从不在MyList中的实体中选择 <T> （字段）使用实体框架

Question

I have some code to check if my version field in DB is contained in any of item in MyList<EntityPoco> .

I want to know if there is a better way or simpler method to do this than what I already have:

List<Model.Job> jobs = mapperJobs.Map(dt).ToList();

bool itemExists = false;

foreach (Model.Job job in jobs)
{
    var result = db.Jobs.Where(a => (a.Version == job.Version));

    // If the item exists move on.
    if (result.Any())
    {
        itemExists = true;
        break;
    }

    // Else we need to insert a new record in the db 
    if (!itemExists)
    {
        db.Jobs.Add(job);
    }
} // ... db save changes after adding everything we want

Answer 1

You can't do a join in EF to an in-memory collection, bout you can extract a list of values and use Contains :

var jobVersions = jobs.Select(job => job.Version).ToArray();
var result = db.Jobs.Where(a => jobVersions.Contains(a.Version));