I'm building an application that takes as an input data stored in an Excel sheet. I want the user to be able to select the file they want to load data from, have the application connect to and read from the Excel file stored on the client's machine, and close the connection. Can I do this without uploading the Excel file to the server? I'm able to do everything except for selecting the file using a filedialog box and passing the path & file name to the procedure that connects to the Excel file and processes. I've tried using the file input control but I'm unable to pass the path & file name to the connection string. Any suggestions as to what other routes I might take?
EDIT:
The application essentially takes user input, either via single inputs into textboxes on the page or a bulk upload via an Excel spreadsheet, processes the inputs and spits out a report in Excel format. The only thing displayed on the page are the loaded inputs (via the 2 methods just described) in a listbox that the user can either add or remove additional items.
The short answer is "Only with an ActiveX control in IE unless you write your own plugin for another browser." My opinion is, "you shouldn't."
There is a good discussion already on Stack Overflow: How to read an excel file contents on client side?
The long answer, given the rest of the information you have provided, is that I would recommend the following:
1) Upload the spreadsheet to the server.
2) Extract the data on the server.
3) Return the data to the client in whatever form suits your situation.
4) Clean the original file on the server.
Some further recommendations for you, since you provided so much detail in your comments:
Rather than using a GUID to generate your server-side filename, use a timestamp in the format YYYY-MM-DD-HH-MM-SS-Ticks followed by the original filename.
Instead of deleting the data files immediately, each time you add a file, remove any files older than N days.
This way if you have any issues processing your files in the future, you'll be able to retrieve the uploaded file to your development environment and debug it there. Assuming the data isn't personal information or sensitive in some other way, of course.
Cheers!
Related
I am writing a PLSQL procedure that takes input as an excel file through front end and using that excel input the procedure inserts , updates or deletes the records present in an existing table . Can anyone show me the approach for this?
If that "Excel" file has to be really in native XLS(X) format, a simple option - if you want to stay within Oracle boundaries - is an Apex application which offers a data loading wizard. Takes 4 pages to create it (don't worry, Apex Wizard creates almost everything for you). Once the loading is over, a (stored) procedure can do the rest of processing (you'd call it by pushing a button).
Alternatively, if you save contents of that file as a CSV file, you can load it with SQL*Loader, utility ran at the operating system command prompt. You'd have to create a control file (no wizard to do that, I'm afraid). This approach probably isn't convenient for end users (who's going to type anything at the command prompt?) so you'd have to create some kind of an application to do that.
Or, CSV again, but this time used as an external table. This approach requires the file to be located in a directory accessible by the database server (most frequently, the directory is located on that computer, and you most frequently don't want to allow access to anyone to it). Its advantage is that you can access the CSV file directly from (PL/)SQL, fetch data from it, perform various adjustments etc.
If you're capable of writing programs that aren't part of the Oracle niche (I'm not), go for it (but I can't suggest anything; someone else might).
i'm asp.net beginner and currently working in "upload download file" project with asp.net and vb.net as code behind language (like skydrive's web).
what i'm want ask is about upload file in server, must we store path file, size, accessed or created date into database? as we know we can use directory listing in system.io.
Thanks for your help.
You definetly want to store the path of the file. You want a way to find the file ;) Maybe later you will have multiple servers, replication or other fancy things.
For the rest, it depends a bit on the type of website. If it's going to get high traffic then store it in the database, this will limit the number of IO call (very slow). Also, it'll be a lot easier to handle sorting and queries. (sort by date, pull only the read onyl files, ...).
Database will also help if you want to show history or statistique.
You can save file in some directory and can save path of that file in database. You can also store size and created date of that file in DB. But storing a file in DB is a bit difficult. Rather than save file in Directory and save path of that file in DB
you could store the file information in a database to built some extra features like "avoid storing duplicate files", because you are having a faster search in the database! if you search the filesystem always a recursive function call get started
I have a .jpg file which represents the current image from a webcam. User's will be downloading this file at an interval of once a second. Because there could be dozens of users reading it, this could be dozens of times a second (which is normal for any web server).
Problem is, this image is updated by a 3rd party application also once a second which "spiders" my local networks webcam portal image. This is so we can build our webcams into our current administration panel.
The problem I am already finding is ASP.net sometimes gets an error it can not access the file because it is open for write permissions by the bot. Likewise, the bot can not access it because IIS is feeding it to the user.
The bot uses io.streamwriter to save the data to the file, and my script uses Response.WriteFile to send the file to the script. (I need to use an actual ASP.net page with a JPG content-type that feeds the file to make sure only users with a active session can view the JPG).
My question is what is the best practices for this? I know why it's happening but what is the best resolution for this? Would storing as a BLOB in a database maybe be smarter since databases are created for concurrent read/writing already? Is there an easier way of doing this with a file I have not thought of yet?
Thanks in advance,
Anthony Greco
Using a BLOB will work if the readers use SNAPSHOT isolation model (SQL Server 2005 and up). See Download and Upload images from SQL Server via ASP.Net MVC for how to stream an image from a BLOB, and see Understanding Row Versioning-Based Isolation Levels for a lecture on SNAPSHOT.
But using a BLOB may be overkill, you could get away with something much simpler. For instance, if you only have one ASP.Net process, then you could have a global volatile variable for the current file name. The writer writes the JPG into a new file, and then updates the global 'current' file name with an Interlocked.CompareExchange operation (it has to be Compare because a newer writer might actually finish faster, outrun a previous writer, and you want to preserve the latest update). There are still some issues left to solve (find out the file name at startup, clean up old files etc) but they are all fairly ease to solve.
If you have a farm of servers, or multiple ASP.Net processes serving the site, then things could get complicated. I would still do a rotating file name and do a try-and-error approach (try to respond with newest file, fall back to previous older one if conflict is detected).
You could get the bot to write the data to a different filename and then do a delete and rename to the filename being served by ASP.Net. This should reduce the file lock time down to the time for a delete and rename to occur. To clarify:
ASP.Net serving image from "webcam.jpg"
bot writes image data to "temp.jpg"
when last image byte written, bot deletes "webcam.jpg" and renames "temp.jpg" to "webcam.jpg"
ASP.Net should check "webcam.jpg" exists, if not wait 10ms (or suitable small increment) and check again.
I'm coding in ASP.NET and want to store audio files (.mp3, or smaller formats) in a MySQL database; which, I can then retrieve based on certain conditions. Is this possible? Are there any preferred methods to having Audio files on your web pages (besides embedding them in the HTML).
Most solutions that store files in a database do not scale well, but you can certain store audio files, or any other type of file, as a blob (binary large object) in MySQL. You can create an ashx handler that performs the retrieval from the database and writes the content to the ASP.NET output stream as raw binary data. You can then create links that point to the ASHX handler and perform any query logic you want in there based on URL parameters.
If you are using a MySQL database, it seems to do well (at least in my experience) with blobs. It takes a relatively short time to load the MP3 and if you tune your database for audio, you can probably even get better performance (I pretty much use default settings).
One thing to remember is that you define the MIME-type so that users know what they are getting when they click a link to access your MP3.
Again, all of this is my own experience. YMMV.
I prefer to store large files outside of the database, unless there is some overwhelming need to keep everything there.
You could store the location of the file in the database and have the files outside of the webapp directory, so they can't be accessed directly.
Then, in the url for playing the music you can just have a cgi program that will just send that data to the browser, with the correct mime type.
i need to generate an excel sheet from an excel template which contains drop down lists. I need to use the template and populate the with data from datbase and select the appropriate value from the drop down lists and generate the new excel sheet. I am in very bad situation and need it asap.
try spread Sheet Gear third party component
http://www.spreadsheetgear.com/
OR
http://www.smartxls.com/
You have a few options:
Third-party component ($$$) to read, modify, and send the Excel file.
Office COM automation on the back-end (bad idea. Really. Don't do it).
Save your template on the server as an XML Spreadsheet file (the XML format used by Office 2002 and 2003 and still supported in 2007). Since it's a single XML file, it can be easily read by server-side code, modified on the fly, and redirected back to the user.
Save your template on the server as an XLSX file (the newer XML format used by 2007) and modify it on the way out to the user. Much more complicated since there's a ZIP wrapper and multiple XML files involved.
Save your template on the server as a normal Excel 97/2000 file (not 2007), and when the user requests it, make a copy of the file on the server (requires write access) with a random name, open an database connection using the Excel OLEDB driver to the Excel file, perform INSERT statements into it (goes into tabs of those names, where you store your drop-down values), close the connection, and send the file. Caveat: the Excel OLEDB driver has some limitations.
Go the other direction. Use Excel's web data connection capabilities to access the server after the Excel file is already on the user's machine and open to grab the appropriate values from the server. Requires some user training to refresh the data.