# Fields

Fields are a convenient way to show non-static data in the document. In this way, you could present different data to the end-user without actually changing the document content.

This topic contains the following sections:

* [Field Types](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/fields-and-document-variables/fields#field-types)

* [Display Modes](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/fields-and-document-variables/fields#display-modes)

* [Inserting a Field](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/fields-and-document-variables/fields#inserting-a-field)

* [Fields Update Priority](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/fields-and-document-variables/fields#fields-update-priority)

## Field Types

In **RadDocument** the base class for all fields is **CodeBasedField**. It is an abstract class that can be inherited from. Some of the implemented and ready-to-use field types are:

* **DateField**: Inserts the current date in one of the specified formats.

* **PageField**: Shows the current page number.

* **NumPagesField**: Shows the number of pages in the document.

* **MergeField**: Used in mail-merge scenarios. You can read more here: [Mail Merge](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/mail-merge/mail-merge).

* **IncludePictureField**: Specifies the URI from which an image must be retrieved.

* **DocumentVariableField**: А field which uses **DocumentVariables**. More information can be found here: [Document Variables](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/fields-and-document-variables/document-variables).

* **SequentialField**: Tracks the number of tables and figures inserted in the document before a place in the document,so that the **InsertCaption()** method would use the correct number. Find more here: [Captions for tables and Figures](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/references/captions-for-tables-and-figures).

* **StyleReferenceField**: The type of field that a reference field refers to when a cross-reference to a Heading style is inserted.

* **ReferenceField**: Used to refer to a bookmark or other type of field. It is inserted when a cross-reference to a table or figure caption is added to the document. Find more here: [Cross Reference](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/references/cross-reference).

* **PageReferenceField**: Used in table of contents in order to be able to navigate to the respective page on Ctrl + Click.

* **HyperlinkField**: Inserted in hyperlinks to store information about the navigation URI.

* **TCField**: Used in table of contents to describe one entry. They include the text of the entry and the page reference field.

* **AuthorField**: The type of field is related to track changes, specifies the name of the user that has modified the document part. Read more here: [Track Changes](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/track-changes).

* **CitationField**: Inserted when you add a citation to the document.

* **BibliographyField**: Inserted in the document when you want to add information about the bibliographic sources used in the document. Read more here: [Bibliographic References](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/references/bibliographic-references).

## Display Modes

Fields normally have two modes – *Code* and *Result*. When in code mode, they appear as `{<FieldTypeName> [<field parameter>] [<switch> <switch parameter>]*}`.

For instance, Page Fields appear as `{ PAGE }`, Merge Fields as `{ MERGEFIELD FirstName }`
or `{ MERGEFIELD FirstName \b "text that will appear before the merge field if it is not empty" }`.

In result mode, all fields get evaluated depending on some conditions – the place in the document where they appear in the case of page fields, the current mail merge record for merge fields, etc.

**MergeFields** have one additional mode – *DisplayName* that shows the property path they use in brackets of the type `<<[PropertyPathHere]>>`. Furthermore, there are specific methods and commands of the editor that change the display mode of merge fields or even remove them from the document altogether, replacing them with the **ResultFragment**. More information on this topic can be found in the [Mail Merge](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/mail-merge/mail-merge) article.

## Inserting a Field

Inserting any type of field in the document of an editor can be done with the **InsertField()** method.

#### Insert a page field:

```C#
this.radRichTextEditor1.InsertField(new PageField());
```

```VB.NET
Me.radRichTextEditor1.InsertField(New PageField())
```

Update of a field can be triggered from the context menu or using the **UpdateField()** method of **RadRichTextEditor** by passing the **FieldRangeStart** of the field as a parameter.

#### Update a field:

```C#
this.radRichTextEditor1.UpdateField(new FieldRangeStart());
```

```VB.NET
Me.radRichTextEditor1.UpdateField(New FieldRangeStart())
```

You can also update all fields in the current document with the **UpdateAllFields()** method of **RadRichTextEditor**.

## Fields Update Priority

All field types in the context of **RadDocument** have an update priority which determines when they should be updated when the **UpdateAllFields()** method is invoked. Most fields have the default value *0*. Changing it is needed in case a field depends on the evaluated value of another field to be properly evaluated.

Priority can be specified through the **FieldsUpdateManager** static class. The following code snippet shows how to set higher priority for a specific field type, causing all fields of this type to be updated before the rest of the fields when calling **UpdateAllField()**:

```C#
FieldsUpdateManager.RegisterFieldUpdateInfo(typeof(ReferenceField), new FieldTypeUpdateInfo() { Priority = 1000 });
```

```VB.NET
FieldsUpdateManager.RegisterFieldUpdateInfo(GetType(ReferenceField), New FieldTypeUpdateInfo() With {.Priority = 1000})
```

> warning Having many different values for field priory is not recommended and may lead to performance degradation of the **UpdateAllFields()** method. The reason for this is that all fields with the same priority are updated in a batch update. Having more priority groups leads to execution of more batch updates.

## See Also

* [Custom Fields](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/fields-and-document-variables/custom-fields)

* [Mail Merge](https://www.telerik.com/products/winforms/documentation/controls/richtexteditor/features/mail-merge/mail-merge)