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Hi,

I have a database with two collections. On my app page, I have one "select" control, and I use it to list classnames from my classes collection. Now, after I choose one, I want to list all students with the same classname(I already did the pointer thing in the database) in a "list" control right below the "select" control. How will I tell the service which item is selected in the "select" control?

Hello,

Please follow these steps:

1. add "list/query" service datasource on the page.

2. open "before send" mapping.

3. find "where" request parameter and click "JS" on this parameter.

4. populate it with following JS code:

   pre

   //Note you need to replace "selectName" with your select component name.
   var classValue = Apperyio("selectName").val();

   //Where "class" is your pointer field.
   var whereObject = {"class": {"$inQuery": {_id: classValue } } };

   return JSON.stringify(whereObject);

   /pre

   Regards.

is there a video or tutorial about this? I find it difficult to do that.

Hi,

1. Here are docs about List and Query services settings http://devcenter.appery.io/documentat...
   http://devcenter.appery.io/documentat...
2. Mapping http://devcenter.appery.io/documentat...