我们正在为我们的 C#.NET 项目在 Mongo DB 上做一个小峰值,看看它是否适合我们,我在 samus 的 mongodb-csharp 驱动程序上遇到了一个小问题,我不确定如何实现。
给定以下简化模型:
public class Campaign
{
public string Name { get; set; }
public IEnumerable<Placement> Placements { get; set; }
}
public class Placement
{
public string Name { get; set; }
//this should be a reference rather than included in the collection
public Site Site { get; set; }
}
//this should be its own collection, and not embedded anywhere
public class Site
{
public string Name { get; set; }
}
正如上面的评论所暗示的,我们正试图弄清楚如何将站点保存为引用类型,而不是嵌入到展示位置中。网站是它自己的顶级集合,独立于每个广告系列而变化。
理想情况下,我想使用 MongoConfigurationBuilder 来执行此操作,而不必修改我的 POCO。我似乎找不到任何有关如何完成此操作的文档。
我希望它会像这样简单:
var config = new MongoConfigurationBuilder();
config.Mapping(mapping =>
{
//maybe some more configuration here?
mapping.Map<Site>();
mapping.Map<Campaign>();
});
但是当我使用以下代码时,它仍然是嵌入站点:
var db = mongo.GetDatabase("foo");
var campaignCollection = db.GetCollection<Campaign>();
var siteCollection = db.GetCollection<Site>();
var firstSite = new Site{Name = "first site"};
var secondSite = new Site{Name = "second site"};
var firstCampaign = new Campaign
{
Name = "first campaign",
Placements = new List<Placement>
{
new Placement{Name = "first placement", Site = firstSite},
new Placement{Name = "second placement", Site = secondSite}
}
};
siteCollection.Save(firstSite);
siteCollection.Save(secondSite);
campaignCollection.Save(firstCampaign);
这是给我们的:
{ "_id" : ObjectId("4ca9f1db54730000000010cb"),
"Name" : "first campaign",
"Placements" : [
{
"Name" : "first placement",
"Site" : { "Name" : "first site" }
},
{
"Name" : "second placement",
"Site" : { "Name" : "second site" }
}
]}
{ "_id" : ObjectId("4ca9f1db54730000000010c9"), "Name" : "first site" }
{ "_id" : ObjectId("4ca9f1db54730000000010ca"), "Name" : "second site" }
而我们想要的更像是:
{ "_id" : ObjectId("4ca9f1db54730000000010cb"),
"Name" : "first campaign",
"Placements" : [
{
"Name" : "first placement",
"Site" : ObjectId("4ca9f1db54730000000010c9")
},
{
"Name" : "second placement",
"Site" : ObjectId("4ca9f1db54730000000010ca")
}
]}
{ "_id" : ObjectId("4ca9f1db54730000000010c9"), "Name" : "first site" }
{ "_id" : ObjectId("4ca9f1db54730000000010ca"), "Name" : "second site" }
我不确定这是否是我们最终得到的确切文件,但你明白了。
我觉得好像我遗漏了一些明显的东西,但是如果没有更好的关于驱动程序这方面的文档,我有点在黑暗中拍摄。我什至查看了源代码中的测试,但无法弄清楚。
有人知道怎么做吗?有可能吗?
最佳答案
为此,您必须使用 DBRef .
要在 c# 中执行此操作,您必须像这样更改广告系列类
public class Campaign
{
public string Name { get; set; }
public List<DBRef> Placements { get; set; }
}
并像这样插入引用文档
List<DBRef> refList = new List<DBRef>() {firstSite,secondSite };
var firstCampaign = new Campaign
{
Name = "first campaign",
Placements = refList
};
campaignCollection.Save(firstCampaign);
我还没有测试过代码,但这给出了如何完成的提示。
关于mongodb-csharp 驱动程序 - 如何将属性保存为引用而不是嵌入?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3857214/