Criteria for selecting only a matching set of records from a DataSource. Criteria can be applied on the client and server. Unless configured otherwise, criteria will generally be applied client-side by ResultSets via ResultSet.applyFilter().

Client- and server-side systems built into SmartClient understand two criteria formats by default: simple key-value pairs (Criteria) or the AdvancedCriteria format.

Simple key-value Criteria are represented via a JavaScript Object where each property specifies the name and required value for a field. Multiple legal values for a field can be provided as an Array. For example:

 var criteria = {     field1 : "value1",     field2 : ["value2", "value3"]  }  

AdvancedCriteria is a format for representing search criteria which may include operators on field values such as "less than", or may include sub-clauses such as several criteria applied to fields joined by an "OR" operator.

SmartClient DataSources can use AdvancedCriteria to search a list of Records, and the SmartClient Java Server can translate AdvancedCriteria to either SQL or Hibernate queries (Note: The server-side AdvancedCriteria handling feature is only available with the Power and Enterprise Editions of SmartClient; the Pro Edition is limited to ordinary criteria handling on the server side).可惜Power版和Enterprise版都老贵老贵的，企业版的都有按CPU卖的了，晕倒。

If the entire dataset is cached locally, SmartClient can perform AdvancedCriteria filtering on the client, avoiding a server call.

An AdvancedCriteria is an ordinary JavaScript object which can be created directly with JavaScript literal notation. For example:

var advancedCriteria = {
        _constructor:"AdvancedCriteria",
        operator:"and",
        criteria:[
            // this is a Criterion
            { fieldName:"salary", operator:"lessThan", value:"80000" },
            { operator:"or", criteria:[
                  { fieldName:"title", operator:"iContains", value:"Manager" },
                  { fieldName:"reports", operator:"notNull" }
              ]  
            }
        ]
    }