Develop Reference

How to set ContentMD5 in DataLakeFileClient?

When uploading to an Azure Data Lake using the Microsoft Azure Storage Explorer the file automatically generates and stores a value for the ContentMD5 property. It also automatically does it in a function app that uses a Blob binding.
However, this does not automatically generate when uploading from a C# DLL.
I want to use this value to compare files in the future.
My code for the upload is very simple.
DataLakeFileClient fileClient = await directoryClient.CreateFileAsync("testfile.txt");
await fileClient.UploadAsync(fileStream);
I also know I can generate an MD5 using the below code, but I'm not certain if this is the same way that Azure Storage Explorer does it.
using (var md5gen = MD5.Create())
{
md5hash = md5gen.ComputeHash(fileStream);
}
but I have no idea how to set this value to the ContentMD5 property of the file.

I have found the solution.
The UploadAsync method has an overload that accepts a parameter of type DataLakeFileUploadOptions. This class contains a HttpHeaders object which in turn has a ContentHash property which stores it as a property of the document.
var uploadOptions = new DataLakeFileUploadOptions();
uploadOptions.HttpHeaders = new PathHttpHeaders();
uploadOptions.HttpHeaders.ContentHash = md5hash;
await fileClient.UploadAsync(fileStream, uploadOptions);

Convert HttpUploadedFileWrapper to something not in System.Web

I've implemented a file upload in ASP.Net MVC. I've created a view model that received the uploaded file as an HttpPostedFileWrapper and within the controller action I can save the file to disk.
However, I want to perform the actual save in service method which is in a class library that doesn't implement System.Web. I can't therefore pass the HttpPostedFileWrapper object to the service method.
Does anyone know how to achieve this, either by receiving the file as a different object or converting it to something else prior to passing it. The only way I can think of is to read the content of the file into a MemoryStream, and pass this along with the other parameters such as filename individually, but just wondered if there was a better way?
Thanks

The best approach would probably be retrieving the image data (as a byte[]) and the name of the image (as a string) and passing those along to your service, similar to the approach you mentioned :
public void UploadFile(HttpPostedFileWrapper file)
{
// Ensure a file is present
if(file != null)
{
// Store the file data
byte[] data = null;
// Read the file data into an array
using (var reader = new BinaryReader(file.InputStream))
{
data = reader.ReadBytes(file.ContentLength);
}
// Call your service here, passing along the data and file name
UploadFileViaService(file.FileName, data);
}
}
Since a byte[] and a string are very basic primatives, you should have no problem passing them to another service. A Stream is likely to work as well, but they can be prone to issues like being closed, whereas a byte[] will already have all of your content.

Saving, loading and manipulating (listview) data C#

I'm working on an UWP application where a user can input data which is placed in a listview. All fine and dandy, but how can I save the user data to a separate file and load it the next time a user boots up the app?
I've tried to find a solution, but I had great difficulty to understand these code snippets and on how to apply these (since I'm fairly new to C# and App development). Would somebody like to explain how I can achieve the saving/loading of the data and explain what the code does?
Thanks in advance! :)

You can create a file like this:
StorageFile ageFile = await local.CreateFileAsync("Age.txt", CreationCollisionOption.FailIfExists);
I can read and write to a file like this:
StorageFolder local = Windows.Storage.ApplicationData.Current.LocalFolder;
var ageFile = await local.OpenStreamForReadAsync(#"Age.txt");
// Read the data.
using (StreamReader streamReader = new StreamReader(ageFile))
{
//Use like a normal streamReader
}
if you are trying to write, use OpenStreamForWriteAsync;

If I understood well, you have some kind of object structure that serves as a model for your ListView. When the application is started, you want to read a file where the data is present. When closing the application (or some other event) write the file with the changes done. Right?
1) When your application is loaded / closed (or upon modifications or some event of your choice), use the Windows.Storage API to read / write the text into the file.
2) If the data you want to write is just a liste of strings, you can save this as is in the file. If it is more complicated, I would recommend serializing it in JSON format. Use JSON.NET to serialize (object -> string) and deserialize (object <- string) the content of your file and object structure.
Product product = new Product();
product.Name = "Apple";
...
string json = JsonConvert.SerializeObject(product);

Sitecore media library paths

Using Sitecore 6.5, when images are rendered on a web page, a URL such as the one below is used
~/media/OSS/Images/MyImage
But if you add an image from the library in a content editor a path such as below is used
~/media/1CFDDC34C94E460FAA2B1518DCA22360.PNG
This makes sense as it's trying to use a meaningful path when rendered for the web.
We would like to use the first media image path to add images in the content editor in HTML view rather than the default second method. This is because we are actually taking some html files and automatically adding them in to Sitecore via a script and we can change the image paths to a location in the media library if the first image format is used by using a convention so the images should appear in the newly created items. We have now idea about a media library image ID.
The first format does appear to work as images are rendered in the content editor design editor and when the page is rendered but Sitecore marks these as broken links in the Content Editor. Are any ideas on whether we are safe to use this format?

You may want to avoid hard coding paths to media in the rich text field. The second "dynamic link" is an important feature of Sitecore in that it keeps a connection between the media and item in the Links database. This safeguards you if you ever delete or move the media.
Since it sounds like you are importing content from an external source and you already have a means of detecting the image paths, I would recommend (if possible) that you upload the images programmatically and insert the dynamic links.
Below is a function that you can call for uploading to the Media Library and getting back the media item:
Example usage:
var file = AddFile("/assets/images/my-image.jpg", "/sitecore/media library/images/example", "my-image");
The code:
private MediaItem AddFile(string relativeUrl, string sitecorePath, string mediaItemName)
{
var extension = Path.GetExtension(relativeUrl);
var localFilename = #"c:\temp\" + mediaItemName + extension;
using (var client = new WebClient())
{
client.DownloadFile("http://yourdomain.com" + relativeUrl, localFilename);
}
// Create the options
var options = new MediaCreatorOptions
{
FileBased = false,
IncludeExtensionInItemName = false,
KeepExisting = false,
Versioned = false,
Destination = sitecorePath + "/" + mediaItemName,
Database = Factory.GetDatabase("master")
};
// Now create the file
var creator = new MediaCreator();
var mediaItem = creator.CreateFromFile(localFilename, options);
return mediaItem;
}
As for generating the dynamic link to the media, I actually haven't found a Sitecore method to do this, so I resorted to the following code:
var extension = !String.IsNullOrEmpty(Settings.Media.RequestExtension)
? Settings.Media.RequestExtension
: ((MediaItem)item).Extension;
var dynamicMediaUrl = String.Format(
"{0}{1}.{2}",
MediaManager.MediaLinkPrefix,
item.ID.ToShortID(),
extension);

No it will not cause any rendering issue apart from the broken links notification as you noted. Also when you select an image in the editor and select to edit the media folder will be at the root rather than at the image itself. But as Derek has noted, the use of dynamic links is an important feature to make sure your links do not break if something is moved or deleted.
I would add to his answer that since you are adding the text via a script you can detect images in the text using HtmlAgilityPack (already used in Sitecore) or FizzlerEx (more similar to jQuery syntax), use the code he provided to upload the images to the media library, grab the GUID and replace the src. Something along the lines of:
string content = "<whatever your html to go in the rich text field>";
HtmlDocument doc = new HtmlDocument();
doc.Load(content);
foreach(HtmlNode img in doc.DocumentElement.SelectNodes("//img[starts-with(#src, '/media/')]")
{
HtmlAttribute attr = img["src"];
Item scMediaItem = UploadLocalMedia(attr.Value);
attr.Value = GetDynamicMediaUrl(scMediaItem);
}

Silverlight Loading Reference Data On Demand from a 'dumb' server

I have a text file with a list of 300,000 words and the frequency with wich they occur. Each line is in the format Word:FequencyOfOccurence.
I want this information to be accessible from within the C# code. I can't hard code the list since it is too long, and I'm not sure how to go about accessing it from a file on the server. Ideally I'd ideally like the information to be downloaded only if it's used (To save on bandwidth) but this is not a high priority as the file is not too big and internet speeds are always increasing.
It doesn't need to be useable for binding.
The information does not need to be editable once the project has been built.

Here is another alternative. Zip the file up and stick it in the clientBin folder next to the apllication XAP. Then at the point in the app where the content is needed do something like this:-
public void GetWordFrequencyResource(Action<string> callback)
{
WebClient client = new WebClient();
client.OpenReadAsync += (s, args) =>
{
try
{
var zipRes = new StreamResourceInfo(args.Result, null)
var txtRes = Application.GetResourceStream(zipRes, new Uri("WordFrequency.txt", UriKind.Relative));
string result = new StreamReader(txtRes.Stream).ReadToEnd();
callback(result);
}
catch
{
callback(null); //Fetch failed.
}
}
client.OpenReadAsync(new Uri("WordFrequency.zip", UriKind.Relative"));
}
Usage:-
var wordFrequency = new Dictionary<string, int>();
GetWordFrequencyResource(s =>
{
// Code here to burst string into dictionary.
});
// Note code here is asynchronous with the building of the dictionary don't attempt to
// use the dictionary here.
The above code allows you to store the file in an efficient zip format but not in the XAP itself. Hence you can download it on demand. It makes use of the fact that a XAP is a zip file so Application.GetResourceStream which is designed to pull resources from XAP files can be used on a zip file.
BTW, I'm not actually suggesting you use a dictionary, I'm just using a dictionary as simple example. In reality I would imagine the file is in sorted order. If that is the case you could use a KeyValuePair<string, int> for each entry but create a custom collection type that holds them in an array or List and then use some Binary search methods to index into it.

Based on your comments, you could download the word list file if you are required to have a very thin server layer. The XAP file containing your Silverlight application is nothing more than a ZIP file with all the referenced files for your Silverlight client layer. Try adding the word list as content that gets compiled into the XAP and see how big the file gets. Text usually compresses really well. In general, though, you'll want to be friendly with your users in how much memory your application consumes. Loading a huge text file into memory, in addition to everything else you need in your app, may untimately make your app a resource hog.
A better practice, in general, would be to call a web service. The service could would perform whatever look up logic you need. Here's a blog post from a quick search that should get you started: (This was written for SL2, but should apply the same for SL3.)
Calling web services with Silverlight 2
Even better would be to store your list in a SQL Server. It will be much easier and quicker to query.

You could create a WCF service on the server side that will send the data to the Silverlight application. Once you retrieve the information you could cache it in-memory inside the client. Here's an example of calling a WCF service method from Silverlight.
Another possibility is to embed the text file into the Silverlight assembly that is deployed to the client:
using (var stream = Assembly.GetExecutingAssembly()
.GetManifestResourceStream("namespace.data.txt"))
using (var reader = new StreamReader(stream))
{
string data = reader.ReadToEnd();
// Do something with the data
}