Package org.kuali.rice.krad.uif.view

Class DefaultExpressionEvaluator

java.lang.Object
org.kuali.rice.krad.uif.view.DefaultExpressionEvaluator
All Implemented Interfaces:
ExpressionEvaluator
public class DefaultExpressionEvaluator extends Object implements ExpressionEvaluator
Evaluates expression language statements using the Spring EL engine
Author:
Kuali Rice Team (rice.collab@kuali.org)

  • Field Details

    • SERVER_EVALUATION_PATTERN

      protected static final Pattern SERVER_EVALUATION_PATTERN

    • parser

      protected static org.springframework.expression.ExpressionParser parser

  • Constructor Details

    • DefaultExpressionEvaluator

      public DefaultExpressionEvaluator()
      Default constructor

  • Method Details

    • populatePropertyExpressionsFromGraph

      public void populatePropertyExpressionsFromGraph(UifDictionaryBean expressionConfigurable, boolean buildRefreshGraphs)
      Pulls expressions within the expressionConfigurable's expression graph and moves them to the property expressions map for the expressionConfigurable or a nested expressionConfigurable (for the case of nested expression property names)

      Expressions that are configured on properties and pulled out by the

      invalid reference 
      org.kuali.rice.krad.uif.util.UifBeanFactoryPostProcessor
      and put in the UifDictionaryBean.getExpressionGraph() for the bean that is at root (non nested) level. Before evaluating the expressions, they need to be moved to the UifDictionaryBean.getPropertyExpressions() map for the expressionConfigurable that property is on.

      Specified by:
      populatePropertyExpressionsFromGraph in interface ExpressionEvaluator
      Parameters:
      expressionConfigurable - expressionConfigurable instance to process expressions for
      buildRefreshGraphs - indicates whether the expression graphs for component refresh should be built

    • parseExpression

      public String parseExpression(String exp, List<String> controlNames, Map<String,Object> context)
      Takes in an expression and a list to be filled in with names(property names) of controls found in the expression.

      This method returns a js expression which can be executed on the client to determine if the original exp was satisfied before interacting with the server - ie, this js expression is equivalent to the one passed in.

      There are limitations on the Spring expression language that can be used as this method. It is only used to parse expressions which are valid case statements for determining if some action/processing should be performed. ONLY Properties, comparison operators, booleans, strings, matches expression, and boolean logic are supported. Server constants and calls will be evaluated early. The isValueEmpty, listContains, and emptyList custom KRAD functions, however, will be converted to a js equivalent function. Properties must be a valid property on the form, and should have a visible control within the view.

      Example valid exp: "account.name == 'Account Name'"

      Specified by:
      parseExpression in interface ExpressionEvaluator
      Parameters:
      exp - the expression to convert to a js condition
      controlNames - the list to populate with control names found in the expression (these may later be used to add js change handlers)
      Returns:
      the converted expression into an equivalent js condition

    • findControlNamesInExpression

      public List<String> findControlNamesInExpression(String exp)
      Find the control names (ie, propertyNames) used in the passed in expression
      Specified by:
      findControlNamesInExpression in interface ExpressionEvaluator
      Parameters:
      exp - the expression to search
      Returns:
      the list of control names found (ie, propertyNames)

    • evaluateCurrentStack

      protected void evaluateCurrentStack(String stack, List<String> controlNames)
      Used internally by parseExpression to evaluate if the current stack is a property name (ie, will be a control on the form)

    • initializeEvaluationContext

      public void initializeEvaluationContext(Object contextObject)
      Initializes the expression context for the given expression context object

      The object given here will form the default context for expression terms (terms without any variable prefix)

      Specified by:
      initializeEvaluationContext in interface ExpressionEvaluator
      Parameters:
      contextObject - instance of an Object

    • evaluateExpressionsOnConfigurable

      public void evaluateExpressionsOnConfigurable(View view, UifDictionaryBean expressionConfigurable, Map<String,Object> evaluationParameters)
      Evaluates any el expressions that are found as a string property value for the object

      Using reflection the properties for the object are retrieved and if of String type the corresponding value is retrieved. If the value is not empty and contains the el placeholder see ExpressionEvaluator.containsElPlaceholder(String) then the expression is evaluated using the given context object and parameters. The evaluated string is then set as the new property value, or in the case of a template (expression contained within a literal string), the expression part is replaced in the property value.

      In addition to evaluating any property expressions, any configured PropertyReplacer for the object are also evaluated and if a match occurs those property replacements are made

      Specified by:
      evaluateExpressionsOnConfigurable in interface ExpressionEvaluator
      Parameters:
      view - view instance being rendered
      expressionConfigurable - object whose properties should be checked for expressions and evaluated
      evaluationParameters - map of parameters that may appear in expressions, the map key gives the parameter name that may appear in the expression, and the map value is the object that expression should evaluate against when that name is found

    • evaluateExpression

      public Object evaluateExpression(Map<String,Object> evaluationParameters, String expressionStr)
      Evaluates the given el expression against the content object and parameters, and returns the result of the evaluation

      The given expression string is assumed to be one el expression and should not contain the el placeholders. The returned result depends on the evaluation and what type is returns, for instance a boolean will be return for a boolean expression, or a string for string expression

      Specified by:
      evaluateExpression in interface ExpressionEvaluator
      Parameters:
      evaluationParameters - map of parameters that may appear in expressions, the map key gives the parameter name that may appear in the expression, and the map value is the object that expression should evaluate against when that name is found
      expressionStr - el expression to evaluate
      Returns:
      Object result of the expression evaluation

    • evaluateExpressionTemplate

      public String evaluateExpressionTemplate(Map<String,Object> evaluationParameters, String expressionTemplate)
      Evaluates the given expression template string against the context object and map of parameters

      If the template string contains one or more el placeholders (see ExpressionEvaluator.containsElPlaceholder(String)), the expression contained within the placeholder will be evaluated and the corresponding value will be substituted back into the property value where the placeholder occurred. If no placeholders are found, the string will be returned unchanged

      Specified by:
      evaluateExpressionTemplate in interface ExpressionEvaluator
      Parameters:
      evaluationParameters - map of parameters that may appear in expressions, the map key gives the parameter name that may appear in the expression, and the map value is the object that expression should evaluate against when that name is found
      expressionTemplate - string that should be evaluated for el expressions
      Returns:
      String formed by replacing any el expressions in the original expression template with their corresponding evaluation results

    • evaluatePropertyExpression

      public void evaluatePropertyExpression(View view, Map<String,Object> evaluationParameters, UifDictionaryBean expressionConfigurable, String propertyName, boolean removeExpression)
      Evaluates the configured expression for the given property name (if not exists) on the given configurable
      Specified by:
      evaluatePropertyExpression in interface ExpressionEvaluator
      Parameters:
      view - view instance the configurable is associated with, used to adjust binding prefixes
      evaluationParameters - map that will be exposed as EL parameters
      expressionConfigurable - configurable object to pull and evaluate the expression on
      propertyName - name of the property whose expression should be evaluated
      removeExpression - boolean that indicates whether the expression should be removed after evaluation

    • containsElPlaceholder

      public boolean containsElPlaceholder(String value)
      Indicates whether or not the given string contains the el placeholder (begin and end delimiters)
      Specified by:
      containsElPlaceholder in interface ExpressionEvaluator
      Parameters:
      value - String to check for contained placeholders
      Returns:
      boolean true if the string contains one or more placeholders, false if it contains none
      See Also:

    • replaceBindingPrefixes

      public String replaceBindingPrefixes(View view, Object object, String expression)
      Adjusts the property expressions for a given object

      The UifConstants.NO_BIND_ADJUST_PREFIX prefix will be removed as this is a placeholder indicating that the property is directly on the form. The UifConstants.FIELD_PATH_BIND_ADJUST_PREFIX prefix will be replaced by the object's field path - this is only applicable to DataFields. The UifConstants.DEFAULT_PATH_BIND_ADJUST_PREFIX prefix will be replaced by the view's default path if it is set.

      Specified by:
      replaceBindingPrefixes in interface ExpressionEvaluator
      Parameters:
      view - the parent view of the object
      object - Object to adjust property expressions on
      expression - The expression to adjust
      Returns:
      the adjusted expression String

    • retrieveCachedExpression

      protected org.springframework.expression.Expression retrieveCachedExpression(String expressionTemplate)
      Attempts to retrieve the Expression instance for the given expression template, if not found one is created and added to the cache
      Parameters:
      expressionTemplate - template string for the expression
      Returns:
      Expression instance

    • addCustomFunctions

      protected void addCustomFunctions(org.springframework.expression.spel.support.StandardEvaluationContext context)
      Registers custom functions for el expressions with the given context
      Parameters:
      context - - context instance to register functions to

    • evaluatePropertyReplacers

      protected void evaluatePropertyReplacers(View view, UifDictionaryBean expressionConfigurable, Map<String,Object> evaluationParameters)
      Iterates through any configured PropertyReplacer instances for the component and evaluates the given condition. If the condition is met, the replacement value is set on the corresponding property
      Parameters:
      view - - view instance being rendered
      expressionConfigurable - - expressionConfigurable instance with property replacers list, should be either a component or layout manager
      evaluationParameters - - parameters for el evaluation

    • evaluatePropertyExpressions

      protected void evaluatePropertyExpressions(View view, UifDictionaryBean expressionConfigurable, Map<String,Object> evaluationParameters)
      Iterates through the keys of the property expressions map and invokes evaluatePropertyExpression(org.kuali.rice.krad.uif.view.View, java.util.Map, org.kuali.rice.krad.datadictionary.uif.UifDictionaryBean, String, boolean)

      If the expression is an el template (part static text and part expression), only the expression part will be replaced with the result. More than one expressions may be contained within the template

      Parameters:
      view - - view instance that is being rendered
      expressionConfigurable - - object instance to evaluate expressions for
      evaluationParameters - - map of additional parameters that may be used within the expressions

    • getLinePathPrefixValue

      protected static String getLinePathPrefixValue(Component component)
      Determines the value for the UifConstants.LINE_PATH_BIND_ADJUST_PREFIX binding prefix based on collection group found in the component context
      Parameters:
      component - - component instance for which the prefix is configured on
      Returns:
      String line binding path or empty string if path not found