LINQ 到实体：如何通过谓词获取所有值

Question

I'm trying to get all values that has the same predicate. For example: i have many Packages records that consist of it's own Id, Data and DeviceId which indicates from which device the package has arrived.

Here's the function that I have created which only returns the first package

 public Package GetPackageByDeviceId(int id)
    {
        return avldbContext.Packages.Where(p => p.DeviceId == id).FirstOrDefault();
    }

Any advices on how to get all packages?

Answer 1

public IEnumerable<Package> GetPackagesByDeviceId(int id)
{
    return avldbContext.Packages.Where(p => p.DeviceId == id);
}

Answer 2

public List<Package> PackagesByDeviceId(int id)
{
    return avldbContext.Packages.Where(p => p.DeviceId == id).ToList();
}

First, you need to specify "s" char end of your method. Because the method returns multiple rows. Than without FirstOrDefault(). You need to put a ToList() extension method to pull all records. Good luck.

edit: By the way, your code looks like still looking for primary key. You need to scale your prediction.

Answer 3

If you want to get IEnumerable result

public IEnumerable<Package> GetPackagesByDeviceId(int id)
{
    return avldbContext.Packages.Where(p => p.DeviceId == id);
}

Or if you want to get List

public List<Package> GetPackagesByDeviceId(int id)
{
    return avldbContext.Packages.Where(p => p.DeviceId == id).ToList();
}