// Open a readable stream for the current input file.
// This is called only when necessary, i.e first time the document is loaded. For consecutive views
// as long as cached files are valid, it will not be called. This can be also called when "Download"
// button is clicked to download the original document.
//
// inputFile parameter will be the value that was set in DocumentViewer.Document property, i.e.
// the input file that was requested to be loaded in DocumentViewer
//
// inputOptions parameter will be determined according to the input document format
// Usually you will not need to check this parameter as inputFile parameter should be sufficient
// for you to locate and open a corresponding stream.
//
// Return a StreamResult instance initialized with a readable System.IO.Stream object.
public StreamResult OpenRead(string inputFile, InputOptions inputOptions, DocumentHandlerParameters handlerParameters)
{
var fileId = inputFile;
byte[] fileBytes;
// Get your parameters that were set in documentViewer.DocumentHandlerParameters property
// The type for the generic Get<T> method should be the same as the set value's type.
var connectionString = handlerParameters.Get <string>("connectionString");
using (var connection = new SqlConnection(connectionString))
{
connection.Open();
var sql = "SELECT FileBytes FROM FileTable WHERE FileId=" + fileId;
using (var command = new SqlCommand(sql))
using (var reader = command.ExecuteReader())
{
if (!reader.Read())
{
throw new Exception("File not found");
}
// read the file data from the selected row (first column in above query)
fileBytes = (byte[])reader.GetValue(0);
}
}
// We need to return a stream that has the file contents here.
// As we don't have a stream but a byte array, we can wrap it with a MemoryStream.
var stream = new MemoryStream(fileBytes);
return(new StreamResult(stream));
}
// Get the document information required for the current input file.
// This is called for determining the cache key and document format whenever
// DocumentViewer requests a document.
//
// inputFile parameter will be the value that was set in DocumentViewer.Document property, i.e.
// the input file that was requested to be loaded in DocumentViewer
//
// Return a DocumentInfo instance initialized with required information from this method.
public DocumentInfo GetInfo(string inputFile, DocumentHandlerParameters handlerParameters)
{
var fileId = inputFile;
string fileName;
// Get your parameters that were set in documentViewer.DocumentHandlerParameters property
// The type for the generic Get<T> method should be the same as the set value's type.
var connectionString = handlerParameters.Get <string>("connectionString");
using (var connection = new SqlConnection(connectionString))
{
connection.Open();
var sql = "SELECT FileName FROM FileTable WHERE FileId=" + fileId;
using (var command = new SqlCommand(sql, connection))
using (var reader = command.ExecuteReader())
{
if (!reader.Read())
{
throw new Exception("File not found");
}
// read the file name from the selected row (first column in above query)
fileName = reader.GetString(0);
}
}
return(new DocumentInfo(
// uniqueId parameter (required):
// The unique identifier that will be used for generating the cache key for this document.
// For instance, it can be an ID from your database table or a simple file name;
// you just need to make sure this ID varies for each different document so that they are cached correctly.
// For example for files on disk,
// we internally use a string combination of file extension, file size and file date for uniquely
// identifying them, this way cache collisions do not occur and we can resuse the cached file
// even if the file name before extension is changed (because it's still the same document).
fileId,
// fileName parameter (optional but recommended):
// The file name which will be used for display purposes such as when downloading the document
// within DocumentViewer> or for the subfolder name prefix in cache folder.
// It will also be used to determine the document format from extension if format
// parameter is not specified. If not specified or empty, uniqueId will be used
// as the file name.
fileName
));
}