# Field Represents a value that is stored in a custom field. The custom fields themselves are represented by the [Fields](v1-Fields.html) class. Extends [BaseEntity](v1-BaseEntity.html). ## Properties | Name | Type | Description | | --- | --- | --- | | static dateTimeType | String | Read-only.  Date and time field type. Used when defining rule requirements. | | static dateType | String | Read-only.  Date field type. Used when defining rule requirements. | | static floatType | String | Read-only.  Float field type. Used when defining rule requirements. | | static integerType | String | Read-only.  Integer field type. Used when defining rule requirements. | | static periodType | String | Read-only.  Period field type. Used when defining rule requirements. | | static stringType | String | Read-only.  String field type. Used when defining rule requirements. | | static textType | String | Read-only.  Text field type. Used when defining rule requirements. | | backgroundColor | String | Read-only.  The background color of the value in the custom field as it is displayed in YouTrack. | | becomesRemoved | Boolean | Read-only.  When `true`, the entity is removed in the current transaction. Otherwise, `false`. This property can become `true` only in on-change rules when the rule is triggered on the removal of an issue or an article. In the rule code, the `runOn` rule property must contain the `removal` parameter set to `true`. Available since 2017.4.37915 ```JAVASCRIPT runOn: {removal: true} ``` | | colorIndex | Number | Read-only.  The index value of the color that is assigned to the value in the custom field. | | description | String | Read-only.  The description of the value as visible in the administrative UI for custom fields. | | extensionProperties | Object | The object containing extension properties for this entity and their values. Extension properties are custom properties that might be added to core YouTrack entities by an app. For details about extension properties, see [Extension Properties](apps-extension-properties.html). Available since 2024.3 ```JAVASCRIPT const entities = require('@jetbrains/youtrack-scripting-api/entities'); exports.rule = entities.Issue.action({ command: 'test', action: function (ctx) { const printValues = () => { return 'stringProp:' + ctx.issue.extensionProperties.stringProp + ';' + 'integerProp:' + ctx.issue.extensionProperties.integerProp + ';' + 'booleanProp:' + ctx.issue.extensionProperties.booleanProp + ';' + 'issueProp:' + ctx.issue.extensionProperties.issueProp?.id + ';' + 'issuesProp:' + ctx.issue.extensionProperties.issuesProp?.first()?.id + ';' } ctx.issue.addComment(printValues()); } }); ``` | | foregroundColor | String | Read-only.  The foreground color of the value in the custom field as it is displayed in YouTrack. | | isArchived | Boolean | Read-only.  If the value is archived, this property is `true`. | | isNew | Boolean | Read-only.  When `true`, the entity is created in the current transaction. Otherwise, `false`. Available since 2018.2.42351 | | name | String | Read-only.  The name of the value, which is also stored as the value in the custom field. | | ordinal | Number | Read-only.  The position of the value in the set of values for the custom field. | | presentation | String | Read-only.  String representation of the value. | ## Methods ### becomes ```JAVASCRIPT becomes(fieldName, expected) ``` Checks whether a field is set to an expected value in the current transaction. Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field to check. | : | expected | string | The expected value. | Return Value : | Type | Description | : | --- | --- | : | boolean | If the field is set to the expected value, returns `true`. | ### canBeReadBy ```JAVASCRIPT canBeReadBy(fieldName, user) ``` Checks whether a user has permission to read the field. Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field. | : | user | [User](v1-User.html) | The user for whom the permission to read the field is checked. | Return Value : | Type | Description | : | --- | --- | : | boolean | If the user can read the field, returns `true`. | ### canBeWrittenBy ```JAVASCRIPT canBeWrittenBy(fieldName, user) ``` Checks whether a user has permission to update the field. Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field. | : | user | [User](v1-User.html) | The user for whom the permission to update the field is checked. | Return Value : | Type | Description | : | --- | --- | : | boolean | If the user can update the field, returns `true`. | ### is ```JAVASCRIPT is(fieldName, expected) ``` Checks whether a field is equal to an expected value. Available since 2019.2.55603 Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field to check. | : | expected | string | The expected value. | Return Value : | Type | Description | : | --- | --- | : | boolean | If the field is equal to the expected value, returns `true`. | ### isChanged ```JAVASCRIPT isChanged(fieldName) ``` Checks whether the value of a field is changed in the current transaction. Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field to check. | Return Value : | Type | Description | : | --- | --- | : | boolean | If the value of the field is changed in the current transaction, returns `true`. | ### oldValue ```JAVASCRIPT oldValue(fieldName) ``` Returns the previous value of a single-value field before an update was applied. If the field is not changed in the transaction, returns `null`. Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field. | Return Value : | Type | Description | : | --- | --- | : | Object | If the field is changed in the current transaction, the previous value of the field. Otherwise, `null`. | ### required ```JAVASCRIPT required(fieldName, message) ``` Asserts that a value is set for a field. If a value for the required field is not set, the specified message is displayed in the user interface. Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field to check. | : | message | string | The message that is displayed to the user that describes the field requirement. | ### was ```JAVASCRIPT was(fieldName, expected) ``` Checks whether a field was equal to an expected value prior to the current transaction. Available since 2019.2.55603 Parameters : | Name | Type | Description | : | --- | --- | --- | : | fieldName | string | The name of the field to check. | : | expected | string | The expected value. | Return Value : | Type | Description | : | --- | --- | : | boolean | If the field was equal to the expected value, returns `true`. | ## See also [BaseEntity](v1-BaseEntity.html) [Extension Properties](apps-extension-properties.html) [User](v1-User.html)