/// <summary>
/// 根据结点数据计算最终条件表达式的值
/// </summary>
/// <param name="item">高级查询对象</param>
/// <returns>二元组</returns>
Tuple <string, object[]> CalcFinalExpr(AdvQueryItem item)
{
//检查查询项数据
if (item == null || item.Nodes == null)
{
return(null);
}
if (!item.Nodes.Exists(t => t.ParentId == 0))
{
return(null);
}
string whereExp = "";
IList <object> parameters = new List <object>();
//查询到根节点。
AdvQueryNode rootNode = item.Nodes.FirstOrDefault(t => t.ParentId == 0);
//生成ODT模型的对象
object odtObj = RefHelper.LoadClass(item.ModelName);
ProcessQueryNode(rootNode, item, odtObj, ref whereExp, ref parameters);
//是否有查询条件
if (parameters.Count == 0)
{
return(null);
}
Tuple <string, object[]> result = new Tuple <string, object[]>(whereExp, parameters.ToArray());
return(result);
}
/// <summary>
/// 处理一个查询定义节点。依次递归子节点循环。
/// </summary>
/// <param name="node">当前节点</param>
/// <param name="item">查询项集合</param>
/// <param name="odtObj"></param>
/// <param name="exp">查询表达式</param>
/// <param name="parameters">查询表达式参数</param>
private void ProcessQueryNode(AdvQueryNode node, AdvQueryItem item, object odtObj, ref string exp, ref IList <object> parameters)
{
if (node == null)
{
return;
}
//查询当前节点的子节点
List <AdvQueryNode> children = item.Nodes.Where(t => t.ParentId == node.Id).ToList();
if (children.Count == 0)
{
//没有子节点，这是一个表达式节点
if (node.Operator.IsEmpty())
{
return;
}
string p = "@" + parameters.Count;
if (node.Operator.Trim().ToUpper().Equals("LIKE"))
{
exp = exp + node.Expression.Trim() + ".Contains(" + p + ") ";
}
else if (node.Operator.Trim().ToUpper().Equals("NOT LIKE"))
{
exp = exp + " !" + node.Expression.Trim() + ".Contains(" + p + ") ";
}
else
{
exp = exp + " (" + node.Expression.Trim() + node.Operator + p + ") ";
}
RefHelper.SetValue(odtObj, node.Expression, node.Value);
parameters.Add(RefHelper.GetValue(odtObj, node.Expression));
return;
}
else
{
//有子节点，这是一个逻辑运算符节点
exp = exp + "(";
int i = 0;
foreach (AdvQueryNode child in children)
{
//子节点是逻辑运算符
if (child.Type.ToLower() == "operator")
{
if (!item.Nodes.Exists(t => t.ParentId == child.Id))
{
continue;
}
}
if (i > 0)
{
exp = exp + " " + node.Expression + " ";
}
//递归子节点循环。
ProcessQueryNode(child, item, odtObj, ref exp, ref parameters);
i++;
}
exp = exp + ")";
}
}
