com.smartgwt.client.docs.serverds

Class Validator

java.lang.Object

com.smartgwt.client.docs.serverds.Validator

public class Validator
extends java.lang.Object

A validator describes a check that should be performed on a value the user is trying to save.

This class is not meant to be created and used, it is actually documentation of settings allowed in a DataSource descriptor (.ds.xml file), for use with Smart GWT Pro Edition and above. See com.smartgwt.client.docs.serverds for how to use this documentation.

Validators are specified for DataSource fields via the DataSourceField.validators property. Validators that need not be run on the server can also be specified for a specific FormItem or ListGridField.

Smart GWT supports a powerful library of ValidatorTypes which have identical behavior on both the client and the server.

Beyond this, custom validators can be defined on the client and custom validation logic added on the server. Note that the regexp and mask validator types are very flexible and can be used to perform virtually any kind of formatting check that doesn't involve some large external dataset.

Custom validators can be reused on the client by adding them to the global validator list, via the addValidator() method.

See Also:

ValidatorType

Field Summary

Fields

Modifier and Type	Field and Description
AdvancedCriteria	applyWhen Used to create a conditional validator based on criteria.
boolean	caseSensitive Applies only to the "isUnique" validator and controls whether the search for existing records is case sensitive or not.
java.lang.Boolean	clientOnly Indicates this validator runs on the client only.
StringMethod	condition For a validator that is not a built-in ValidatorType, a Callback, function, or JavaScript expression to evaluate to see if this validator passes or fails.
java.lang.String[]	dependentFields User-defined list of fields on which this validator depends.
java.lang.String	errorMessage Text to display if the value does not pass this validation check.
java.lang.String	operationId Applies only to the "isUnique" validator; allows you to name a specific operation for the uniqueness check.
java.lang.String	serverCondition For validators of type "serverCustom" only: a scriptlet in any supported JSR223 scripting language which is run in order to see if validation passes.
ServerObject	serverObject For validators of type "serverCustom" only, a ServerObject declaration that allows the Smart GWT Server to find a Java class via a variety of possible approaches, and call a method on it to perform validation.
java.lang.Boolean	serverOnly Indicates this validator runs on the server only.
java.lang.Boolean	stopIfFalse Normally, all validators defined for a field will be run even if one of the validators has already failed.
java.lang.Boolean	stopOnError Indicates that if this validator is not passed, the user should not be allowed to exit the field - focus will be forced back into the field until the error is corrected.
ValidatorType	type Type of the validator.
java.lang.Boolean	validateOnChange If true, validator will be validated when each item's "change" handler is fired as well as when the entire form is submitted or validated.

Constructor Summary

Constructors

Constructor and Description
Validator()

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

caseSensitive

public boolean caseSensitive

Applies only to the "isUnique" validator and controls whether the search for existing records is case sensitive or not.

Default value is false

serverObject

public ServerObject serverObject

For validators of type "serverCustom" only, a ServerObject declaration that allows the Smart GWT Server to find a Java class via a variety of possible approaches, and call a method on it to perform validation.

The target object must implement a method whose first 4 arguments are: Object value, Validator validator, String fieldName, Map record

(com.isomorphic.datasource.Validator is a subclass of Map that represents a validator's configuration, and also provides APIs for implementing templated error messages).

You provide the name of the method to call by specifying methodName as part of the serverObject declaration. If you do not specify a methodName, Smart GWT expects to find a compliant method called "condition".

Additional arguments may be declared and are automatically supplied based on the declared argument type, via DMI. Available objects include:

• DataSource - the DataSource where this validator is declared, an instance of com.isomorphic.datasource.DataSource or a subclass
• HttpServletRequest - from standard Java servlets API
• HttpServletResponse - from standard Java servlets API
• ServletContext - from standard Java servlets API
• HttpSession - from standard Java servlets API
• RequestContext - an instance of com.isomorphic.servlet.RequestContext
• RPCManager - the RPCManager associated with the transaction this validation is part of; an instance of com.isomorphic.rpc.RPCManager
• DSRequest - the DSRequest this validation is part of; an instance of com.isomorphic.datasource.DSRequest
• DSField - the datasource field which value is validated; an instance of com.isomorphic.datasource.DSField
• ValidationContext - the context where value is validated; an instance of com.isomorphic.datasource.ValidationContext

Note that any servlet-related objects will not be available if your validator is run outside of the scope of an HTTP servlet request, such as a command-line process.

Note that "record" will contain only other values submitted at the same time, not the complete DataSource record. For most types of cross-field validation, you should fetch the current saved record. For example:

      final Map existingRecord = dataSource.fetchById(record);
  

Default value is null

operationId

public java.lang.String operationId

Applies only to the "isUnique" validator; allows you to name a specific operation for the uniqueness check.

Default value is null

errorMessage

public java.lang.String errorMessage

Text to display if the value does not pass this validation check.

If unspecified, default error messages exist for all built-in validators, and a generic message will be used for a custom validator that is not passed.

Default value is null

validateOnChange

public java.lang.Boolean validateOnChange

If true, validator will be validated when each item's "change" handler is fired as well as when the entire form is submitted or validated. If false, this validator will not fire on the item's "change" handler.

Note that this property can also be set at the form/grid or field level; If true at any level and not explicitly false on the validator, the validator will be fired on change - displaying errors and rejecting the change on validation failure.

Default value is null

dependentFields

public java.lang.String[] dependentFields

User-defined list of fields on which this validator depends. Primarily used for validators of type "custom" but can also be used to supplement applyWhen criteria.

Note that for validators run on the server, fields required due to dependentFields but not present in the DSRequest.data of an update because they haven't changed will be filled in from the server DataSource.

Default value is null

See Also:

applyWhen

stopOnError

public java.lang.Boolean stopOnError

Indicates that if this validator is not passed, the user should not be allowed to exit the field - focus will be forced back into the field until the error is corrected.

This property defaults to FormItem.stopOnError if unset.

Enabling this property also implies FormItem.validateOnExit is automatically enabled. If this is a server-based validator, setting this property also implies that FormItem.synchronousValidation is forced on.

Default value is null

applyWhen

public AdvancedCriteria applyWhen

Used to create a conditional validator based on criteria. The criteria defines when the validator applies. The form current values or ListGrid record is used as reference for the criteria. If the criteria match, then the validator will be processed. Otherwise the validator is skipped and assumed valid.

To use an applyWhen criteria the form or grid must use a DataSource.

NOTE: applyWhen is not supported for "binary" fields.

Server and client use

Conditional validators are enforced both on the server and on the client-side when defined on a DataSource field as shown in the examples below. Note the applyWhen element is treated as a Criterion.

  <!-- Normal format -->
  <field name="age" type="integer">
    <validators>
      <validator type="integerRange" min="0" max="100">
        <applyWhen operator="or">
          <criteria>
            <criterion fieldName="restrictAge" operator="equals" value="true"/>
            <criterion fieldName="gender" operator="equals" value="female"/>
          </criteria> 
        </applyWhen>
      </validator>
    </validators>
  </field>
 
  <!-- Conditional requirement -->
  <field name="reason" type="text">
    <validators>
      <validator type="required">
        <applyWhen fieldName="willAttend" operator="equals" value="false"/>
      </validator>
    </validators>
  </field>
  

The last example above shows an alternate to the requiredIf validator using a shorthand format which is only available for client-side use. On the client the reason field will change appearance to match other required or non-required fields when willAttend changes. Note that using applyWhen for a validator of type required as in the example may result in validation request being set to the server where a fetch is made against the DataSource. For more details, see the discussion at the end of the DataSourceField.required help topic.

Component XML and client-only use

Conditional validators can also be applied to Component XML similarly to provide client-only validations or read-only state management. A common use case is conditionally displaying or enabling fields. Use the readOnly validator with an applyWhen value to control the read-only appearance of a field. The example below shows a field which is hidden when willAttend=true.

  <!-- field definition within a Component XML DynamicForm -->
  <field name="reason" type="text">
    <validators>
      <validator type="readOnly" fieldAppearance="hidden">
        <applyWhen fieldName="willAttend" operator="equals" value="true"/>
      </validator>
    </validators>
  </field>
  

Conditional validators can be applied to DynamicForm or ListGrid fields in Java code as well.

Default value is null

serverCondition

public java.lang.String serverCondition

For validators of type "serverCustom" only: a scriptlet in any supported JSR223 scripting language which is run in order to see if validation passes. For example:

      <validator type="serverCustom">
          <serverCondition language="groovy"><![CDATA[
              value < dataSources.StockItem.fetchById(record.itemId).quantity
          ]]></serverCondition>
      </validator>
  

The scriptlet should return a boolean true or false value - failing to return a value will be considered a false result (validator failed). If your expression is syntactically invalid, an exception is thrown and the error message is displayed in the client.

See ServerScript for general information on Server Scripting and JSR223, and VelocitySupport for general information on Velocity support, and also see below for special rules for Velocity.

Available variables The following variables are available in a serverCondition:

• dataSource - The current DataSource
• record - Other submitted values part of the same update
• value - The value of the field
• validator - The config of this validator, including all attributes declared on the <validator> tag, presented as a Map
• field - The field (as a DSField object)

Note that "record" will contain only other values submitted at the same time, not the complete DataSource record. For most types of cross-field validation, you should fetch the current saved record using the server-side API DataSource.fetchById(). For example, in Velocity:

      $dataSource.fetchById($record.primaryKeyField).otherFieldName
  

Note that, while a DSRequest provides dsRequest.oldValues, these values cannot be relied upon for a security check since they could be faked.

Server-side custom validators also have access to the standard set of context variables that come from the Servlet API. However, be aware that if you write conditions that depend upon these variables, you preclude your Validator from being used in the widest possible variety of circumstances; for example, in a command-line process. Rather, it will be tied to operating in the context of, say, an HttpSession.

Given the above caveat, the following context variables are also available:

• servletRequest - The associated HttpServletRequest
• session - The associated HttpSession
• httpParameters - This variable gives you access to the parameters Map of the associated HttpServletRequest; it is an alternate form of $servletRequest.getParameter
• requestAttributes - This variable gives you access to the attributes Map of the associated HttpServletRequest; it is an alternate form of $servletRequest.getAttribute
• sessionAttributes - This variable gives you access to the attributes Map of the associated HttpSession; it is an alternate form of $session.getAttribute

Special considerations for Velocity

To return a true or false value in Velocity, you script can either be just an expression that returns a boolean value, or the result of evaluating the Velocity template can result in output of "true" or "false". All of the following are valid forms:

$value < 100
$util.contains($value, "some string")
$record.someField(assuming that "someField" contains a boolean value)
$value > $record.otherField

For additional troubleshooting information when Velocity expressions aren't working as expected, set the log category org.apache.Velocity to DEBUG in log4j.isc.config.xml.

Because it's tricky to call arbitrary Java methods in Velocity, the following special objects are passed to Velocity for convenience:

• dataSources - The list of all DataSources, accessible by name (so, for example, $dataSources.supplyItem refers to the supplyItem DataSource object).
• util - A com.isomorphic.util.DataTools object, giving you access to all of that class's useful helper functions

Default value is null

stopIfFalse

public java.lang.Boolean stopIfFalse

Normally, all validators defined for a field will be run even if one of the validators has already failed. However, if stopIfFalse is set, validation will not proceed beyond this validator if the check fails.

This is useful to prevent expensive validators from being run unnecessarily, or to allow custom validators that don't need to be robust about handling every conceivable type of value.

Default value is false

type

public ValidatorType type

Type of the validator.

This can be one of the built-in ValidatorType, the string "custom" to define a custom validator, or the string "serverCustom" to define a server-only custom validator.

Default value is null

serverOnly

public java.lang.Boolean serverOnly

Indicates this validator runs on the server only.

Default value is null

clientOnly

public java.lang.Boolean clientOnly

Indicates this validator runs on the client only.

Normally, if the server is trying to run validators and finds a validator that it can't execute, for safety reasons validation is considered to have failed. Use this flag to explicitly mark a validator that only needs to run on the client.

Default value is false

condition

public StringMethod condition

For a validator that is not a built-in ValidatorType, a Callback, function, or JavaScript expression to evaluate to see if this validator passes or fails.

Because the validator declaration itself is passed as a parameter to condition(), you can effectively parameterize the validator. For example, to create a validator that checks that the value is after a certain date:

 
      { type:"custom", afterDate:new Date(), 
        condition:"value.getTime() > validator.afterDate.getTime()" }
  

Reusable validators, like the above, can be registered as a standard validatorType by calling addValidator().

Note that, if a field is declared with a builtin FieldType, the value passed in will already have been converted to the specified type, if possible.

For the required parameters, see the documentation for ValidatorConditionCallback.

Default value is null

Constructor Detail

Validator

public Validator()