GetRandomFileName to generate a file name without a path. In the following example, the path is obtained from configuration:. The path passed to the FileStream must include the file name. If the file name isn't provided, an UnauthorizedAccessException is thrown at runtime. Files uploaded using the IFormFile technique are buffered in memory or on disk on the server before processing. Inside the action method, the IFormFile contents are accessible as a Stream. In addition to the local file system, files can be saved to a network share or to a file storage service, such as Azure Blob storage.
GetTempFileName throws an IOException if more than 65, files are created without deleting previous temporary files. The limit of 65, files is a per-server limit. For more information on this limit on Windows OS, see the remarks in the following topics:. To store binary file data in a database using Entity Framework , define a Byte array property on the entity:. Specify a page model property for the class that includes an IFormFile :.
IFormFile can be used directly as an action method parameter or as a bound model property. The prior example uses a bound model property.
Use caution when storing binary data in relational databases, as it can adversely impact performance. The examples provided don't take into account security considerations. The 3. The file's antiforgery token is generated using a custom filter attribute and passed to the client HTTP headers instead of in the request body. Because the action method processes the uploaded data directly, form model binding is disabled by another custom filter.
Within the action, the form's contents are read using a MultipartReader , which reads each individual MultipartSection , processing the file or storing the contents as appropriate.
After the multipart sections are read, the action performs its own model binding. The initial page response loads the form and saves an antiforgery token in a cookie via the GenerateAntiforgeryTokenCookieAttribute attribute.
The attribute uses ASP. NET Core's built-in antiforgery support to set a cookie with a request token:. ConfigureServices using Razor Pages conventions :. Since model binding doesn't read the form, parameters that are bound from the form don't bind query, route, and header continue to work. The action method works directly with the Request property. A MultipartReader is used to read each section. After the multipart sections are read, the contents of the KeyValueAccumulator are used to bind the form data to a model type.
The complete StreamingController. UploadDatabase method for streaming to a database with EF Core:. UploadPhysical method for streaming to a physical location:. In the sample app, validation checks are handled by FileHelpers. The sample app's FileHelpers class demonstrates a several checks for buffered IFormFile and streamed file uploads.
For processing streamed files, see the ProcessStreamedFile method in the same file. The validation processing methods demonstrated in the sample app don't scan the content of uploaded files. Although the topic sample provides a working example of validation techniques, don't implement the FileHelpers class in a production app unless you:.
Never indiscriminately implement security code in an app without addressing these requirements. This tells ASP. For more information, see Introduction to ASP.
On your development computer this is not typically an issue. However, when you publish your site to a hosting provider's web server, you might need to explicitly set those permissions.
If you run this code on a hosting provider's server and get errors, check with the hosting provider to find out how to set those permissions. In the previous example, you used WriteAllText to create a text file that's got just one piece of data in it. If you call the method again and pass it the same file name, the existing file is completely overwritten.
However, after you've created a file you often want to add new data to the end of the file. You can do that using the AppendAllText method of the File object. In the website, make a copy of the UserData. This code has one change in it from the previous example. The methods are similar, except that AppendAllText adds the data to the end of the file. Even if you don't need to write data to a text file, you'll probably sometimes need to read data from one.
To do this, you can again use the File object. You can use the File object to read each line individually separated by line breaks or to read individual item no matter how they're separated. This procedure shows you how to read and display the data that you created in the previous example. The code starts by reading the file that you created in the previous example into a variable named userData , using this method call:. The code to do this is inside an if statement. When you want to read a file, it's a good idea to use the File.
Exists method to determine first whether the file is available. The code also checks whether the file is empty. The body of the page contains two foreach loops, one nested inside the other.
The outer foreach loop gets one line at a time from the data file. In this case, the lines are defined by line breaks in the file — that is, each data item is on its own line. The inner loop splits each data line into items fields using a comma as a delimiter. Based on the previous example, this means that each line contains three fields — the first name, last name, and email address, each separated by a comma. The code illustrates how to use two data types, an array and the char data type.
The array is required because the File. ReadAllLines method returns data as an array. The char data type is required because the Split method returns an array in which each element is of the type char. For information about arrays, see Introduction to ASP. You can use Microsoft Excel to save the data contained in a spreadsheet as a comma-delimited file. When you do, the file is saved in plain text, not in Excel format.
Each row in the spreadsheet is separated by a line break in the text file, and each data item is separated by a comma. You can use the code shown in the previous example to read an Excel comma-delimited file just by changing the name of the data file in your code. Jiang Software Developer Senior www.
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Software Developer Senior www. First Prev Next. Click on the Invoke button, and you'll see the base64 encoded string of the file contents. Set the Output Directory to the same directory as your Web service virtual root and then generate the proxy. Create a new ASP. NET Web page. Add the following code to your new page:. SaveAs filename ; System. BinaryReader System.
Open filename, System. Open, System. Read ; FileIO. FileRW ; frw. DefaultCredentials; br. Write br. ToInt32 br. Length ; br. Close ; frw. PutFile buffer, file1. Substring file1. You'll probably have to adjust the permissions in your web. Also, it's important to notice that if you choose to impersonate, which is how I set up my local server, you need to pass the authenticated credentials along to the Web service.
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