ado.net实体数据模型父子关系

Scenario I am playing MVC NerdDinner project and using ado.net entity data model instead on 'dbml'

场景我正在玩MVC NerdDinner项目并使用ado.net实体数据模型代替'dbml'

I have 2 database tables Dinner & RSVP where RSVP contains DinnerID as foreign key from Dinner table.

我有2个数据库表Dinner和RSVP,其中RSVP包含DinnerID作为来自餐桌的外键。

Now when I am accessing a particular record from Dinner table, it returns a dinner object with RSVP property but there are no data with that property inspite of RSVP table having data with foreign key from Dinner table

现在,当我从Dinner表访问特定记录时,它返回一个具有RSVP属性的晚餐对象,但是尽管RSVP表具有来自Dinner表的外键数据,但没有该属性的数据

Data

DinnerTable

ID :1
Title : '.Net Architecture'

ID:1标题:'。Net Architecture'

RSVPTable

ID :1
Dinner ID: 1
AttendeeName : 'Miral'

ID:1晚餐ID:1 AttendeeName:'Miral'

ID :2
Dinner ID: 1
AttendeeName : 'Shivani'

ID:2晚餐ID:1 AttendeeName:'Shivani'

So when fetching Dinner data which should return its child RSVP data, I am getting RSVP property with 0 records.

因此,当获取应该返回其子RSVP数据的Dinner数据时,我获得了具有0条记录的RSVP属性。

2 个解决方案

#1

EF is a little different from LINQ. In your query, add something like

EF与LINQ略有不同。在您的查询中,添加类似的内容

var dinner = context.Dinners.First(d => d.DinnerID = id).Include("Attendees");

This will tell EF to attach the associated Attendees objects in a single fetch, doing all of the necessary joins for you.

这将告诉EF在一次获取中附加相关的Attendees对象,为您执行所有必要的连接。

#2

Correct syntax

Table : 'Dinner' & 'RSVP'

表:'晚餐'和'回复'

var dinner =_nerdDinnerEntities.Dinner.Include("RSVP").Where(dd => dd.ID == ID).FirstOrDefault();

var dinner = _nerdDinnerEntities.Dinner.Include(“RSVP”)。其中(dd => dd.ID == ID).FirstOrDefault();

Your require to write Include before FirstOrDefault.

您需要在FirstOrDefault之前写入Include。

'Include' is a method on Entity over here 'Dinner',and it includes table name containing the foreign key i.e. 'RSVP' and the property 'AttendeeName'.

'Include'是实体在这里'Dinner'的方法,它包括包含外键的表名,即'RSVP'和属性'AttendeeName'。

I tried passing one of the property 'AttendeeName' but it didnt worked.

我尝试传递其中一个属性'AttendeeName',但它没有用。

#1