Lookup In Select of URL For Power Pages

 While working on a Power Pages implementation I was consume the Power Pages API to get a Lookup table so I could show and hide information on the form using jQuery.  One issue I was having is I couldn't get a lookup field to return even though I had it as a field in the site setting for the table and included it in the my select statement in the URL.  I kept getting an `unexpected error occurred`.

This issue is caused because lookup's are made up using 3 fields.

1) Formatted Value = The information you see in the lookup field (i.e. the record name)

2) Logical Name = The table the related record is a part of

3) Id = The id of the related record

In the api there is a 4th field that is returned that is the Associated Navigation Property and it is the logical name of the lookup field.

When setting up our select and even saying what columns can be returned in the API, we have to think how the OData endpoint will return the data to us.  The easy way to do this with a lookup is to add a `_` to the beginning of the field schema name and append `_value` to the end of the schema name.

Example:

`_new_lookupField_value`

Place that value in the fields site setting for the enabled endpoint, if not using `*` and add it to your select statement in the URL.  You should see the error go away and you should see returned data similar to this

 {  
      "@odata.context": "https://myportal.powerappsportals.com/_api/$metadata#new_example(new_name,_new_lookupField_value)",  
      "@Microsoft.Dynamics.CRM.totalrecordcount": -1,  
      "@Microsoft.Dynamics.CRM.totalrecordcountlimitexceeded": false,  
      "@Microsoft.Dynamics.CRM.globalmetadataversion": "3068318",  
      "value": [  
           {  
                "@odata.etag": "W/\"3066510\"",  
                "new_name": "Example Name",  
                "_new_lookupField_value@OData.Community.Display.V1.FormattedValue": "Example Lookup",  
                "_new_lookupField_value@Microsoft.Dynamics.CRM.associatednavigationproperty": "new_LookupField",  
                "_new_lookupField_value@Microsoft.Dynamics.CRM.lookuplogicalname": "new_relatedTable",  
                "_new_lookupField_value": "2a9c7024-7ca0-4707-f086-419f27c27541"  
           },{  
                "@odata.etag": "W/\"2610804\"",  
                "new_name": "Example of Null",  
                "_new_lookupField_value": null  
           }  
      ]  
 }  

In the above JSON there are two records returned.  One where the lookup contains data and one where it is empty.