From 761b6e0068f91aeffb078f26b3f7400b08374faa Mon Sep 17 00:00:00 2001
From: 28810 <28810@YEXIANGQIN>
Date: Thu, 27 Feb 2020 12:54:43 +0800
Subject: [PATCH] =?UTF-8?q?-=20=E4=BF=AE=E5=A4=8D=20DbSet.Where=20?=
 =?UTF-8?q?=E8=A1=A8=E8=BE=BE=E5=BC=8F=E8=A7=A3=E6=9E=90=E6=8A=A5=E9=94=99?=
 =?UTF-8?q?=E7=9A=84=E9=97=AE=E9=A2=98=EF=BC=9B#216?=
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---
 FreeSql.Tests/FreeSql.Tests/UnitTest3.cs | 32 ++++++++++++++++++++++++
 FreeSql/Internal/CommonExpression.cs     | 26 +++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/FreeSql.Tests/FreeSql.Tests/UnitTest3.cs b/FreeSql.Tests/FreeSql.Tests/UnitTest3.cs
index 1d90c5595..8d1d11fe3 100644
--- a/FreeSql.Tests/FreeSql.Tests/UnitTest3.cs
+++ b/FreeSql.Tests/FreeSql.Tests/UnitTest3.cs
@@ -22,9 +22,41 @@ namespace FreeSql.Tests
     public class UnitTest3
     {
 
+        public class Song23
+        {
+            public long Id { get; set; }
+            public string Name { get; set; }
+        }
+
+        public class Author23
+        {
+            public long Id { get; set; }
+            public long SongId { get; set; }
+            public string Name { get; set; }
+        }
+
+        public class TestDbContext : DbContext
+        {
+            public TestDbContext(IFreeSql orm) : base(orm, null)
+            {
+            }
+            public DbSet<Song23> Songs { get; set; }
+            public DbSet<Author23> Authors { get; set; }
+        }
+
         [Fact]
         public void Test03()
         {
+            var context = new TestDbContext(g.sqlite);
+
+            var sql = context.Songs
+                .Where(a =>
+                    context.Authors
+                        //.Select  //加上这句就不报错，不加上报 variable 'a' of type 'Song' referenced from scope '', but it is not defined
+                        .Where(b => b.SongId == a.Id)
+                        .Any())
+                .ToSql(a => a.Name);
+
             //using (var conn = new SqlConnection("Data Source=.;Integrated Security=True;Initial Catalog=webchat-abc;Pooling=true;Max Pool Size=13"))
             //{
             //    conn.Open();
diff --git a/FreeSql/Internal/CommonExpression.cs b/FreeSql/Internal/CommonExpression.cs
index 9a9b7a86d..3dc16e122 100644
--- a/FreeSql/Internal/CommonExpression.cs
+++ b/FreeSql/Internal/CommonExpression.cs
@@ -771,6 +771,32 @@ public string ExpressionLambdaToSql(Expression exp, ExpTSC tsc)
                                                     }
                                                 }
                                             }
+                                            if (new[] { "Where", "WhereIf" }.Contains(exp3tmpCall.Method.Name) && exp3tmpCall.Object != null)
+                                            {
+                                                //这段特别兼容 DbSet.Where 表达式解析 #216
+                                                var exp3tmpTestCall = Expression.Call(exp3tmpCall.Object, exp3tmpCall.Method, exp3tmpCall.Arguments.Select(a =>
+                                                {
+                                                    var a2 = a;
+                                                    if (a2.NodeType == ExpressionType.Quote) a2 = (a as UnaryExpression)?.Operand;
+                                                    if (a2?.NodeType == ExpressionType.Lambda)
+                                                    {
+                                                        var alambda = a2 as LambdaExpression;
+                                                        if (alambda.ReturnType == typeof(bool))
+                                                            return Expression.Constant(null, a.Type);// Expression.Lambda(Expression.Constant(true), alambda.Parameters);
+                                                    }
+                                                    return a;
+                                                    //if (a.Type == typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(exp3tmp.Type.GetGenericArguments()[0], typeof(bool))))
+                                                    //    return Expression.Lambda(Expression.Constant(true), 
+                                                }).ToArray());
+                                                fsql = Expression.Lambda(exp3tmpTestCall).Compile().DynamicInvoke();
+                                                var fsqlFindMethod = fsql.GetType().GetMethod(exp3tmpCall.Method.Name, exp3tmpCall.Arguments.Select(a => a.Type).ToArray());
+                                                if (fsqlFindMethod == null)
+                                                    throw new Exception($"无法解析表达式方法 {exp3tmpCall.Method.Name}");
+                                                var exp3StackOld = exp3Stack;
+                                                exp3Stack = new Stack<Expression>();
+                                                exp3Stack.Push(Expression.Call(Expression.Constant(fsql), fsqlFindMethod, exp3tmpCall.Arguments));
+                                                while (exp3StackOld.Any()) exp3Stack.Push(exp3StackOld.Pop());
+                                            }
                                         }
                                         if (fsql == null) fsql = Expression.Lambda(exp3tmp).Compile().DynamicInvoke();
                                         fsqlType = fsql?.GetType();