Question

Database Diagram

我有这样的数据库结构。每个员工都属于一个部门，每个部门都属于一个部门，每个部门都有一个员工清单和与之相关的股票清单。我使用以下代码初始化数据库：

$data.define("Org.Department",{
  ID: {key: true, type: "integer", computed: true},
  DepartmentID: {type: "integer", required: true},
  DepartmentName: {type: "string", required: true},
  Employee:{type: Array, elementType: "Org.Employee", navigationProperty:"Department"},
  Stock:{type: Array, elementType: "Org.Stock", navigationProperty:"Department"}
});

$data.define("Org.Employee",{
  ID: {key: true, type: "integer", computed: true},
  Name: {type: "string", required: true},
  DepartmentID: {type: "integer", required: true},
  Department: {type: "Org.Department", inverseProperty: "Employee"}
});

$data.define("Org.Stock",{
  ID: {key: true, type: "integer", computed: true},
  DepartmentID: {type: "integer", required: true},
  Description: {type: "string"},
  NumItems: {type: "integer", required: true},
  Department: {type: "Org.Department", inverseProperty: "Stock"}
});

$data.EntityContext.extend("Company",{
  Employees: {type: $data.EntitySet, elementType: Org.Employee},
  Departments: {type: $data.EntitySet, elementType: Org.Department},
  Stocks: {type: $data.EntitySet, elementType: Org.Stock}
});

var x= new Company({
  provider: "webSql",
  databaseName: "DB",
  version: 1,
  dbCreation: $data.storageProviders.DbCreationType.DropAllExistingTables
});

我想要做的是向该数据库添加元素，但我必须建立正确的连接。我的意思是正确的连接，我想查询所有员工的姓名，这些员工要求我查找部门名称并从中获取员工列表，然后列出他们的名字。我尝试过很多东西，但它彻底失败了。例如：

x.onReady(function(){
  var dep;
  x.Departments.filter(function(res){
    return res.DepartmentID==4;
  }).forEach(function(it){
    dep=it;
  });
  console.log(dep);
    var emp=new Org.Employee({
    Name: 'Employee1',
    DepartmentID: 4,
    Department:dep
  });
  x.Employees.add(emp);
  x.Employees.saveChanges();
});

未能在员工中插入正确的部门信息。当我查询Employee1的Department字段时，我得到了未定义。

这也失败了：

x.Employees.add({Name:"Employee1",DepartmentID:4});

所有查询都成功地将一些数据插入数据库，但是他们的Department字段为空，这违背了拥有关系数据库的全部目的。

Answer 1

我在代码中修复了两个重要的事情，现在它正在运行：

navigationProperty应为inverseProperty。你总是要用inverseProperty定义关系的另一面 - 请分享你找到这个navigationProperty的URL，我检查一下我是否可以修复它
如果您从数据库中读取项目并将其设置为关系，则必须将该项目附加到上下文

$ data.define（ “Org.Department”，{ ID：{key：true，type：“int”，computed：true}， DepartmentID：{type：“int”，required：true}， DepartmentName：{type：“string”，required：true}，员工：{type：Array，elementType：“Org.Employee”，inverseProperty：“Department”}，库存：{type：Array，elementType：“Org.Stock”，inverseProperty：“Department”} }）;

固定代码：

$data.define("Org.Employee",{
  ID: {key: true, type: "int", computed: true},
  Name: {type: "string", required: true},
  DepartmentID: {type: "int", required: true},
  Department: {type: "Org.Department", inverseProperty: "Employee"}
});

$data.define("Org.Stock",{
  ID: {key: true, type: "int", computed: true},
  DepartmentID: {type: "int", required: true},
  Description: {type: "string"},
  NumItems: {type: "int", required: true},
  Department: {type: "Org.Department", inverseProperty: "Stock"}
});

$data.EntityContext.extend("Company",{
  Employees: {type: $data.EntitySet, elementType: Org.Employee},
  Departments: {type: $data.EntitySet, elementType: Org.Department},
  Stocks: {type: $data.EntitySet, elementType: Org.Stock}
});

var x= new Company({
  provider: "webSql",
  databaseName: "DB",
  version: 1
});

x.onReady(function(){
    var newDep = new x.Departments.elementType({DepartmentName: 'dep1', DepartmentID: 7});
    x.Departments.add(newDep);
    x.saveChanges(function() {
        x.Departments.first("it.DepartmentName == 'dep1'", {}, function(dep){
              console.log(dep);
              x.Departments.attach(dep);
              var emp = new Org.Employee({
                Name: 'Employee1',
                DepartmentID: dep.DepartmentID,
                Department:dep
              });
              console.log(emp);
              x.Employees.add(emp);
              x.Employees.saveChanges();
        });
    })
});

您可以在jsfiddle

Jaydata中的复场操纵

1 个答案: