Fix to #28816 - Json: add support for Sqlite provider

Adding support for Sqlite.

Limitation:
When accessing element of a JSON array we can only use constant values. Unlike Sql Server which supports parameters, columns or even arbitrary expressions.

Fixes #28816

src/EFCore.Sqlite.Core/Metadata/Internal/SqliteAnnotationProvider.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.EntityFrameworkCore.Metadata.Internal;
 using Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal;
 
 namespace Microsoft.EntityFrameworkCore.Sqlite.Metadata.Internal;
@@ -47,24 +48,28 @@ public override IEnumerable<IAnnotation> For(IRelationalModel model, bool design
     /// </summary>
     public override IEnumerable<IAnnotation> For(IColumn column, bool designTime)
     {
-        // Model validation ensures that these facets are the same on all mapped properties
-        var property = column.PropertyMappings.First().Property;
-        // Only return auto increment for integer single column primary key
-        var primaryKey = property.DeclaringEntityType.FindPrimaryKey();
-        if (primaryKey != null
-            && primaryKey.Properties.Count == 1
-            && primaryKey.Properties[0] == property
-            && property.ValueGenerated == ValueGenerated.OnAdd
-            && property.ClrType.UnwrapNullableType().IsInteger()
-            && !HasConverter(property))
+        // JSON columns have no property mappings so all annotations that rely on property mappings should be skipped for them
+        if (column is not JsonColumn)
         {
-            yield return new Annotation(SqliteAnnotationNames.Autoincrement, true);
-        }
+            // Model validation ensures that these facets are the same on all mapped properties
+            var property = column.PropertyMappings.First().Property;
+            // Only return auto increment for integer single column primary key
+            var primaryKey = property.DeclaringEntityType.FindPrimaryKey();
+            if (primaryKey != null
+                && primaryKey.Properties.Count == 1
+                && primaryKey.Properties[0] == property
+                && property.ValueGenerated == ValueGenerated.OnAdd
+                && property.ClrType.UnwrapNullableType().IsInteger()
+                && !HasConverter(property))
+            {
+                yield return new Annotation(SqliteAnnotationNames.Autoincrement, true);
+            }
 
-        var srid = property.GetSrid();
-        if (srid != null)
-        {
-            yield return new Annotation(SqliteAnnotationNames.Srid, srid);
+            var srid = property.GetSrid();
+            if (srid != null)
+            {
+                yield return new Annotation(SqliteAnnotationNames.Srid, srid);
+            }
         }
     }
 

src/EFCore.Sqlite.Core/Properties/SqliteStrings.resx

@@ -198,6 +198,9 @@
   <data name="MigrationScriptGenerationNotSupported" xml:space="preserve">
     <value>Generating idempotent scripts for migrations is not currently supported for SQLite. See http://go.microsoft.com/fwlink/?LinkId=723262 for more information and examples.</value>
   </data>
+  <data name="NonConstantJsonArrayIndexNotSupported" xml:space="preserve">
+    <value>JSON array element can only be accessed using constant value for the array index. Non-constant value is being used in PATH for JSON column '{jsonColumnName}'.</value>
+  </data>
   <data name="OrderByNotSupported" xml:space="preserve">
     <value>SQLite does not support expressions of type '{type}' in ORDER BY clauses. Convert the values to a supported type, or use LINQ to Objects to order the results on the client side.</value>
   </data>

src/EFCore.Sqlite.Core/Query/Internal/SqliteQuerySqlGenerator.cs

@@ -117,4 +117,70 @@ private Expression VisitRegexp(RegexpExpression regexpExpression)
 
         return regexpExpression;
     }
+
+    /// <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>
+    protected override Expression VisitJsonScalar(JsonScalarExpression jsonScalarExpression)
+    {
+        if (jsonScalarExpression.Path.Count == 1
+            && jsonScalarExpression.Path[0].ToString() == "$")
+        {
+            Visit(jsonScalarExpression.JsonColumn);
+
+            return jsonScalarExpression;
+        }
+
+        // TODO: need casts?
+        Sql.Append("json_extract(");
+
+        Visit(jsonScalarExpression.JsonColumn);
+
+        Sql.Append(",'");
+        foreach (var pathSegment in jsonScalarExpression.Path)
+        {
+            if (pathSegment.PropertyName != null)
+            {
+                Sql.Append((pathSegment.PropertyName == "$" ? "" : ".") + pathSegment.PropertyName);
+            }
+
+            if (pathSegment.ArrayIndex != null)
+            {
+                Sql.Append("[");
+
+                if (pathSegment.ArrayIndex is SqlConstantExpression)
+                {
+                    Visit(pathSegment.ArrayIndex);
+                }
+                else
+                {
+                    Sql.Append("' + ");
+                    Visit(pathSegment.ArrayIndex);
+                    Sql.Append(" + '");
+                    //throw new InvalidOperationException("TODO");
+                    //Sql.Append("' + CAST(");
+                    //Visit(pathSegment.ArrayIndex);
+                    //Sql.Append(" AS ");
+                    //Sql.Append(_typeMappingSource.GetMapping(typeof(string)).StoreType);
+                    //Sql.Append(") + '");
+                }
+
+                Sql.Append("]");
+            }
+        }
+
+        Sql.Append("')");
+
+        //if (jsonScalarExpression.TypeMapping is not SqlServerJsonTypeMapping and not StringTypeMapping)
+        //{
+        //    Sql.Append(" AS ");
+        //    Sql.Append(jsonScalarExpression.TypeMapping!.StoreType);
+        //    Sql.Append(")");
+        //}
+
+        return jsonScalarExpression;
+    }
 }

src/EFCore.Sqlite.Core/Query/Internal/SqliteQueryTranslationPostprocessor.cs

@@ -14,7 +14,7 @@ namespace Microsoft.EntityFrameworkCore.Sqlite.Query.Internal;
 /// </summary>
 public class SqliteQueryTranslationPostprocessor : RelationalQueryTranslationPostprocessor
 {
-    private readonly ApplyValidatingVisitor _applyValidator = new();
+    private readonly ValidatingVisitor _validator = new();
 
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -39,12 +39,12 @@ public SqliteQueryTranslationPostprocessor(
     public override Expression Process(Expression query)
     {
         var result = base.Process(query);
-        _applyValidator.Visit(result);
+        _validator.Visit(result);
 
         return result;
     }
 
-    private sealed class ApplyValidatingVisitor : ExpressionVisitor
+    private sealed class ValidatingVisitor : ExpressionVisitor
     {
         protected override Expression VisitExtension(Expression extensionExpression)
         {
@@ -62,6 +62,14 @@ protected override Expression VisitExtension(Expression extensionExpression)
                 throw new InvalidOperationException(SqliteStrings.ApplyNotSupported);
             }
 
+            if (extensionExpression is JsonScalarExpression jsonScalarExpression
+                && jsonScalarExpression.Path.Any(x => x.ArrayIndex is not null and not SqlConstantExpression))
+            {
+                throw new InvalidOperationException(
+                    SqliteStrings.NonConstantJsonArrayIndexNotSupported(
+                        jsonScalarExpression.JsonColumn.Name));
+            }
+
             return base.VisitExtension(extensionExpression);
         }
     }

src/EFCore.Sqlite.Core/Storage/Internal/SqliteJsonTypeMapping.cs

@@ -0,0 +1,95 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Data;
+using System.Text.Json;
+
+namespace Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal;
+
+/// <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 class SqliteJsonTypeMapping : JsonTypeMapping
+{
+    private static readonly MethodInfo _getStringMethod
+        = typeof(DbDataReader).GetRuntimeMethod(nameof(DbDataReader.GetString), new[] { typeof(int) })!;
+
+    private static readonly MethodInfo _jsonDocumentParseMethod
+        = typeof(JsonDocument).GetRuntimeMethod(nameof(JsonDocument.Parse), new[] { typeof(string), typeof(JsonDocumentOptions) })!;
+
+    private static readonly MemberInfo _jsonDocumentRootElementMember
+        = typeof(JsonDocument).GetRuntimeProperty(nameof(JsonDocument.RootElement))!;
+
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="SqliteJsonTypeMapping" /> class.
+    /// </summary>
+    /// <param name="storeType">The name of the database type.</param>
+    public SqliteJsonTypeMapping(string storeType)
+        : base(storeType, typeof(JsonElement), System.Data.DbType.String)
+    {
+    }
+
+    /// <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>
+    protected SqliteJsonTypeMapping(RelationalTypeMappingParameters parameters)
+        : base(parameters)
+    {
+    }
+
+    /// <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 override MethodInfo GetDataReaderMethod()
+        => _getStringMethod;
+
+    /// <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 override Expression CustomizeDataReaderExpression(Expression expression)
+        => Expression.MakeMemberAccess(
+            Expression.Call(
+                _jsonDocumentParseMethod,
+                expression,
+                Expression.Default(typeof(JsonDocumentOptions))),
+            _jsonDocumentRootElementMember);
+
+    /// <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>
+    protected override string GenerateNonNullSqlLiteral(object value)
+        => $"'{EscapeSqlLiteral(JsonSerializer.Serialize(value))}'";
+
+    /// <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>
+    protected virtual string EscapeSqlLiteral(string literal)
+        => literal.Replace("'", "''");
+
+    /// <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>
+    protected override RelationalTypeMapping Clone(RelationalTypeMappingParameters parameters)
+        => new SqliteJsonTypeMapping(parameters);
+}

src/EFCore.Sqlite.Core/Storage/Internal/SqliteTypeMappingSource.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Text.Json;
+
 namespace Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal;
 
 /// <summary>
@@ -80,7 +82,8 @@ private static readonly HashSet<string> SpatialiteTypes
         { typeof(decimal), new SqliteDecimalTypeMapping(TextTypeName) },
         { typeof(double), Real },
         { typeof(float), new FloatTypeMapping(RealTypeName) },
-        { typeof(Guid), new SqliteGuidTypeMapping(TextTypeName) }
+        { typeof(Guid), new SqliteGuidTypeMapping(TextTypeName) },
+        { typeof(JsonElement), new SqliteJsonTypeMapping(TextTypeName) }
     };
 
     private readonly Dictionary<string, RelationalTypeMapping> _storeTypeMappings = new(StringComparer.OrdinalIgnoreCase)