EF - 添加到由 Id 设置的关联

发布于 2024-10-29 00:15:56 字数 520 浏览 1 评论 0原文

假设我有一个多对多的关系：

Song  *---*  Artist

我在我的代码中想要向歌曲添加艺术家。我知道艺术家的 ID，但没有 Artist 实体的实例。

目前我必须做类似的事情：

var artist = context.Artists.Single(a => a.Id == artistId);
song.Artists.Add(artist);

这涉及数据库查询。

多对多关系被建模为一个表：

SongId | ArtistId
-------+---------

出于性能原因，我想做的就是向该表添加一个条目，而不必转到数据库来加载我的一堆实体数据。不需要。

有没有办法用 EF 来做到这一点？例如，像这样的 API：

song.Artists.Add(artistId);

原文

Say I have a many to many relationship:

Song  *---*  Artist

I'm at a point in my code where I want to add an artist to the song. I know the artist's ID, but I don't have an instance of the Artist entity.

Currently I have to do something like:

var artist = context.Artists.Single(a => a.Id == artistId);
song.Artists.Add(artist);

This involves a DB query.

The many-to-many relationship is modelled as a table:

SongId | ArtistId
-------+---------

What I'd like to do, for performance reasons, is to just add an entry to this table without having to go to the DB to load a bunch of entity data that I don't need.

Is there a way to do this with EF? For example, an API like this:

song.Artists.Add(artistId);

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默嘫て 2024-11-05 00:15:56

您可以使用虚拟对象：

var song = context.Songs.Single(s => s.Id == songId);
var artist = new Artist { Id = artistId };
context.Artists.Attach(artist);
song.Artists.Add(artist);
context.SaveChanges();

You can use dummy object:

var song = context.Songs.Single(s => s.Id == songId);
var artist = new Artist { Id = artistId };
context.Artists.Attach(artist);
song.Artists.Add(artist);
context.SaveChanges();

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