Be explicit about type mappings being available on the finalized model

Part of #15663
Fixes #14433

The `GetTypeMapping` and `GetRelationalTypeMapping` methods will throw if there isn't a type mapping annotated on the model. Model finalization ensures that this is true.

Find methods still exist for cases where they need to be called before the model is finalized, and also so as not to break when not needed. However, see #16177

src/EFCore.Cosmos/Query/Internal/ValueBufferFactoryFactory.cs

@@ -54,7 +54,7 @@ private static Expression CreateGetValueExpression(
             var storeName = property.GetCosmosPropertyName();
             if (storeName.Length == 0)
             {
-                var type = property.FindMapping()?.Converter?.ProviderClrType
+                var type = property.GetTypeMapping().Converter?.ProviderClrType
                            ?? property.ClrType;
 
                 Expression calculatedExpression = Expression.Default(type);
@@ -80,7 +80,7 @@ public static Expression CreateGetStoreValueExpression(Expression jObjectExpress
                                 Expression.Constant(storeName));
 
             var modelClrType = property.ClrType;
-            var converter = property.FindMapping().Converter;
+            var converter = property.GetTypeMapping().Converter;
             if (converter != null)
             {
                 var nullableExpression = valueExpression;

src/EFCore.Cosmos/Update/Internal/DocumentSource.cs

@@ -170,7 +170,7 @@ private static JToken ConvertPropertyValue(IProperty property, object value)
                 return null;
             }
 
-            var converter = property.FindMapping().Converter;
+            var converter = property.GetTypeMapping().Converter;
             if (converter != null)
             {
                 value = converter.ConvertToProvider(value);

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

@@ -521,8 +521,7 @@ protected virtual void GeneratePropertyAnnotations([NotNull] IProperty property,
         }
 
         private static ValueConverter FindValueConverter(IProperty property)
-            => property.FindMapping()?.Converter
-               ?? property.GetValueConverter();
+            => property.GetTypeMapping().Converter;
 
         /// <summary>
         ///     Generates code for <see cref="IKey" /> objects.

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

@@ -181,7 +181,7 @@ private static IEnumerable<IAnnotatable> GetAnnotatables(IEnumerable<MigrationOp
         protected virtual IEnumerable<string> GetNamespaces([NotNull] IModel model)
             => model.GetEntityTypes().SelectMany(
                     e => e.GetDeclaredProperties()
-                        .SelectMany(p => (p.FindMapping()?.Converter?.ProviderClrType ?? p.ClrType).GetNamespaces()))
+                        .SelectMany(p => (p.GetTypeMapping().Converter?.ProviderClrType ?? p.ClrType).GetNamespaces()))
                 .Concat(GetAnnotationNamespaces(GetAnnotatables(model)));
 
         private static IEnumerable<IAnnotatable> GetAnnotatables(IModel model)
@@ -264,7 +264,7 @@ private static IEnumerable<string> GetAnnotationNamespaces(IEnumerable<IAnnotata
         private static Type GetProviderType(IAnnotatable annotatable, Type valueType)
             => annotatable is IProperty property
                && valueType.UnwrapNullableType() == property.ClrType.UnwrapNullableType()
-                ? property.FindMapping()?.Converter?.ProviderClrType ?? valueType
+                ? property.GetTypeMapping().Converter?.ProviderClrType ?? valueType
                 : valueType;
     }
 }

src/EFCore.InMemory/Storage/Internal/InMemoryTable.cs

@@ -89,7 +89,7 @@ private static List<ValueComparer> GetStructuralComparers(IEnumerable<IProperty>
             => properties.Select(GetStructuralComparer).ToList();
 
         private static ValueComparer GetStructuralComparer(IProperty p)
-            => p.GetStructuralValueComparer() ?? p.FindMapping()?.StructuralComparer;
+            => p.GetStructuralValueComparer() ?? p.GetTypeMapping().StructuralComparer;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to

src/EFCore.InMemory/ValueGeneration/Internal/InMemoryValueGeneratorSelector.cs

@@ -57,6 +57,7 @@ public override ValueGenerator Select(IProperty property, IEntityType entityType
 
             return property.GetValueGeneratorFactory() == null
                    && property.ClrType.IsInteger()
+                   && property.ClrType.UnwrapNullableType() != typeof(char)
                 ? GetOrCreate(property)
                 : base.Select(property, entityType);
         }

src/EFCore.Relational/Extensions/RelationalPropertyExtensions.cs

@@ -397,13 +397,22 @@ public static void SetIsFixedLength([NotNull] this IConventionProperty property,
             => property.FindAnnotation(RelationalAnnotationNames.IsFixedLength)?.GetConfigurationSource();
 
         /// <summary>
-        ///     Returns the <see cref="RelationalTypeMapping" /> for the given property.
+        ///     Returns the <see cref="RelationalTypeMapping" /> for the given property on a finalized model.
+        /// </summary>
+        /// <param name="property"> The property. </param>
+        /// <returns> The type mapping. </returns>
+        [DebuggerStepThrough]
+        public static RelationalTypeMapping GetRelationalTypeMapping([NotNull] this IProperty property)
+            => (RelationalTypeMapping)property.GetTypeMapping();
+
+        /// <summary>
+        ///     Returns the <see cref="RelationalTypeMapping" /> for the given property on a finalized model.
         /// </summary>
         /// <param name="property"> The property. </param>
         /// <returns> The type mapping, or null if none was found. </returns>
         [DebuggerStepThrough]
         public static RelationalTypeMapping FindRelationalMapping([NotNull] this IProperty property)
-            => property[CoreAnnotationNames.TypeMapping] as RelationalTypeMapping;
+            => (RelationalTypeMapping)property.FindMapping();
 
         /// <summary>
         ///     <para>

src/EFCore.Relational/Infrastructure/RelationalModelValidator.cs

@@ -359,9 +359,9 @@ protected virtual void ValidateSharedColumnsCompatibility(
                     }
 
                     var currentTypeString = property.GetColumnType()
-                                            ?? property.FindRelationalMapping()?.StoreType;
+                                            ?? property.GetRelationalTypeMapping().StoreType;
                     var previousTypeString = duplicateProperty.GetColumnType()
-                                             ?? duplicateProperty.FindRelationalMapping()?.StoreType;
+                                             ?? duplicateProperty.GetRelationalTypeMapping().StoreType;
                     if (!string.Equals(currentTypeString, previousTypeString, StringComparison.OrdinalIgnoreCase))
                     {
                         throw new InvalidOperationException(

src/EFCore.Relational/Metadata/Conventions/RelationalValueGenerationConvention.cs

@@ -58,7 +58,7 @@ public virtual void ProcessPropertyAnnotationChanged(
         /// <param name="property"> The property. </param>
         /// <returns> The store value generation strategy to set for the given property. </returns>
         protected override ValueGenerated? GetValueGenerated(IConventionProperty property)
-            => GetValueGenerated((IProperty)property);
+            => GetValueGenerated(property);
 
         /// <summary>
         ///     Returns the store value generation strategy to set for the given property.

src/EFCore.Relational/Migrations/HistoryRepository.cs

@@ -105,7 +105,7 @@ private IModel EnsureModel()
                         x.ToTable(TableName, TableSchema);
                     });
 
-                _model = modelBuilder.Model;
+                _model = modelBuilder.FinalizeModel();
             }
 
             return _model;

src/EFCore.Relational/Migrations/Internal/MigrationsModelDiffer.cs

@@ -1788,8 +1788,8 @@ protected virtual void DiffData(
                             var targetValue = entry.GetCurrentValue(targetProperty);
                             var comparer = targetProperty.GetValueComparer() ??
                                            sourceProperty.GetValueComparer() ??
-                                           targetProperty.FindMapping()?.Comparer ??
-                                           sourceProperty.FindMapping()?.Comparer;
+                                           targetProperty.GetTypeMapping().Comparer ??
+                                           sourceProperty.GetTypeMapping().Comparer;
 
                             var modelValuesChanged
                                 = sourceProperty.ClrType.UnwrapNullableType() == targetProperty.ClrType.UnwrapNullableType()

src/EFCore.Relational/Query/Pipeline/RelationalProjectionBindingRemovingExpressionVisitor.cs

@@ -78,7 +78,7 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
                     return CreateGetValueExpression(
                         projectionIndex,
                         IsNullableProjection(projection),
-                        property.FindRelationalMapping(),
+                        property.GetRelationalTypeMapping(),
                         methodCallExpression.Type);
                 }
 

src/EFCore.Relational/Query/Pipeline/SqlExpressions/ColumnExpression.cs

@@ -14,7 +14,7 @@ namespace Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.SqlExpressions
     public class ColumnExpression : SqlExpression
     {
         internal ColumnExpression(IProperty property, TableExpressionBase table, bool nullable)
-            : this(property.GetColumnName(), table, property.ClrType, property.FindRelationalMapping(),
+            : this(property.GetColumnName(), table, property.ClrType, property.GetRelationalTypeMapping(),
                   nullable || property.IsNullable || property.DeclaringEntityType.BaseType != null)
         {
         }

src/EFCore.Relational/Storage/RelationalCommandBuilderExtensions.cs

@@ -186,7 +186,7 @@ public static IRelationalCommandBuilder AddParameter(
                 new TypeMappedRelationalParameter(
                     invariantName,
                     name,
-                    property.FindRelationalMapping(),
+                    property.GetRelationalTypeMapping(),
                     property.IsNullable));
         }
 
@@ -277,7 +277,7 @@ public static IRelationalCommandBuilder AddPropertyParameter(
                 new TypeMappedPropertyRelationalParameter(
                     invariantName,
                     name,
-                    property.FindRelationalMapping(),
+                    property.GetRelationalTypeMapping(),
                     property));
         }
 

src/EFCore.Relational/Storage/TypeMaterializationInfo.cs

@@ -78,7 +78,7 @@ public TypeMaterializationInfo(
 
             if (mapping == null)
             {
-                mapping = property?.FindRelationalMapping()
+                mapping = property?.GetRelationalTypeMapping()
                           ?? typeMappingSource?.GetMapping(modelClrType);
             }
 

src/EFCore.Sqlite.Core/Migrations/Internal/SqliteMigrationsAnnotationProvider.cs

@@ -84,7 +84,6 @@ public override IEnumerable<IAnnotation> For(IProperty property)
         }
 
         private static bool HasConverter(IProperty property)
-            => (property.FindMapping()?.Converter
-                ?? property.GetValueConverter()) != null;
+            => property.GetTypeMapping().Converter  != null;
     }
 }

src/EFCore/ChangeTracking/Internal/ChangeDetector.cs

@@ -198,7 +198,7 @@ private void LocalDetectChanges(InternalEntityEntry entry)
                     var current = entry[property];
                     var original = entry.GetOriginalValue(property);
 
-                    var comparer = property.GetValueComparer() ?? property.FindMapping()?.Comparer;
+                    var comparer = property.GetValueComparer() ?? property.GetTypeMapping().Comparer;
 
                     if (comparer == null)
                     {
@@ -253,7 +253,7 @@ private void DetectKeyChange(InternalEntityEntry entry, IProperty property)
                 var currentValue = entry[property];
 
                 var comparer = property.GetKeyValueComparer()
-                               ?? property.FindMapping()?.KeyComparer;
+                               ?? property.GetTypeMapping().KeyComparer;
 
                 // Note that mutation of a byte[] key is not supported or detected, but two different instances
                 // of byte[] with the same content must be detected as equal.

src/EFCore/ChangeTracking/Internal/CompositeValueFactory.cs

@@ -133,7 +133,7 @@ protected virtual bool TryCreateFromEntry(
         /// </summary>
         protected static IEqualityComparer<object[]> CreateEqualityComparer([NotNull] IReadOnlyList<IProperty> properties)
         {
-            var comparers = properties.Select(p => p.GetKeyValueComparer() ?? p.FindMapping()?.KeyComparer).ToList();
+            var comparers = properties.Select(p => p.GetKeyValueComparer() ?? p.GetTypeMapping().KeyComparer).ToList();
 
             return comparers.All(c => c != null)
                 ? new CompositeCustomComparer(comparers)

src/EFCore/ChangeTracking/Internal/InternalEntityEntry.cs

@@ -1184,7 +1184,7 @@ private void SetProperty(
         private static Func<object, object, bool> ValuesEqualFunc(IProperty property)
         {
             var comparer = property.GetValueComparer()
-                           ?? property.FindMapping()?.Comparer;
+                           ?? property.GetTypeMapping().Comparer;
 
             return comparer != null
                 ? (Func<object, object, bool>)((l, r) => comparer.Equals(l, r))

src/EFCore/ChangeTracking/Internal/NavigationFixer.cs

@@ -859,7 +859,7 @@ private static bool PrincipalValueEqualsDependentValue(
             object dependentValue,
             object principalValue)
             => (principalProperty.GetKeyValueComparer()
-                ?? principalProperty.FindMapping()?.KeyComparer)
+                ?? principalProperty.GetTypeMapping().KeyComparer)
                 ?.Equals(dependentValue, principalValue)
                 ?? StructuralComparisons.StructuralEqualityComparer.Equals(
                    dependentValue,

src/EFCore/ChangeTracking/Internal/OriginalValues.cs

@@ -107,7 +107,7 @@ public void AcceptChanges(InternalEntityEntry entry)
 
             private static object SnapshotValue(IProperty property, object value)
             {
-                var comparer = property.GetValueComparer() ?? property.FindMapping()?.Comparer;
+                var comparer = property.GetValueComparer() ?? property.GetTypeMapping().Comparer;
 
                 return comparer == null ? value : comparer.Snapshot(value);
             }

src/EFCore/ChangeTracking/Internal/OriginalValuesFactoryFactory.cs

@@ -39,6 +39,6 @@ protected override int GetPropertyCount(IEntityType entityType)
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
         protected override ValueComparer GetValueComparer(IProperty property)
-            => property.GetValueComparer() ?? property.FindMapping()?.Comparer;
+            => property.GetValueComparer() ?? property.GetTypeMapping().Comparer;
     }
 }

src/EFCore/ChangeTracking/Internal/RelationshipSnapshotFactoryFactory.cs

@@ -39,6 +39,6 @@ protected override int GetPropertyCount(IEntityType entityType)
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
         protected override ValueComparer GetValueComparer(IProperty property)
-            => property.GetKeyValueComparer() ?? property.FindMapping()?.KeyComparer;
+            => property.GetKeyValueComparer() ?? property.GetTypeMapping().KeyComparer;
     }
 }

src/EFCore/ChangeTracking/Internal/RelationshipsSnapshot.cs

@@ -49,7 +49,7 @@ private static object SnapshotValue(IPropertyBase propertyBase, object value)
             {
                 if (propertyBase is IProperty property)
                 {
-                    var comparer = property.GetKeyValueComparer() ?? property.FindMapping()?.KeyComparer;
+                    var comparer = property.GetKeyValueComparer() ?? property.GetTypeMapping().KeyComparer;
 
                     if (comparer != null)
                     {

src/EFCore/ChangeTracking/Internal/SidecarValues.cs

@@ -53,7 +53,7 @@ public void SetValue(IProperty property, object value, int index)
 
             private static object SnapshotValue(IProperty property, object value)
             {
-                var comparer = property.GetValueComparer() ?? property.FindMapping()?.Comparer;
+                var comparer = property.GetValueComparer() ?? property.GetTypeMapping().Comparer;
 
                 return comparer == null ? value : comparer.Snapshot(value);
             }

src/EFCore/ChangeTracking/Internal/SidecarValuesFactoryFactory.cs

@@ -39,6 +39,6 @@ protected override int GetPropertyCount(IEntityType entityType)
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
         protected override ValueComparer GetValueComparer(IProperty property)
-            => property.GetValueComparer() ?? property.FindMapping()?.Comparer;
+            => property.GetValueComparer() ?? property.GetTypeMapping().Comparer;
     }
 }

src/EFCore/ChangeTracking/Internal/SimplePrincipalKeyValueFactory.cs

@@ -35,7 +35,7 @@ public SimplePrincipalKeyValueFactory([NotNull] IProperty property)
             _propertyAccessors = _property.GetPropertyAccessors();
 
             var comparer = property.GetKeyValueComparer()
-                           ?? property.FindMapping()?.KeyComparer;
+                           ?? property.GetTypeMapping().KeyComparer;
 
             EqualityComparer
                 = comparer != null

src/EFCore/ChangeTracking/Internal/StateManager.cs

@@ -1078,7 +1078,7 @@ private static bool KeysEqual(InternalEntityEntry entry, IForeignKey fk, Interna
 
         private static bool KeyValuesEqual(IProperty property, object value, object currentValue)
             => (property.GetKeyValueComparer()
-                ?? property.FindMapping()?.KeyComparer)
+                ?? property.GetTypeMapping().KeyComparer)
                ?.Equals(currentValue, value)
                ?? Equals(currentValue, value);
 

src/EFCore/Extensions/PropertyExtensions.cs

@@ -3,9 +3,11 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.ChangeTracking;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Internal;
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
@@ -22,6 +24,25 @@ namespace Microsoft.EntityFrameworkCore
     /// </summary>
     public static class PropertyExtensions
     {
+        /// <summary>
+        ///     Returns the <see cref="CoreTypeMapping" /> for the given property from a finalized model.
+        /// </summary>
+        /// <param name="property"> The property. </param>
+        /// <returns> The type mapping. </returns>
+        public static CoreTypeMapping GetTypeMapping(
+            [NotNull] this IProperty property)
+        {
+            var mapping = (CoreTypeMapping)property[CoreAnnotationNames.TypeMapping];
+
+            if (mapping == null)
+            {
+                throw new InvalidOperationException(
+                    CoreStrings.ModelNotFinalized(nameof(GetTypeMapping)));
+            }
+
+            return mapping;
+        }
+
         /// <summary>
         ///     Returns the <see cref="CoreTypeMapping" /> for the given property.
         /// </summary>

src/EFCore/Metadata/Internal/ClrPropertyGetterFactory.cs

@@ -93,7 +93,7 @@ protected override IClrPropertyGetter CreateGeneric<TEntity, TValue, TNonNullabl
             {
                 var property = propertyBase as IProperty;
                 var comparer = property?.GetValueComparer()
-                               ?? property?.FindMapping()?.Comparer
+                               ?? property?.GetTypeMapping().Comparer
                                ?? (ValueComparer)Activator.CreateInstance(
                                    typeof(ValueComparer<>).MakeGenericType(typeof(TValue)),
                                    new object[]

src/EFCore/Metadata/Internal/EntityType.cs

@@ -2355,7 +2355,7 @@ public virtual IEnumerable<IDictionary<string, object>> GetSeedData(bool provide
                     {
                         if (propertyBase is IProperty property)
                         {
-                            valueConverter = property.FindMapping()?.Converter
+                            valueConverter = property.GetTypeMapping().Converter
                                              ?? property.GetValueConverter();
                         }
 

src/EFCore/Metadata/Internal/IndexedPropertyGetterFactory.cs

@@ -54,7 +54,7 @@ protected override IClrPropertyGetter CreateGeneric<TEntity, TValue, TNonNullabl
             var comparer = typeof(TValue).IsNullableType()
                 ? null
                 : property?.GetValueComparer()
-                  ?? property?.FindMapping()?.Comparer
+                  ?? property?.GetTypeMapping().Comparer
                   ?? (ValueComparer)Activator.CreateInstance(
                       typeof(ValueComparer<>).MakeGenericType(typeof(TValue)),
                       new object[]