WSO2 DSS解析mongoDB查询结果

Question

I try to connect to mongoDB using WSO2 DSS and its mongoDB data source and present the result via a service. When setting the output mapping for a simple query result I cannot access the individual objects attributes. The only way to access the result is through a "virtual" column "document". For instance for a query like this:

<query id="mongo_find" useConfig="mongo_ds">
   <expression>things.find()</expression>
   <result outputType="json">
   {
      "entries": {
         "entry": [
             {
                "field1": $document
             }
         ]
      }
   }
   </result>
</query>

I get results like this:

<entry>
   <field1>
      { "_id" : { "$oid" : "54e489adb4ca0903f9675824"} , "x" : 3.0}
   </field1>
</entry>

However I would like to map the field1 directly to the "_id" attribute. Unfortunatelly I am unable to figure out how? The samples in documentation are not much help in this.

Answer 1

Try this:

<query id="mongo_find" useConfig="mongo_ds">
   <expression>things.find()</expression>
     <result outputType="json">
      {
       "entries": {
         "entry": [
            {
               "field1": $document._id
            }
         ]
       }
     }
    </result>
</query>