pentaho数据集成中的JSON输入

Question

我json数组json来自mongoDb。

"{ "_id" : { ""$oid"" : ""54b76bce44ae90e9e919d6e1""} ,
"_class" : ""com.argusoft.hkg.nosql.model.HkEventDocument"" , "featureName" : "EVENT" , 
"instanceId" : 577 , 
"fieldValue" : 
            { "reg_label_type" : "types" , 
              "third_custom_field" : "tttttttttttttttt" ,"people_capacity1": "20"} 
, "sectionList" : 
             [ { "sectionName" : "REGISTRATION" ,
                "customFields" : 
                               [ { "_id" : 577 , "fieldValue" :{ "multiselect1" : [ "[]"] , "datess" : { "$date" : "2015-01-16T18:30:00.000Z"}}}]} , { "sectionName" : "INVITATIONCARD" , "customFields" : [ ]}] , "franchiseId" : 2}"; 

我想访问fieldValue输入中的json数组。我怎么能这样做？