Is there a implementation of GridFS in Morphia? How is this?
I am using a webservice and receive base64 input, which is transform in a bit array, such like this:
private bit [] image;
I created my model class to communicate with morphia, however, each document of that collection will have a lot of images, is something like an event has a lot of editions and an edition has its images.
How can I mapped that attribute in morphia?
GridFS is not yet supported by Morphia, if you want to store information into GridFS from your application you need to use the native Java GridFS API ( see https://github.com/mongodb/mongo-java-driver/blob/master/src/test/com/mongodb/gridfs/GridFSTest.java )
To answer your question
How can I mapped that attribute in morphia?
The code you have written will work, and your images will be saved as bytes into the document, in the attribute "image" like any other attribute. As you probably know MongoDB & Morphia are using BSON in memor, on the network and in the database, this means it will save the bytes as they are sent.
So of you still want to store the image in the document, not an issue at all if they are small, you just have to be careful about the overall size of the document. As you probably know a document cannot exceed 16Mb.
Related
My Mysql database stores images (in PNG, JPG)of our personnel and it's field type is set to longblob.
Is there any possibility to load blob data type using HttpService and render it in Image component in Flex .??? ^..^
I'm eager to know about as it comes in handy in the nearest future!!!
You can, but I don't see the point of storing your images in a DB.
Simplest way to get it into an Image is to load the blob, convert to a ByteArray which you can set as the source of of said Image.
If you override HttpService you can use it to receive binary data. If you don't want to override HttpService you have the option of encoding you binary data in base64 before sending it.
But if have the option to store the images in a directory on the server and just send links to the client - that would be a better solution.
I am using file upload mechanism to upload file for an employee and converting it into byte[] and passing it to varBinary(Max) to store into database.
Now I what I have to do is, if any file is already uploaded for employee, simply read it from table and show file name. I have only one column to store a file and which is of type VarBinary.
Is it possible to get all file information from VarBinary field?
Any other way around, please let me know.
If you're not storing the filename, you can't retrieve it.
(Unless the file itself contains its filename in which case you'd need to parse the blob's contents.)
If the name of the file (and any other data about the file that's not part of the file's byte data) needs to be used later, then you need to save that data as well. I'd recommend adding a column for the file name, perhaps one for its type (mime type or something like that for properly sending it back to the client's browser, etc.) and maybe even one for size so you don't have to calculate that on the fly for each file (useful when displaying a grid of files and not wanting to touch the large blob field in the query that populates the grid).
Try to stay away from using the file name for system-internal identity purposes. It's fine for allowing the users to search for a file by name, select it, etc. But when actually making the request to the server to display the file it's better to use a simple integer primary key from the table to actually identify it. (On a side note, it's probably a good idea to put a unique constraint on the file name column.)
If you also need help displaying the file to the user, you'll probably want to take the approach that's tried and true for displaying images from a database. Basically it involves having a resource (generally an .aspx page, but could just as well be an HttpHandler instead) which accepts the file ID as a query string parameter and outputs the file.
This resource would have no UI (remove everything from the .aspx except the Page directive) and would manually manipulate the response headers (this is where you'd set the content type from the file's type), write the byte stream to the client, and end the response. From the client's perspective, something like ~/MyContent/MyFile.aspx?fileID=123 would be the file. (You can suggest a file name to the browser for saving purposes in the response headers, which you'd probably want to do with the file's stored name.)
There's no shortage of quick tutorials (some several years old, it's been around for a while) on how to do this with images. Just remember that there's essentially no difference from the server's perspective if it's an image or any other kind of file. All the server needs to do is send the type in the response headers and write the file's bytes to the client. How the client handles the file is up to the browser. In the vast majority of cases, the browser will know what to do (display an image, display via a plugin a PDF, save a .doc, etc.).
I am working on an iPad app that is fed data via web service returning JSON. Watching some iTunes U episodes, it looks like sending back Plist would save me a ton of time and speed up my app quite a bit on the parsing side of things.
Does anyone know of a .net library that converts objects into this Plist to return instead?
EDIT (this is my very limited understanding of this topic):
An Plist is a Property List that iOS can use to easily encode and/or parse data. It is very similar to JSON except parsing takes a fraction of the time and can be done in 1 line of code. If your server uses WebObjects then encoding can also be done in 1 line of code, I am using IIS so I need a solution for this if one exists before I write my own.
You can see the videos here:
http://developer.apple.com/videos/wwdc/2010/
In particular watch Session 117 - Building a Server-Driven User Experience
You may checkout this project. Sample usage:
object value = ...
string plist = Plist.PlistDocument.CreateDocument(value);
The only requirement is to decorate your object with [Serializable] attribute.
If you're using WebObjects, the appserver from apple, there's a java mirror class of NSPropertyListSerialization that does all of this for you; you can pass it NSArray's, NSDictionaries, etc and it will just work. Not sure if that's what you're talking about; confused as to the WebObjects in your question. HTH's.
i use such code
string.Format("<img src='{0}'><br>", u.Avatar);
u.Avatar-it's like '/img/path/pic.jpg'
but in this site i can upload new image instead old pic.jpg. so picture new, but name is old. and browser show OLD picture (cache). if i put random number like /img/path/pic.jpg?123 then works fine, but i need it only ufter upload, not always. how can i solve this?
string imgUrl = _
string.Format("<img src='{0}?{1}'><br>", _
u.Avatar, _
FunctionThatLookupFileSystemForItsLastModified(u.Avatar).Ticks.ToString());
Instead of linking to the images directly, consider setting up a generic HTTP handler to serve the images.
MSDN: HTTP Handlers and HTTP Modules Overview
Stack Overflow: How to use output caching on .ashx handler
Append DateTime.Now.Ticks to the image url:
string imgUrl =
string.Format("<img src='{0}?{1}'><br>", u.Avatar,DateTime.Now.Ticks);
EDIT: I don' think this best practice are even a practice I would use. This is just a suggestion given the limited information given in case the Random implementation isn't truly Random.
Read your post again,,, sorry for general answer.
To workaround it do following
On Application_Start create a Dictionary with uploaded images save it on Application object, set it to null. Once you upload an image add it to this Dictionary. Wrap every place avatars appear on your website with function that evaluates image in Dictionary if found return imagename.jpg?randomnumber and then delete it from a Dictionary else return just an imagename.jpg.
This is going to be heavy because you will need to check each image in Dictionary but this will do exactly what you need.
You can set cache dependancy using the System.Web.Caching.CacheDependency namespace.
This can set the dependancy on the file uploaded, and will release the cache for that file automatically when the file changes.
There are lots of articles and stuff on MSDN and other places so I will not go into details on all that level of detail.
You can do inserts, deletes and other management of cache using the tools available.
(and this does not require you to change the file names or tack on stuff - it knows by the file system that the file changed)
The closest thing I could find was System.Net.Mime.MediaTypeNames but that doesn't seem to have everything (like json) since it seems to be more focused around email attachments.
An enum doesn't make much sense. MIME types are open-ended. That is, the list is not finite: new types are added from time to time.
See RFC4288: Media Type Specifications and Registration Procedures
In 2022, with .NET Core and .NET5+, this is now available via MediaTypeNames. For example:
MediaTypeNames.Application.Json
MediaTypeNames.Image.Png
MediaTypeNames.Text.Html
Microsoft documentation around MediaTypeNames, and each of Application, Image, Text.
https://learn.microsoft.com/en-us/dotnet/api/system.net.mime.mediatypenames?view=net-6.0
https://learn.microsoft.com/en-us/dotnet/api/system.net.mime.mediatypenames.application?view=net-6.0
https://learn.microsoft.com/en-us/dotnet/api/system.net.mime.mediatypenames.image?view=net-6.0
https://learn.microsoft.com/en-us/dotnet/api/system.net.mime.mediatypenames?view=net-6.0
https://learn.microsoft.com/en-us/dotnet/api/system.net.mime.mediatypenames.text?view=net-6.0
IANA's database is most likely to be complete. Currently, they have the list available in CSV format at https://www.iana.org/assignments/media-types/application.csv. I am assuming this is a stable URL whose content changes as updates are made. If you want to stay up to date, you'd need to put together a mechanism that is appropriate for your needs.
There is also the mime.types file that comes with Apache which seems to have been derived from the said list.
If like me you wanted to have no hard-coded string in your code you can use something like below
httpHeaders.add(HttpHeaders.CONTENT_TYPE,MediaType.APPLICATION_JSON_VALUE);
which is essentially
httpHeaders.add("Content-Type","application/json");