修复优化当表达式内嵌使用属性的情况下出现：Cannot use multiple context instances within a single query execution. Ensure the query use a single context instance.的错误

Author: xuejmnet

samples/Sample.MySql/Controllers/WeatherForecastController.cs

@@ -22,18 +22,37 @@ public class abc
         public string name { get; set; }
         public int count { get; set; }
     }
+
+    public class ABC
+    {
+        private readonly DefaultShardingDbContext _defaultTableDbContext;
+
+        public ABC(DefaultShardingDbContext defaultTableDbContext)
+        {
+            _defaultTableDbContext = defaultTableDbContext;
+        }
+
+        public IQueryable<SysTest> GetAll()
+        {
+            return _defaultTableDbContext.Set<SysTest>();
+        }
+
+        public virtual IQueryable<SysTest> Select => this.GetAll();
+    }
     [ApiController]
     [Route("[controller]/[action]")]
     public class WeatherForecastController : ControllerBase
     {
 
         private readonly DefaultShardingDbContext _defaultTableDbContext;
         private readonly IShardingRuntimeContext _shardingRuntimeContext;
+        private readonly ABC _abc;
 
         public WeatherForecastController(DefaultShardingDbContext defaultTableDbContext,IShardingRuntimeContext shardingRuntimeContext)
         {
             _defaultTableDbContext = defaultTableDbContext;
             _shardingRuntimeContext = shardingRuntimeContext;
+            _abc=new ABC(_defaultTableDbContext);
         }
 
         public IQueryable<SysTest> GetAll()
@@ -86,7 +105,12 @@ public async Task<IActionResult> Get()
             // var firstOrDefault = _defaultTableDbContext.Set<SysUserMod>().FromSqlRaw($"select * from {nameof(SysUserMod)}").FirstOrDefault();
 
             var sysUserMods1 = _defaultTableDbContext.Set<SysTest>()
+                .Select(o => new ssss(){ Id = o.Id, C = _abc.Select.Count(x => x.Id == o.Id) }).ToList();
+            var sysUserMods2 = _defaultTableDbContext.Set<SysTest>()
                 .Select(o => new ssss(){ Id = o.Id, C = GetAll().Count(x => x.Id == o.Id) }).ToList();
+            var sysTests = GetAll();
+            var sysUserMods3 = _defaultTableDbContext.Set<SysTest>()
+                .Select(o => new ssss(){ Id = o.Id, C = sysTests.Count(x => x.Id == o.Id) }).ToList();
             var resultX = await _defaultTableDbContext.Set<SysUserMod>()
                     .Where(o => o.Id == "2" || o.Id == "3").FirstOrDefaultAsync();
                 var resultY = await _defaultTableDbContext.Set<SysUserMod>().FirstOrDefaultAsync(o => o.Id == "2" || o.Id == "3");

src/ShardingCore/Extensions/CommonExtension.cs

@@ -176,7 +176,7 @@ public static bool IsMemberQueryable(this MemberExpression memberExpression)
         {
             if (memberExpression == null)
                 throw new ArgumentNullException(nameof(memberExpression));
-            return (memberExpression.Type.FullName?.StartsWith("System.Linq.IQueryable`1") ?? false) || typeof(DbContext).IsAssignableFrom(memberExpression.Type);
+            return (memberExpression.Type.FullName?.StartsWith("System.Linq.IQueryable`1") ?? false) ||typeof(IQueryable).IsAssignableFrom(memberExpression.Type) || typeof(DbContext).IsAssignableFrom(memberExpression.Type);
         }
 
         public static Type GetSequenceType(this Type type)

src/ShardingCore/Sharding/Visitors/DbContextReplaceQueryableVisitor.cs

@@ -18,7 +18,7 @@ namespace ShardingCore.Core.Internal.Visitors
     * @Email: 326308290@qq.com
     */
 
-    internal class DbContextInnerMemberReferenceReplaceQueryableVisitor : ExpressionVisitor
+    internal class DbContextInnerMemberReferenceReplaceQueryableVisitor : ShardingExpressionVisitor
     {
         private readonly DbContext _dbContext;
         protected bool RootIsVisit = false;
@@ -28,50 +28,29 @@ public DbContextInnerMemberReferenceReplaceQueryableVisitor(DbContext dbContext)
             _dbContext = dbContext;
         }
 
+        // public override Expression Visit(Expression node)
+        // {
+        //     Console.WriteLine("1");
+        //     return base.Visit(node);
+        // }
+
         protected override Expression VisitMember
             (MemberExpression memberExpression)
         {
             // Recurse down to see if we can simplify...
-            //if (memberExpression.IsMemberQueryable()) //2x,3x 路由 单元测试 分表和不分表
-            //{
-            var expression = Visit(memberExpression.Expression);
-
-            // If we've ended up with a constant, and it's a property or a field,
-            // we can simplify ourselves to a constant
-            if (expression is ConstantExpression constantExpression)
+            if (memberExpression.IsMemberQueryable()) //2x,3x 路由 单元测试 分表和不分表
             {
-                object container = constantExpression.Value;
-                var member = memberExpression.Member;
-                if (member is FieldInfo fieldInfo)
+                var expressionValue = GetExpressionValue(memberExpression);
+                if (expressionValue is IQueryable queryable)
                 {
-                    object value = fieldInfo.GetValue(container);
-                    if (value is IQueryable queryable)
-                    {
-                        return ReplaceMemberExpression(queryable);
-                    }
-
-                    if (value is DbContext dbContext)
-                    {
-                        return ReplaceMemberExpression(dbContext);
-                    }
-                    //return Expression.Constant(value);
+                    return ReplaceMemberExpression(queryable);
                 }
 
-                if (member is PropertyInfo propertyInfo)
+                if (expressionValue is DbContext dbContext)
                 {
-                    object value = propertyInfo.GetValue(container, null);
-                    if (value is IQueryable queryable)
-                    {
-                        return ReplaceMemberExpression(queryable);
-                    }
-
-                    if (value is DbContext dbContext)
-                    {
-                        return ReplaceMemberExpression(dbContext);
-                    }
+                    return ReplaceMemberExpression(dbContext);
                 }
-            }
-            //}
+           }
 
             return base.VisitMember(memberExpression);
         }