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266
Extensions/FreeSql.Extensions.Linq/QueryableProvider.cs
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266
Extensions/FreeSql.Extensions.Linq/QueryableProvider.cs
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using FreeSql.Internal;
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using FreeSql.Internal.CommonProvider;
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using FreeSql.Internal.Model;
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Linq;
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using System.Linq.Expressions;
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using System.Reflection;
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using System.Text;
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namespace FreeSql.Extensions.Linq
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{
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class QueryableProvider<TCurrent, TSource> : IQueryable<TCurrent>, IOrderedQueryable<TCurrent> where TSource : class
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{
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Expression _expression;
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IQueryProvider _provider;
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internal Select1Provider<TSource> _select;
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public QueryableProvider(Select1Provider<TSource> select)
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{
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_select = select;
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_expression = Expression.Constant(this);
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_provider = new QueryProvider<TCurrent, TSource>(_select, _expression);
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}
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public QueryableProvider(Expression expression, IQueryProvider provider, Select1Provider<TSource> select)
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{
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_select = select;
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_expression = expression;
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_provider = provider;
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}
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public IEnumerator<TCurrent> GetEnumerator()
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{
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var result = _provider.Execute<List<TCurrent>>(_expression);
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if (result == null)
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yield break;
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foreach (var item in result)
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{
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yield return item;
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}
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}
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IEnumerator IEnumerable.GetEnumerator()
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{
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return (IEnumerator)GetEnumerator();
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}
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public Type ElementType => typeof(QueryableProvider<TCurrent, TSource>);
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public Expression Expression => _expression;
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public IQueryProvider Provider => _provider;
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}
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class QueryProvider<TCurrent, TSource> : IQueryProvider where TSource : class
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{
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Select1Provider<TSource> _select;
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Expression _oldExpression;
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public QueryProvider(Select1Provider<TSource> select, Expression oldExpression)
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{
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_select = select;
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_oldExpression = oldExpression;
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}
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public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
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{
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ExecuteExp(expression, null, false);
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if (typeof(TElement) != typeof(TCurrent))
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return new QueryableProvider<TElement, TSource>(expression, new QueryProvider<TElement, TSource>(_select, expression), _select);
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_oldExpression = expression;
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return new QueryableProvider<TElement, TSource>(expression, this, _select);
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}
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public IQueryable CreateQuery(Expression expression) => throw new NotImplementedException();
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public TResult Execute<TResult>(Expression expression)
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{
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return (TResult)ExecuteExp(expression, typeof(TResult), _oldExpression == expression);
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}
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public object Execute(Expression expression) => throw new NotImplementedException();
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public object ExecuteExp(Expression expression, Type tresult, bool isProcessed)
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{
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var callExp = expression as MethodCallExpression;
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var isfirst = false;
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if (callExp != null && isProcessed == false)
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{
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object throwCallExp(string message) => throw new Exception($"解析失败 {callExp.Method.Name} {message}，提示：可以使用扩展方法 IQueryable.RestoreToSelect() 还原为 ISelect 再查询");
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if (callExp.Method.DeclaringType != typeof(Queryable)) return throwCallExp($"必须属于 System.Linq.Queryable");
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object tplMaxMinAvgSum(string method)
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{
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if (callExp.Arguments.Count == 2)
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{
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var avgParam = (callExp.Arguments[1] as UnaryExpression)?.Operand as LambdaExpression;
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return Utils.GetDataReaderValue(tresult,
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_select.GetType().GetMethod(method).MakeGenericMethod(avgParam.ReturnType).Invoke(_select, new object[] { avgParam }));
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}
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return throwCallExp($" 不支持 {callExp.Arguments.Count}个参数的方法");
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}
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object tplOrderBy(string method, bool isDescending)
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{
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if (callExp.Arguments.Count == 2)
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{
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var arg1 = (callExp.Arguments[1] as UnaryExpression)?.Operand as LambdaExpression;
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_select.OrderByReflection(arg1, isDescending);
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return tresult.CreateInstanceGetDefaultValue();
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}
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return throwCallExp($" 不支持 {callExp.Arguments.Count}个参数的方法");
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}
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switch (callExp.Method.Name)
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{
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case "Any":
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if (callExp.Arguments.Count == 2) _select.InternalWhere(callExp.Arguments[1]);
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return _select.Any();
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case "AsQueryable":
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break;
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case "Max": return tplMaxMinAvgSum("Max");
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case "Min": return tplMaxMinAvgSum("Min");
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case "Sum": return tplMaxMinAvgSum("Sum");
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case "Average": return tplMaxMinAvgSum("Avg");
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case "Concat":
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return throwCallExp(CoreStrings.Not_Support);
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case "Contains":
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if (callExp.Arguments.Count == 2)
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{
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var dywhere = callExp.Arguments[1].GetConstExprValue();
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if (dywhere == null) return throwCallExp($" 参数值不能为 null");
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_select.WhereDynamic(dywhere);
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return _select.Any();
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}
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return throwCallExp($" 不支持 {callExp.Arguments.Count}个参数的方法");
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case "Count":
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if (callExp.Arguments.Count == 2) _select.InternalWhere(callExp.Arguments[1]);
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return Utils.GetDataReaderValue(tresult, _select.Count());
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case "Distinct":
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if (callExp.Arguments.Count == 1)
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{
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_select.Distinct();
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break;
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}
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return throwCallExp(CoreStrings.Not_Support);
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case "ElementAt":
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case "ElementAtOrDefault":
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_select.Offset((int)callExp.Arguments[1].GetConstExprValue());
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_select.Limit(1);
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isfirst = true;
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break;
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case "First":
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case "FirstOrDefault":
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case "Single":
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case "SingleOrDefault":
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if (callExp.Arguments.Count == 2) _select.InternalWhere(callExp.Arguments[1]);
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_select.Limit(1);
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isfirst = true;
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break;
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case "OrderBy":
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tplOrderBy("OrderByReflection", false);
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break;
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case "OrderByDescending":
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tplOrderBy("OrderByReflection", true);
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break;
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case "ThenBy":
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tplOrderBy("OrderByReflection", false);
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break;
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case "ThenByDescending":
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tplOrderBy("OrderByReflection", true);
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break;
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case "Where":
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var whereParam = (callExp.Arguments[1] as UnaryExpression)?.Operand as LambdaExpression;
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if (whereParam.Parameters.Count == 1)
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{
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_select.InternalWhere(whereParam);
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break;
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}
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return throwCallExp(CoreStrings.Not_Support);
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case "Skip":
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_select.Offset((int)callExp.Arguments[1].GetConstExprValue());
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break;
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case "Take":
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_select.Limit((int)callExp.Arguments[1].GetConstExprValue());
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break;
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case "ToList":
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if (callExp.Arguments.Count == 1)
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return _select.ToList();
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return throwCallExp(CoreStrings.Not_Support);
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case "Select":
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var selectParam = (callExp.Arguments[1] as UnaryExpression)?.Operand as LambdaExpression;
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if (selectParam.Parameters.Count == 1)
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{
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_select._selectExpression = selectParam;
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break;
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}
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return throwCallExp(CoreStrings.Not_Support);
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case "Join":
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if (callExp.Arguments.Count == 5)
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{
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var arg2 = (callExp.Arguments[2] as UnaryExpression)?.Operand as LambdaExpression;
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var arg3 = (callExp.Arguments[3] as UnaryExpression)?.Operand as LambdaExpression;
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var arg4 = (callExp.Arguments[4] as UnaryExpression)?.Operand as LambdaExpression;
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FreeSqlExtensionsLinqSql.InternalJoin2(_select, arg2, arg3, arg4);
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_select._selectExpression = arg4.Body;
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break;
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}
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return throwCallExp($" 不支持 {callExp.Arguments.Count}个参数的方法");
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case "GroupJoin":
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if (callExp.Arguments.Count == 5)
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{
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var arg2 = (callExp.Arguments[2] as UnaryExpression)?.Operand as LambdaExpression;
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var arg3 = (callExp.Arguments[3] as UnaryExpression)?.Operand as LambdaExpression;
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var arg4 = (callExp.Arguments[4] as UnaryExpression)?.Operand as LambdaExpression;
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FreeSqlExtensionsLinqSql.InternalJoin2(_select, arg2, arg3, arg4);
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_select._selectExpression = arg4.Body;
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break;
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}
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return throwCallExp($" 不支持 {callExp.Arguments.Count}个参数的方法");
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case "SelectMany":
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if (callExp.Arguments.Count == 3)
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{
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var arg1 = (callExp.Arguments[1] as UnaryExpression)?.Operand as LambdaExpression;
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var arg2 = (callExp.Arguments[2] as UnaryExpression)?.Operand as LambdaExpression;
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FreeSqlExtensionsLinqSql.InternalSelectMany2(_select, arg1, arg2);
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_select._selectExpression = arg2.Body;
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break;
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}
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return throwCallExp($" 不支持 {callExp.Arguments.Count}个参数的方法");
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case "DefaultIfEmpty":
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break;
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case "Last":
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case "LastOrDefault":
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return throwCallExp(CoreStrings.Not_Support);
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case "GroupBy":
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return throwCallExp(CoreStrings.Not_Support);
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default:
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return throwCallExp(CoreStrings.Not_Support);
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}
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}
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if (tresult == null) return null;
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if (isfirst)
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{
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_select.Limit(1);
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if (_select._selectExpression != null)
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return _select.InternalToList<TCurrent>(_select._selectExpression).FirstOrDefault();
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return _select.ToList().FirstOrDefault();
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}
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if (_select._selectExpression != null)
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return _select.InternalToList<TCurrent>(_select._selectExpression);
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return _select.ToList();
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}
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}
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}
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