filter { get; }
+    }
+}

src/EFCore.Relational/Metadata/IUniqueConstraint.cs

@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+
+namespace Microsoft.EntityFrameworkCore.Metadata
+{
+    /// <summary>
+    ///     Represents a unique constraint.
+    /// </summary>
+    public interface IUniqueConstraint : IAnnotatable
+    {
+        /// <summary>
+        ///     Gets the name of the unique constraint.
+        /// </summary>
+        string Name { get; }
+
+        /// <summary>
+        ///     Gets a value indicating whether this constraint is the primary key.
+        /// </summary>
+        bool IsPrimaryKey { get; }
+
+        /// <summary>
+        ///     Gets the mapped keys.
+        /// </summary>
+        IEnumerable<IKey> MappedKeys { get; }
+
+        /// <summary>
+        ///     Gets the table on with the unique constraint is declared.
+        /// </summary>
+        ITable Table { get; }
+
+        /// <summary>
+        ///     Gets the columns that are participating in the unique constraint.
+        /// </summary>
+        IReadOnlyList<IColumn> Columns { get; }
+    }
+}

src/EFCore.Relational/Metadata/Internal/Column.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 
@@ -57,6 +58,19 @@ public Column([NotNull] string name, [CanBeNull] string type, [NotNull] Table ta
         /// </summary>
         public override string ToString() => this.ToDebugString(MetadataDebugStringOptions.SingleLineDefault);
 
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public static string Format([NotNull] IEnumerable<IColumn> columns)
+            => "{"
+                + string.Join(
+                    ", ",
+                    columns.Select(p => "'" + p.Name + "'"))
+                + "}";
+
         /// <inheritdoc/>
         IEnumerable<IColumnMapping> IColumn.PropertyMappings
         {

src/EFCore.Relational/Metadata/Internal/ForeignKeyConstraint.cs

@@ -47,7 +47,7 @@ public ForeignKeyConstraint(
         ///     any release. You should only use it directly in your code with extreme caution and knowing that
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
-        public virtual SortedSet<IForeignKey> ForeignKeyMappings { get; } = new SortedSet<IForeignKey>(ForeignKeyComparer.Instance);
+        public virtual SortedSet<IForeignKey> MappedForeignKeys { get; } = new SortedSet<IForeignKey>(ForeignKeyComparer.Instance);
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -85,7 +85,7 @@ public ForeignKeyConstraint(
         public virtual ReferentialAction OnDeleteAction { get; set; }
 
         /// <inheritdoc />
-        IEnumerable<IForeignKey> IForeignKeyConstraint.MappedForeignKeys => ForeignKeyMappings;
+        IEnumerable<IForeignKey> IForeignKeyConstraint.MappedForeignKeys => MappedForeignKeys;
 
         /// <inheritdoc />
         ITable IForeignKeyConstraint.Table => Table;

src/EFCore.Relational/Metadata/Internal/ForeignKeyConstraintComparer.cs

@@ -35,7 +35,13 @@ private ForeignKeyConstraintComparer()
         /// </summary>
         public int Compare(IForeignKeyConstraint x, IForeignKeyConstraint y)
         {
-            var result = ColumnListComparer.Instance.Compare(x.Columns, y.Columns);
+            var result = StringComparer.Ordinal.Compare(x.Name, y.Name);
+            if (result != 0)
+            {
+                return result;
+            }
+
+            result = ColumnListComparer.Instance.Compare(x.Columns, y.Columns);
             if (result != 0)
             {
                 return result;
@@ -69,6 +75,7 @@ public bool Equals(IForeignKeyConstraint x, IForeignKeyConstraint y)
         public int GetHashCode(IForeignKeyConstraint obj)
         {
             var hashCode = new HashCode();
+            hashCode.Add(obj.Name);
             hashCode.Add(obj.Columns, ColumnListComparer.Instance);
             hashCode.Add(obj.PrincipalColumns, ColumnListComparer.Instance);
             hashCode.Add(obj.Table.Name);

src/EFCore.Relational/Metadata/Internal/ForeignKeyConstraintExtensions.cs

@@ -43,11 +43,11 @@ public static string ToDebugString(
                 .Append(" ")
                 .Append(foreignKey.Table.Name)
                 .Append(" ")
-                .Append(Format(foreignKey.Columns))
+                .Append(Column.Format(foreignKey.Columns))
                 .Append(" -> ")
                 .Append(foreignKey.PrincipalTable.Name)
                 .Append(" ")
-                .Append(Format(foreignKey.PrincipalColumns));
+                .Append(Column.Format(foreignKey.PrincipalColumns));
 
             if (foreignKey.OnDeleteAction != ReferentialAction.NoAction)
             {
@@ -64,12 +64,5 @@ public static string ToDebugString(
 
             return builder.ToString();
         }
-
-        private static string Format([NotNull] IEnumerable<IColumn> columns)
-        => "{"
-            + string.Join(
-                ", ",
-                columns.Select(p => "'" + p.Name + "'"))
-            + "}";
     }
 }