protected override Expression VisitBinary(BinaryExpression node)
{
WhereExpression.Append("(");
Visit(node.Left);
CurrentOperator = WhereOperator.GetOperator(node.NodeType);
WhereExpression.AppendFormat(" {0} ", CurrentOperator);
Visit(node.Right);
WhereExpression.Append(")");
return(node);
}
protected override Expression VisitUnary(UnaryExpression node)
{
if (node.NodeType == ExpressionType.Not)
{
WhereExpression.Append(WhereOperator.GetOperator(node.NodeType));
Visit(node.Operand);
}
else
{
Visit(node.Operand);
}
return(node);
}
/// <summary>
/// 构建表达式
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="expressionList"></param>
/// <returns></returns>
public string Build <T>(ref DynamicParameters param, List <WhereExpression> expressionList)
{
ClassType = typeof(T);
Param = param;
foreach (var item in expressionList)
{
if ((!item.Equals(expressionList.FindAll(f => string.IsNullOrEmpty(f.StringWhere)).First())) && item.ExpressType != ExpressionType.Default)
{
WhereExpression.AppendFormat(" {0} ", WhereOperator.GetOperator(item.ExpressType ?? 0));
}
if (!string.IsNullOrEmpty(item.StringWhere))
{
WhereExpression.Append(item.StringWhere);
continue;
}
Visit(item.Expression);
}
return(WhereExpression.ToString());
}
protected override Expression VisitMethodCall(MethodCallExpression node)
{
if (node.Arguments.Count == 3 && WhereOperator.Methods.Contains(node.Method.Name) && node.Method.Name.Contains("Between"))
{
WhereExpression.Append("(");
CurrentOperator = WhereOperator.GetOperator(node.Method.Name);
Visit(node.Arguments[0]);
WhereExpression.AppendFormat(" {0} ", CurrentOperator);
Visit(node.Arguments[1]);
WhereExpression.AppendFormat(" AND ");
Visit(node.Arguments[2]);
WhereExpression.Append(")");
}
else if (node.Arguments.Count == 2 && WhereOperator.Methods.Contains(node.Method.Name))
{
WhereExpression.Append("(");
Visit(node.Arguments[0]);
CurrentOperator = WhereOperator.GetOperator(node.Method.Name);
WhereExpression.AppendFormat(" {0} ", CurrentOperator);
Visit(node.Arguments[1]);
WhereExpression.Append(")");
}
else if (node.Arguments.Count == 1 && WhereOperator.Methods.Contains(node.Method.Name))
{
WhereExpression.Append("(");
Visit(node.Arguments[0]);
CurrentOperator = WhereOperator.GetOperator(node.Method.Name);
WhereExpression.AppendFormat(" {0} ", CurrentOperator);
WhereExpression.Append(")");
}
else
{
var value = Expression.Lambda(node).Compile().DynamicInvoke();
SetValue(value);
}
return(node);
}
