EntityFramework Core 2.0 skip loading column

问题

I'm having some files saved into a MSSQL database using EF core with a structure like

public class UploadedFile
{
    public int Id { get; set; }
    public string Source { get; set; }
    public byte[] Content { get; set; }

I want to be able to load the list of "UploadedFiles" from database without actually reading the Content column from the database. So I can't really use

await _context.UploadedFiles.ToListAsync();

I believe I can use something like bellow with a stored procedure.

_context.Set<UploadedFiles>().FromSql("dbo.spGetUploadedFiles")

But, is there any other way that would not involve using a stored procedure? I can't un-map the column in the model as I need it for insert/read individual items. Thank you.

回答1:

Use a projection:

var results = _context.UploadedFiles.Select(uf => new { uf.Id, uf.Source });

回答2:

You can basically use .Select({..) to specify which columns you want to return:

public class MyItem
{
    public int Id { get; set; }
    public string Source { get; set; }
}

var data = _context.UploadedFiles
    .Select(p => new MyItem
    {
        Id = p.Id,
        Source = p.Source
    })
    .ToListAsync();

This way you tell EF to generate the select only for those columns and nothing more. You can also select an anonymous object like .Select(p => new { ... }) if you feel like so.

I strongly recommend using strong types.

来源：https://stackoverflow.com/questions/46122299/entityframework-core-2-0-skip-loading-column