1

DB MetersTree 表

id       text   parentId    state

 0       root          0     open
 1    level 1          1     open
 2    level 1          1     open
 ...

控制器

public ActionResult GetDemoTree()
{
    OsosPlus2DbEntities entity = new OsosPlus2DbEntities();
    MetersTree meterTree = entity.MetersTree.FirstOrDefault();

    return Json(meterTree, JsonRequestBehavior.AllowGet);
}

应该是（例如）的数据格式

[{  
    "id": 1,  
    "text": "Node 1",  
    "state": "closed",  
    "children": [{  
        "id": 11,  
        "text": "Node 11"  
    },{  
        "id": 12,  
        "text": "Node 12"  
    }]  
},{  
    "id": 2,  
    "text": "Node 2",  
    "state": "closed"  
}]

如何创建树 Json 数据？如果我用它的关系编写 MetersTree，我会得到标题中定义的错误。

4

2 回答 2

3

您需要打破由于 EF 类中的导航属性而被拾取的循环引用。

您可以将结果映射到这样的匿名类型，尽管这是未经测试的： 

public ActionResult GetDemoTree()
{
    OsosPlus2DbEntities entity = new OsosPlus2DbEntities();
    MetersTree meterTree = entity.MetersTree.FirstOrDefault();

    var result = from x in meterTree
           select new 
            {
            x.id,
            x.text,
            x.state,
            children = x.children.Select({
                c => new {
                    c.id,
                    c.text
                })
         };

    return Json(result, JsonRequestBehavior.AllowGet);
}
于 2012-12-13T16:13:34.133 回答
1

我是这样解决的：

查看模型

public class MetersTreeViewModel
{
    public int id { get; set; }
    public string text { get; set; }
    public string state { get; set; }
    public bool @checked { get; set; }
    public string attributes { get; set; }
    public List<MetersTreeViewModel> children { get; set; }
}

控制器

public ActionResult GetMetersTree()
{
    MetersTree meterTreeFromDb = entity.MetersTree.SingleOrDefault(x => x.sno == 5); //in my db this is the root.
    List<MetersTreeViewModel> metersTreeToView = buildTree(meterTreeFromDb.Children).ToList();

    return Json(metersTreeToView, JsonRequestBehavior.AllowGet);
}

构建树方法

private List<MetersTreeViewModel> BuildTree(IEnumerable<MetersTree> treeFromDb)
{
    List<MetersTreeViewModel> metersTreeNodes = new List<MetersTreeViewModel>();
    foreach (var node in treeFromDb)
    {
        if (node.Children.Any())
        {
            metersTreeNodes.Add(new MetersTreeViewModel
            {
                id = node.sno,
                text = node.Text,
                state = node.Text,
                children = BuildTree(node.Children)
            });
        }
        else {
            metersTreeNodes.Add(new MetersTreeViewModel
            {
                id = node.sno,
                text = node.Text,
                state = node.Text
            });
        }
    }

    return metersTreeNodes;
}

感谢所有对...感兴趣的人

于 2012-12-14T12:46:12.240 回答