实体框架 - 有条件地包括相关实体

Question

我维护一个API,它根据对人员列表的请求,根据请求返回不同的结果集.例如,某些API客户端希望获取人员列表和他们的交互列表,其他人希望获得人员和他们的元数据列表.所有这些都可以在请求返回人员的API方法时指定.

这似乎不起作用:

using (var dbcontext = new ExampleEntities())
{
    var query = dbcontext.People.AsQueryable();
    //determined in earlier application logic based on request
    if(includeMetadata)
    {
        query = query.Include("metadata");
    }
    //determined in earlier application logic based on request
    if(includeInteractions) 
    {
        query = query.Include("interactions");
    }
    /* ...SNIP... */
}

我不想做的是:

var query = dbcontext.People.Include("Metadata").Include("interactions");

即使请求的API客户端不需要它们,这意味着每个获取一个人的请求都将包括所有相关实体.

我也不想编写每种可能的逻辑组合:

if(includeMetadata && includeInteractions)
{
    var query = dbcontext.People.Include("Metadata").Include("interactions");

}
else if(includeMetadata)
{
    var query = dbcontext.People.Include("Metadata");
}
else if(includeInteractions)
{
    var query = dbcontext.People.Include("Interactions");
}
else
{
    var query = dbcontext.People;
}

这将导致难以维护的代码,但是,我意识到如果需要我可以生成代码.

Answer 1

你可以链接IQueryable

using (var dbcontext = new ExampleEntities())
{
    var query = dbcontext.People.AsQueryable();
    if(includeMetadata)
    {
        query = query.Include("metadata");
    }
    if(includeInteractions) 
    {
        query = query.Include("interactions");
    }    
}