Skip to main content

Use TempData Keep or Peek method to persist data in MVC

TempData used to transfer data between controllers or between actions. There is one point to note that TempData is only work during the current and subsequent request and it is generally used to store one time message.
But one can persist data in TempData object even after request completion with the help of Keep() or Peek() method.

TempData.Keep(): TempData.Keep() method keep value in TemData object at the end of current request. There are two overloaded keep methods available with TempData:
·         void Keep(): This method make ensures that all the items in TempData are not destroyed on current request completion.
·         void Keep(string key): One can persist the specific item in TempData by passing in the item name.

TempData.Peek(string key): It returns an object that contains the element that is associated with the specified key, without marking the key for deletion.

//Set some value to TempData
TempData["value"] = "some value";

//Get value from TempData and marking TempData for deletion.
var val = TempData["value"];

//Decide to retain the value.
//Keep all items.

//Keep specific item named as value.

//Read and retain value at the end of the request in a single request using Peek.
val = TempData.Peek("value");

Difference between Keep() and Peek() method: Both method used to retain the value at the end of request and if you are wondering what is the difference then here it is:
Keep Method
Peek Mthod
To read and retain the value with Keep one need to do two request, i.e. first read the value and in next statement call Keep method to retain value.
With the help of Peek method one can do both operation in a single statement i.e. access as well retain value.
Keep method can be overloaded, i.e. one can keep all items or pass the key to retain specific item.
There is no overloaded method in case of Peek method.
RedirectResult and RedirectToRouteResult internally calls Keep method to retain items
Peek method is not called internally with any of ActionResult.

Popular posts from this blog

C#: Merging Excel cells with NPOI HSSFWorkbook

In this post we’ll see how to merge the two or more cell with each other while creating the excel sheet using NPOI.
Mentioned below is code to merge multiple cells, in this example we are merging first cell to fifth cell of first row (you can adjust row or cell range by passing particular parameters in CellRangeAddress).
//Created new Workbook var hwb = new NPOI.HSSF.UserModel.HSSFWorkbook(); //Create worksheet with name. var sheet = hwb.CreateSheet("new sheet"); //Create row and cell. var row = sheet.CreateRow(0); var cell = row.CreateCell(0); ; //Set text inside cell cell.SetCellValue("This is Merged cell"); cell.CellStyle.WrapText = true; //define cell range address // parameters: -> first row to last and first cell to last cell var cra = new NPOI.SS.Util.CellRangeAddress(0, 0, 0, 4); //Add merged region to sheet. sheet.AddMergedRegion(cra);
Hope this solution helps you J

Read and parse a CSV file into an array of rows and columns in C#

The following PopulateCsvIntoArraymethod used to read the CSV file into a two-dimensional array of strings.
I have included explanation of method lines, wherever needed. ///<summary> /// Populate the CSV file into an array, /// We assume that every line has the same number of fields and there may be blank lines. ///</summary> ///<returns></returns> privatestring[,] PopulateCsvIntoArray() { // Get path of CSV file. var path = Server.MapPath("~/Folder_Name/testfile.csv"); // Get the file's text using ReadAllText method. string fileData = System.IO.File.ReadAllText(path);
// Split CSV data into lines.     fileData = fileData.Replace('\n', '\r'); string[] lines = fileData.Split(newchar[] { '\r' }, StringSplitOptions.RemoveEmptyEntries);
// Get rows and columns counts. int totalRows = lines.Length;

Calculate Sum and average of two or more Textbox values using JQuery

We can calculate sum and average of values entered in textboxes with the help of small piece of jQuery code.
First of all let’s create a HTML form where we’ll ask user to enter marks in each subject, under body section add following HTML:
<tableclass="demo-table"> <trclass="label"> <tdcolspan="2">Please enter marks(0-99):</td> </tr> <tr> <td>English</td> <td> <inputtype="text"class="txtMarks"name="txtMarks"