public async Task GetImage(int id, Func <Stream, ImageInfo, Task> callback)
{
var imageInfo = await _connection.Images.SingleOrDefaultAsync(info => info.Id == id);
using (var trans = _connection.BeginTransaction())
{
using (var stream = await _largeObjectManager.OpenReadAsync(imageInfo.ImageId, CancellationToken.None))
{
await callback(stream, imageInfo);
}
}
}
public async Task <Stream> GetLOBBuffered(uint oid, DBTransaction transaction)
{
var outStream = new MemoryStream();
var manager = new NpgsqlLargeObjectManager((NpgsqlConnection)transaction.Connection);
var bufferSize = 81920;
var buffer = new byte[bufferSize];
using (var lobStream = await manager.OpenReadAsync(oid, CancellationToken.None))
{
int count;
while ((count = await lobStream.ReadAsync(buffer, 0, bufferSize)) != 0)
{
outStream.Write(buffer, 0, count);
}
}
outStream.Position = 0;
return(outStream);
}
public override async Task <Stream> GetLOB(uint oid, DBTransaction transaction, int bufferSize = 81920)
{
var manager = new NpgsqlLargeObjectManager((NpgsqlConnection)transaction.Connection);
return(await manager.OpenReadAsync(oid, CancellationToken.None));
}
public async Task <Result <FileResult, Unit> > Get(
string?userName,
DateTimeOffset?ifModifiedSince,
Guid id)
{
var contextData = await this.dbContext.Contexts
.Where(context =>
context.Project.PublicallyReadable ||
(context.Project.Owner.UserName == userName ||
context.Project.Contributors.Any(contributor => contributor.User.UserName == userName)))
.Select(context => new
{
Id = context.Id,
ContentObjectId = context.ContentObjectId,
MediaType = context.MediaType != null ? context.MediaType.MediaType : null,
Extension = context.MediaType != null ? context.MediaType.Extension : null,
LastModified = context.CreationTime
})
.FirstOrDefaultAsync(contextData => contextData.Id == id);
if (contextData == null)
{
return(Result <FileResult, Unit> .Failure(
HttpStatusCode.NotFound,
"context not found"));
}
if (contextData.ContentObjectId == null || contextData.MediaType == null)
{
return(Result <FileResult, Unit> .Failure(
HttpStatusCode.NotFound,
"context has no associated binary data"));
}
if (ifModifiedSince != null && contextData.LastModified < ifModifiedSince)
{
return(Result <FileResult, Unit> .Failure(
HttpStatusCode.NotModified,
"not modified"));
}
await this.dbContext.Database.OpenConnectionAsync();
var connection = (NpgsqlConnection)this.dbContext.Database.GetDbConnection();
// we have to begin a transaction, in order for LOB access to work
// (otherwise we get a "invalid large-object descriptor: 0" error)
// but we can't dispose it in this method, so we wrap the created stream
// in a wrapper that disposes another object after disposing the stream
var transaction = await this.dbContext.Database.BeginTransactionAsync();
var lobManager = new NpgsqlLargeObjectManager(connection);
return(Result <FileResult, Unit> .Ok(new FileResult()
{
Content = new DisposingStream(
await lobManager.OpenReadAsync(contextData.ContentObjectId.Value),
transaction),
FileName = $"{contextData.Id}.{contextData.Extension}",
MediaType = contextData.MediaType,
LastModified = contextData.LastModified
}));
}