Extjs 为什么树存储上的同步不是嵌套节点

我使用的是一个带有treestore的treepanel和带有3层节点的treemodel。我想向存储添加节点，然后通过服务器api同步存储。对于嵌套存储的读取来说，一切都很好。下面是我向服务器api发送get时的数据示例：

{
"children" : [{
        "region" : 1,
        "label" : "Paris",
        "children" : [{
                "schoolId" : 1,
                "type" : "elementry"
                "address" : "1 rue generale",
                "children" : [{
                        "classId" : 1,
                        "teacher" : "Smith",
                        "year" : 1,
                        "leaf" : true
                    }, {
                        "classId" : 2,
                        "teacher" : "Alan",
                        "year" : 1,
                        "leaf" : true
                    }, {
                        "classId" : 3,
                        "teacher" : "Larkin",
                        "year" : 2,
                        "leaf" : true
                    }, {
                        "classId" : 4,
                        "teacher" : "Sharp",
                        "year" : 2,
                        "leaf" : true
                    }
                ]
            }, {
                "schoolId" : 2,
                "type" : "elementry"
                "address" : "1 rue de gaulle",
                "children" : [{
                        "classId" : 5,
                        "teacher" : "Mathew",
                        "year" : 1,
                        "leaf" : true
                    }, {
                        "classId" : 6,
                        "teacher" : "Mark",
                        "year" : 1,
                        "leaf" : true
                    }, {
                        "classId" : 7,
                        "teacher" : "Luke",
                        "year" : 2,
                        "leaf" : true
                    }, {
                        "classId" : 8,
                        "teacher" : "John",
                        "year" : 2,
                        "leaf" : true
                    }
                ]
            }, {
                "schoolId" : 3,
                "type" : "middle"
                "address" : "99 avenue de larre",
                "children" : [{
                        "classId" : 7,
                        "teacher" : "Lisa",
                        "year" : 5,
                        "leaf" : true
                    }, {
                        "classId" : 8,
                        "teacher" : "Bart",
                        "year" : 6,
                        "leaf" : true
                    }]
            }]
    }]
}

但是，当我添加子节点并发送sync命令时，生成的post请求不是嵌套的。附加子节点的代码：

var store = me.getViewModel().getStore('schoolStore');
var region = new WEBI.model.Region({
                    "label" :"Bordeaux"                                 
                });
var school = new WEBI.model.School({
                    "type" : "elementry",                   
                    "address" : "10 rue Bidart"     
                });
region.appendChild(school);
store.root.appendChild(region);
store.sync();

post请求中的数据采用以下格式：

[{
    "label" : "Bordeaux"
    "region" : "Region-1",
    "parentId" : "root",
    "leaf" : false
}, {
    "type" : "elementry",
    "address" : "10 rue Bidart"
    "idtsl2" : "School-1",
    "parentId" : "Region-1",
    "leaf" : false
}]

我期待/希望post请求将嵌套ITME（具有以下格式）

[{
    "label" : "Bordeaux"
    "region" : "Region-1",
    "parentId" : "root",
    "leaf" : false,
    "children" : [{
            "type" : "elementry",
            "address" : "10 rue Bidart"
            "idtsl2" : "School-1",
            "parentId" : "Region-1",
            "leaf" : false
        }
    ]
}]

还有其他人看到过同样的问题吗。这是一个必须处理此格式的post请求的问题，还是有某种方法可以配置我的代理/模型以嵌套格式发送post