I made an amateur winform, which saves data from textboxes to a shared excel workbook in a first blank row of a specified worksheet. This winform is present on 3 PC's and the workbook is reachable on dropbox. In my situation I cannot make a shared folder instead of dropbox, because the network is a huge one + password protected and I won't get to know it, so the only "shared folder" alternatives are stuff like Dropbox.
Sometimes users need to open the workbook and write&save some data manually. This case gives additional "conflicted copy" files (because dropbox is incompatible of merging information of 2 simultaneously altered files).
If i could somehow make the excel file to be available to only one user at a time - this would make the winform crash on buttonclick if the workbook is open on any other PC.
The excellent goal would be enabling changes the workbook both by the winform and manual input and not getting any conflicting changes choices by excel and conflicted copy files on dropbox.
Any ideas? Thx in advance!
In all honesty, i think you would be better off making your users use a shared google docs spreadsheet, that they can all alter at the same time. You can use many different sheets to prevent confusion or data corruption.
Or if you really need to use a winform, save the data to ( and load from ) a sql express DB, which was made for small multiuser applications. Winforms can link to MS sql express really easily.
Related
I have to load huge amount of data, pre-process it, share it among few users and finally gather updates back from users.
This is what I did in my previous project -
Created an excel add-in using C++. Loaded the data in memory using the add-in code and processed it. For each type of data I have sent the processed data to a sheet and saved a new excel file. That way, if I have three types of data, I have created three new excel workbooks. My users then opened those new workbooks, made their changes and dropped a text file that contains their changes (through a button). The main excel keeps polling for those updates (text files) and loads them as soon as they are found. That's the way I get the updates back from my users.
I am not a fan of what I did in my previous project, it produces too many temporary files (of course I can delete those). In my current project I want to use C# VSTO Workbook so I can have more control over excel. I was hoping once I load the data, I will ask my users to open the same excel in Read-Only mode and they will make changes. While testing this, I realized user's excel (opened in read-only) mode does not see the loaded data. And their changes do not update the data held in memory. This probably means I have no idea what I am doing.
Do you guys have any idea how to achieve this? I will really appreciate any help/hint.
Excel supports so-called "co-authoring" mode, when many people can edit the same document at the same time. But there is might be a catch: afaik, you need a Share Point/Office Online server/OneDrive Business to support this scenario (you need a non-free office document server product).
Using VSTO, you can do just the same you have done with C++ add-in, but in C# (means, the set of capabilities is 1:1 - it basically just wraps C++ COM Excel API for .NET)
But for online version of Excel, there may be yet another alternative - javascript addins (now that's called "Office Addins", afaik). But I doubt you'd want to process your "huge amounts of data" with javascript.
So I would say, there is a good rule: Don't fix something that isn't broken :)
If the problem is the number of temporary files, these files is not the only option to transfer data between applications. You know, you can connect two applications directly (so that they can exchange data with messages/updates). Use network, Luke :)
Of course if your 3 users live on 3 deserted islands, totally disconnected from anything, exchanging with text files on USB stick may still be the only viable option...
I think the "web" solution could be: store your file in some "co-authoring"-capable service (sharepoint, google shees, onedrive, officeonline, whatever). Make some web job to update that file in that storage automatically. Just like a "fourth" user would do.
folks,
Environment
Windows 8.1
Visual Studio 2013
C#
Issue
How do I write values and make charts on visible Excel sheets using NPOI (https://npoi.codeplex.com/).
Why do I want that?
I'm developing an application to measure temperature in an apparatus. To put together experimental data in one place, I'd like to record data on an Excel sheet and make a chart on the sheet. In addition, I'd like to keep the Excel sheet visible and check the chart updated in real time.
You could also make graphs on Windows Form apps with MeasurementStudio by NationalInstruments for example but considering the flexibility of Excel charts (size and xy range changeable, easy-to-use user interface, etc...), I'd like to stick to Excel.
You can easily do this with Microsoft.Office.Interop.Excel by
ExcelApp.visible = true;. However, this module requires users to release every COM object generated. Otherwise, the objects remain and eat up memory. This is the reason I prefer to use NPOI.
How can I achieve this? Any answers would be appreciated.
You cannot do this with NPOI. NPOI reads and writes data from serialized Excel files. You cannot access those files while Excel has them open, and even if you could, Excel simply wouldn't re-read the files so your modifications wouldn't show up.
The problem you describe comes down to "I want to interact with a running Excel instance without using Excel interop". That's not going to work.
Need to create a application in C# with Win Forms the applications need to do the following:
1.Open a excel workbook in the background the user should not see this step
2. Then save the data in some way to the application so it can be accessed later
3. Receive a 8 digit identification code from a text box and search for a entry in the excel workbook containing the same digit
4.When the relevant entry is found the application should write the current time and date to a cell Sign-In and at the specific date the entry is done.
5. The application should then save the workbook automatically and
6.Then close the application.
Can anyone help me please the Microsoft.Office.Interop is very complicated.
Try closedXML, it sits on top of Excel Interop and makes things easier.
But with out any examples of what you have tried it is really hard to tell you how to accomplish what you want.
If you don't have old-excel support (.xls), you can use Wrapper.OpenXml which available as Nuget package.
Hello
My application from the stockbroker has this button called "Start excelfeed" which opens an excel file and then updates the incoming prices in realtime. I want these prices extracted into my application (Java), but after several tries with jxl and poi ive found out it only extracts the values which occurred last time i saved the excel files. Are there any possible ways to extract these prices in real time? I'm not sure which method theyre using to feed the excel file, except their app is written in C#.
You can have a look at the VBA code behind the "Start excelfeed" button by hitting Alt+F11 ... Then you can check how the excel macro taps into the data source und try to adapt that in Java
[EDIT]
#Zico Sorry then I got you wrong. In that case I'd try to automate it via the Java Robot Class like user489041 suggested or you could fire up wireshark and try to snoop around the network traffic
They are using the DDE technique and you should use excel automation to pull data from excel into your app.
In the old days, we used DDE links. Chances are your stockbroker addin uses precisely that.
Chances of using DDE from java are pretty slim (close to zero) because it is windows specific. However, possibly there are other methods involved (like COM components or TCP/IP connection). I'd suggest you get the values from teh stockbroker source like the Excelfeed, instead of going through Excel.
Of course, the problem with that is that you won't get help from the vendor of the Excel addin. If things are like they were 8 years ago, they are making tons on your buying the Excel addin and don't really want to help you program against that :)
Worst case, you could use the Java Robot class to create the Excel spreadsheet, save the Excel spreadsheet as a CSV file, then read the CSV file from your Java program.
You can do this with solutions like Obba. Obba allows to access a Java virtual machine running the "Obba Server" directly from Excel.
For your problem, you have to "create" your application from the spreadsheet (load the jar, create an object representing you app - e.g. launching it in a separate thread). Then you can feed the app from Excel... - In this case, Excel is to some extend the "control program" of your app. However, if you start the Obba Server process manually, the process will keep on running if you close and re-open Excel.
I have huge excel files that I have to open from web browser. It takes several minutes to load huge file. Is it possible to open a single worksheet (single tab) at a time from excel file that contains many worksheets? I have to do this using C# / asp.net MVC
I'm assuming you have the excel workbook on the server and just want to send a single worksheet to the client. Does the user then edit the worksheet? Will they be uploading it back?
Assuming this is just a report then why not use the OpenXML sdk to read the workbook, extrac the sheet in question and send it back to the client? This is what #Jim in the comments was suggesting. You can get the SDK here: Open XML SDK 2.0 for Microsoft Office . However, I'm not sure if it will work with the 'old' excel format. I assume you'll need to save the template workbook in the new Office formats (xslx).
Your question is slightly unclear as to where the spreadsheet is stored.
If it's on a server you control, process it, extracting sheets you need, and create other sheets which are smaller in size. (Or possibly save them in a different format.).
If they're not on a server you control, download the file using C#, then go through a similiar process of extracting the sheet before opening it.
Having said that, I've dealt with some largish spreadsheets (20MB or so), and haven't really had a problem processing the entire spreadsheet as a whole.
So where is the bottleneck? Your network or possibly the machine you're running?
Use third party components.
We are fighting with server side Excel generation for years and has been defeated.
We bought third party components and all problems gone.
From your question, it seems you want to improve load time by using (opening) the data from one worksheet instead of the whole workbook. If this is the case and you only want the data, then access the workbook using ADO.NET with OLEDB provider. (You can use threading to load each worksheet to improve load performance. For instance, loading three large data sets in three worksheets took 17 seconds. Loading each worksheet on a separate thread, loaded same data sets in 5 seconds.)
From experience, performance starts to really suffer with workbooks of 40MB or more. Especially, if workbooks contain many formulas. My largest workbook of 120MB takes several minutes to load. Using OLEDB access, I can load, access, and process the same data in a few seconds.
If you want the client to open data in Excel, gather data via ADO.NET/OLEDB, get XML and transform into XMLSS using Xslt. Which is easy and there is much documentation and samples.
If you just want to present the data, gather data via ADO.NET/OLEDB, get XML and transform into HTML using Xslt. Which is easy and there is much documentation and samples.
Be aware that the browser and computer become non-responsive with large data sets. I had to set limit upper limit. If limit was reaced, I notified user of truncated results, otherwise, user thought computer was "locked".
Take a look at this question in StackOverflow:
Create Excel (.XLS and .XLSX) file from C#
I think you can open your workbook on the server (inside your ASP.NET MVC application) and process only the specific worksheet you want. You can then send such worksheet to the user using NPOI.
The following post shows you how to do that using an ASP.NET MVC application:
Creating Excel spreadsheets .XLS and .XLSX in C#
You can't "say" to Excel, even via Interop that you only want a single worksheet. There are a lot of explanations, like formulas, references and links between them, which makes the task impossible.
If you only want to read the data from the worksheet, maybe OLEDB Data Provider is the best option for you. Here is a full example: Reading excel file using OLEDB Data Provider
Otherwise, you will need to load the entire workbook in memory before do anything with it.