I am working on a website, where user can upload photos of product they want to advertise.
I am saving photos in a folder on the web. In the table where I keep reference of photos, there is a key field photoid which is Identity field(primary key).
My repository has following methods
Photo photo = rep.NewPhoto();
photo.Title="Some Title";
rep.InsertPhoto(photo);
rep.SaveAll();
rep.SavePhoto(photo,uploadedPhoto);
rep.SaveAll();
I am using Linq to SQL for my data model.
Now my problem is, if I want to save my files
with a name which is coming from photoid, I have to Call the rep.SaveAll()
method to get the new created photoid and then save the photo with new id
and then I have to Call SaveAll() method to update it again with the changes
happend in SavePhoto() method.
Other option is I save the file with some random file number first and then Save the photo record in one step.
This is second approach.
Photo photo = rep.NewPhoto();
photo.Title="Some Title";
string filename = rep.SavePhoto(uploadedPhoto);
photo.FileName=filename;
rep.InsertPhoto(photo);
rep.SaveAll();
Saving files with photoid has one good point, photos can be easily loaded using its id.
What is a good approach to achieve this kind of functionality.
Help will be appritiate.
Cheers
Parminder
Second approach is definitely more efficient; other option could be to create a unique in your application layer(you can use guids ) and then use this as key DB record and same as file name.
If you are using the latest SQL Server, you might want to look into the new FILESTREAM field type:
http://technet.microsoft.com/en-us/library/bb933993.aspx
It's for exactly this kind of thing -- trying to get large blobs out of the table structure and onto the filesystem.
Other than that, I think you have the right idea with either way you go -- if you need two saves, you might want to consider a transaction if you care about what happens if the second save or SavePhoto fails.
A couple of things:
1) Consider storing the photos as VARBINARY(MAX) in the database. It will be much easier for people to manage as far as backups and restores go, and it's better for your database's integrity.
2) Consider using the partial methods of your L2SQL Photo class in order to achieve what you want. You should be able to change your Photo class's Update method to save your photo as well. Hope this helps.
Related
Somehow in my firebase account 2 sets of data have changed the fieldname for 'DeviceID' to 'PeripheralID' and 'DeviceUUID'. Is there a way that I can search these and change them to be 'DeviceID'? I would prefer to do this by command line but will do whatever is easier.
Im thinking something along the line of firebase update:database ?
To answer the question with comments under question:
There is no tool for it. You'll have to download the data from database, edit JSON with some kind of text editor and upload it back to database.
This operation OVERRIDES information in database with information in JSON. In other words: uploading JSON changes database.
If you're using firebase console and data you want to change is not in whole database, you could open certain tree level and do those operation just there.
I'm developing a web application, Computerized Voting System using ASP.NET. i want to compare thumb impression from database. I'm using disconnected data access. is it possible to compare an input thumb impression with a thumb print already saved in SQL database? if yes then then how?
please describe some details of the application.
The images that are saved in the database, are they uploaded with the same application ? If so, you should add a new column where you will store the hash of the image.
You will have a table like this: |ID|ImageData|Hash|
This is how you can compute the hash:
string hash;
using(SHA1CryptoServiceProvider sha1 = new SHA1CryptoServiceProvider())
{
hash = Convert.ToBase64String(sha1.ComputeHash(byteArray));
}
Then, when you want to check if an uploaded image already exists in the database, you should compute the hash for it and send a query like:
string.Format("SELECT ID FROM Images WHERE Hash={0}", hash);
This will tell you if the exact same bytes are already in the database. If the image is similar, it will not work. It must be identical.
NOTE: you will have to convert your image into a byte array. This should not be a problem if you already do this when saving images in the database.
You might want to look in Computer Vision and Principal Component Analysis if you want to look for similarities between images.
We created special form to creating purchase prices for vendors.
New form has almost the same fields as original (so we used PriceDiscTable), but the record/datasoruce was set as temporary table. After user filled mandatory fields will click button, (extra logic behind) and record will inster to database (real priceDiscTable).
The idea was to grand access to trade prices for users that not necessarily has access to purchase prices. In theory everything was ok, but when user with no access to PriceDiscTable open new form, error was shown "Not enougt right to use table 'Price agreements'".
We try set the AllowCheck to false in formDatasource but this only allow us to open the form, but user still cannot add or modify records.
Is there any way to force system to allow user to write data in the temporary table?
Disabling security key or grand access to real table is not an option.
Duplicate table and create with same fields is nuisance (if we use same table we can use data() method to assign fields)
I think that creating a new temporary table with [almost] the same fields would be the best solution.
If the only reason you oppose to this approach is that you wouldn't be able to use data() to copy data from one table to another you can use buf2BufByName() as described here: http://mybhat.blogspot.co.uk/2012/07/dynamics-ax-buf2buf-and-buf2bufbyname.html
You can use RunAs to impersonate another user...perhaps a system user. I don't entirely follow what you are trying to do, but it sounds like this solution would work for you if you know exactly what your custom code is doing and is capable of.
See Classes\AifOutboundProcessingService\runAsWrapper to see an example.
You will not be able to display the PriceDiscTable without giving the user at least "view" access or editing Classes\FormRun to somehow bypass the security key, which is kernel level so it's also not possible.
I agree with 10p where you should create a temp table and then create a custom method handler combined with buf2bufbyname() or buf2buf().
Another option you can screw around with, if you REALLY want to use .data() is using a Common as the datasource. You could add the fields you want on the grid with the common, then you can pass a common back/forth. This has a good amount of form setup to get this working, but it could produce what you want eventually I think.
static void Job8(Args _args)
{
Common common;
salesTable salesTable;
;
common = new DictTable(366).makeRecord();
select firstonly common where common.RecId == 5637145357;
salesTable.data(common);
info(strfmt("%1 - %2", salesTable.SalesId, salesTable.SalesName));
}
I am using GridView in asp .net and editing data with edit command field property (as we know after updating the edited row, we automatically update the database), and I want to use transactions (with begin to commit statement - including rollback) to commit this update query in database, after clicking in some button (after some events for example), not automatically to insert or update the edited data from grid directly to the DB...so I want to save them somewhere temporary (even many edited rows - not just one row) and then to confirm the transaction - to update the real tables in database...
Any suggestions are welcomed...
I've used some good links, but very helpful, like:
http://www.asp.net/learn/data-access/tutorial-63-cs.aspx
http://www.asp.net/learn/data-access/tutorial-66-cs.aspx
etc...
Well,
you can store your edited data in a DataTable in session. and then pass this data table as a bulk insert in to the database. 2 options are available for this
if you are using SQL Server 2005 you can use OpenXML to achieve this, as i have stated here
if you are using SQL Server 2008 youc an use Table Variables like i did here.
i hope it helps
First way:
Create session variable that will contain your DB object (DataTable or mapped objects).
The GridView should work with this instance instead of sending the data to the database.
Once editing is finished you may take the object from the session and save it in the way you normally do.
Second way:
I would use javascript to collect all changes on the client side while he is editing as a array of objects (each object is separate row).
Once the editing done, you can create json string from the collection and pass it to the server.
If your json object configuration is same as server class then you can use JavaScriptSerializer to deserialize your string into collection of object.
After that, you can save your objects in the way you normally do.
I need a place to store images. My first thought was to use the database, but many seems to recommend using the filesystem. This seems to fit my case, but how do I implement it?
The filenames need to be unique, how to do that. Should I use a guid?
How to retrieve the files, should I go directly to the database using the filename, make a aspx page and passing either filename or primary key as a querystring and then read the file.
What about client side caching, is that enabled when using a page like image.aspx?id=123 ?
How do I delete the files, when the associated record is deleted?
I guess there are many other things that I still haven't thought about.
Links, samples and guidelines are very welcome!
Uploading Files in ASP.NET 2.0
You seem up in the air about how to do this, so I'll give you a few ideas to get you going.
If you want to use a file system make sure you know the limit of how many files are permitted per directory, so you can set up a system that creates subdirectories. http://ask-leo.com/is_there_a_limit_to_what_a_single_folder_or_directory_can_hold.html
I would make a table something like this :
FileUpload
UploadID int identity/auto generate PK, used as FK in other tables
InternalFileName string
DisplayFileName string
Comment string
MimeType string
FileSizeBytes int
FileHash string MD5 Hash of a File
UploadUserID int FK to UserID
UploadDate date
You would include the UploadID in the table that "owns" this upload, like the Order associated with it, etc. You could add the InternalDirectory column, but I prefer to calculate this based on a constant Root value + some key specific value. For example, the complete file name and directory would be:
Constant_Root+'\'+OrderID+'\'+InternalFileName
You could make the InternalFileName be the UploadID and the file extension from the original file. That way it would be unique, but You'll have to insert the row as the first part of the process, and update it after after you know the file name and identity/auto generate row value. You could make the InternalFileName something like YYYMMDDhhmissmmm and the file extension from the original file, which may be unique enough based on how you use subdirectories.
I like to store a MD5 Hash of a File which makes detecting duplicates easy.
MimeType and FileSizeBytes can be found from the file system, but if you store them in the database, it makes some maintenance easier since you can query for large files or files of certain types.