Sometimes you need to manually trigger an update of the information in fields like those used in a table of contents, headers and footers, cross-references, bookmarks, and formulas in tables.
You can update fields one by one, or you can update all the fields in your document at once. Update a field. Update all fields in a document. In a document you have open, right-click a field, such as a table of contents, a page number, or a cross-reference, and click Update Field. Updating page numbers only simply updates the page numbers for the existing sections. To update your table of contents with new sections from your document, select Update entire table. If your document has tables with fields or formulas, you might need to select each table separately and press F9.
Note: Sometimes a field is not updated because the item the field refers to no longer exists. If the GridView's view state is disabled, however, on each postback the GridView's data is rebound to its underlying data source, which causes the Calendar's selected date to be set back to the employee's HireDate , overwriting the date chosen by the user. For this tutorial this is a moot discussion since the user is not able to update the employee's HireDate.
It would probably be best to configure the Calendar control so that its dates are not selectable. Regardless, this tutorial shows that in some circumstances view state must be enabled in order to provide certain functionality. A third use of TemplateFields is in displaying metadata about the GridView's underlying data.
In addition to showing the employees' hire dates, for example, we might also want to have a column that displays how many total days they've been on the job. Yet another use of TemplateFields arises in scenarios when the underlying data needs to be displayed differently in the web page report than in the format it's stored in the database.
Imagine that the Employees table had a Gender field that stored the character M or F to indicate the sex of the employee. When displaying this information in a web page we might want to show the gender as either "Male" or "Female", as opposed to just "M" or "F". Both of these scenarios can be handled by creating a formatting method in the ASP.
NET page's code-behind class or in a separate class library, implemented as a static method that is invoked from the template.
Such a formatting method is invoked from the template using the same databinding syntax seen earlier. The formatting method can take in any number of parameters, but must return a string.
This returned string is the HTML that is injected into the template. To illustrate this concept, let's augment our tutorial to show a column that lists the total number of days an employee has been on the job. This formatting method will take in a Northwind. EmployeesRow object and return the number of days the employee has been employed as a string. This method can be added to the ASP. NET page's code-behind class, but must be marked as protected or public in order to be accessible from the template.
To utilize this method we need to invoke it from a TemplateField in the GridView using the databinding syntax. Its Row property returns the strongly-typed Northwind. This databinding syntax can appear directly in the ItemTemplate as shown in the declarative syntax below or can be assigned to the Text property of a Label Web control.
However, the Eval method returns an object , so we'd have to change our DisplayDaysOnJob method signature to accept an input parameter of type object , instead. Therefore, we'd need to accept an object as the input parameter for the DisplayDaysOnJob method, check to see if it had a database NULL value which can be accomplished using Convert.
Due to these subtleties, I've opted to pass in the entire EmployeesRow instance. In the next tutorial we'll see a more fitting example for using the Eval "columnName" syntax for passing an input parameter into a formatting method. The TemplateField in the GridView control allows for a higher degree of flexibility in displaying data than is available with the other field controls.
TemplateFields are ideal for situations where:. In addition to customizing the display of data, TemplateFields are also used for customizing the user interfaces used for editing and inserting data, as we'll see in future tutorials.
In Microsoft Word, you open, preview, or print your document. When you do this, some fields may not be updated while other fields are always updated. This issue occurs because certain fields are "display" fields. This means that they do not perform a calculation. These fields show a result even when you do not update them, and they appear whether you print the document.
Certain other fields are related to pagination and printing and are only updated when you print or preview your document. To resolve this issue, make sure that all fields are updated when you print or preview your document. To do this, follow these steps, as appropriate for the version of Word that you are running. Click to select the Update fields before printing check box, and then click OK. Fields are used as placeholders for data that might change in a document and for creating form letters and labels in mail-merge documents.
Some of the most common fields are the PAGE field, which is inserted when you add page numbers, and the DATE field, which is inserted when you click Date and Time on the Insert menu and then select the Update automatically check box. Fields are inserted automatically when you create an index or table of contents by using the Index and Tables command on the Insert menu.
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