AddWithValue " Data" , bytes ;. Open ;. ExecuteNonQuery ;. Close ;. Redirect Request. AbsoluteUri ;. Using br As New BinaryReader fs. ReadBytes DirectCast fs. Length, Long.
ConnectionStrings "constr". Using con As New SqlConnection constr. Using cmd As New SqlCommand query. Add " Name" , SqlDbType. Add " Data" , SqlDbType. End Using. End Sub. Net GridView. Below is the code which populates the ASP. Net GridView from files saved in the database table. BindGrid ;. ExecuteReader ;. DataBind ;. End If. Private Sub BindGrid. Using cmd As New SqlCommand. Parse sender as LinkButton.
CommandArgument ;. Parse TryCast sender, LinkButton. As soon as the page is rendered the Generic Handler will be called and using the ID from the QueryString it will fetch the File data, i. Name, Content Type and the Byte Array is fetched from the database. Once the data fetching process is completed the file is sent to the browser for downloading using the Response Stream.
Note: If the Adobe Reader is not installed in the system, User will not be able to view the files and in such scenario, I have given users option to download the file and hence an additional QueryString parameter download is passed so that the PDF file is downloaded as attachment. Excel, is most easily achieved using our NuGet package, although you may also choose to manually install the DLL to your project or to your global assembly cache.
Additionally, you can view the package on the NuGet site here. Alternatively, we can start by downloading the IronXL. The WorkBook class represents an Excel sheet. Load and specify the path of the Excel file. Each WorkBook can have multiple WorkSheet objects. These represent worksheets in the Excel document.
If the sheet contains worksheets, retrieve them by name WorkBook. Each "WorkBook" can have multiple WorkSheets. This is how one workbook with two worksheets looks in Excel.
To create a new WorkSheet call WorkBook. CreateWorkSheet and pass the name of the worksheet. The "Range" class represents a two-dimensional collection of "Cell" objects. It represents a literal range of Excel cells. Obtain ranges by using the string indexer on a WorkSheet object. The argument text is either the coordinate of a cell e. It is also possible to call GetRange on a WorkSheet.
There are several ways to read or edit the values of cells within a Range. If the count is known, use a For loop. Use IronXL to validate a sheet of data. The DataValidation sample uses libphonenumber-csharp to validate phone numbers and uses standard C APIs to validate email addresses and dates. The above code loops through each row in the spreadsheet and grabs the cells as a list.
Each validates method checks the value of a cell and returns an error message if the value is invalid. This code creates a new sheet, specifies headers, and outputs the error message results so that there is a log of invalid data. Use IronXL to export data to a database or convert an Excel spreadsheet to a database. To use a different database, install the corresponding NuGet package and find the equivalent of UseSqLite. Create a CountryContext , iterate through the range to create each record, and then SaveAsync to commit data to the database.
Set formula of Cell 's with the Formula property. The following code iterates through the countries and sets the Name, Population, Region, NumericCode, and Top 3 Languages in the spreadsheet.
In addition, there are other tutorials which may shed light in other aspects of IronXL. Excel is alone.
Hopefully they will make the Core 3. Depending on how the issues are resolved, the resulting behavior might be like ConcurrentDictionary: a race condition may lead to multiple values being created, but only one value is ever stored and returned. If it is truly undesirable to create a value multiple times and often it does not really matter, as a one-time cost! You fixed concurrent issue using dictionary of SemaphoreSlims.
You can optimize it a bit: 1. Awesome Maxim, thanks for this reference! Great article! Was this updated to prevent unlimited growth.. That was the first thing that came to mind when I saw that extra ConcurrentDictionary in the code. Good post! I was looking for a memory cache implementation to attach it in a repository pattern. The truth is that seeing the code seems an elegant way to solve the problem of concurrence in memory access. In case it helps. I agree that callback can be a good place for cleanup.
And thanks! When should the cache be used as a singleton or scoped DI instance and what are the factors to consider? If creating the cache as a singleton if its used with any data layer that is scoped that would not work but is there performance issues if a concurrent dictionary is scoped where it would recreate the cache in memory each time? You can decouple your memory cache from your model and still have implemented an async method.
Result ; return Request. CreateResponse System. Forgot to mention: You have to implement your own equals override for your param object! Skip to content One of the most commonly used patterns in software development is Caching. In-process Cache, Persistant in-process Cache, and Distributed Cache There are 3 types of caches: In-Memory Cache is used for when you want to implement cache in a single process.
When the process dies, the cache dies with it. Persistent in-process Cache is when you back up your cache outside of process memory. It might be in a file, or in a database. This is more difficult, but if your process is restarted, the cache is not lost. Best used when getting the cached item is expansive, and your process tends to restart a lot. Distributed Cache is when you want to have shared cache for several machines.
Usually, it will be several servers. With a distributed cache, it is stored in an external service. This means if one server saved a cache item, other servers can use it as well. Services like Redis are great for this. ContainsKey key. GetAvatar userId ;. TItem cacheEntry ;. Set key , cacheEntry ;. SetPriority CacheItemPriority. SetSlidingExpiration TimeSpan. FromSeconds 2. SetAbsoluteExpiration TimeSpan.
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