ERROR

Question

Getting this below mentioned query: 
 Could not display interface. Please check definition and inputs. Interface Definition: Expression evaluation error in rule 'isbn_mapbookdetails': Invalid index: Cannot index property 'body' of type Text into type Text 
 
 Since, I am new to Appian, is there anyone who can help me out?

Harshit Bumb (Appyzie) · Answer

You have used ".body" somewhere and this parameter is not present in the variable. Please use property() function to resolve as it allows you to pass a default value in case the parameter is not present.
If the error still persists, then I request you to add the code of 'isbn_mapbookdetails' rule.

Dave Lewis · Answer

Since you're trying to index something from mapbookdetails that ostensibly has a complex structure, and it says it's of type Text, that leads me to one conclusion. 
 Whatever you're doing to generate the list of mapbookdetails is returning no results. No results usually takes the form of {}, and Appian for whatever reason loves to implicitly cast {} as type Text. So your real questions to answer are: 
 Is it really generating no results? And if so... 
 Why is it generating no results? Also "Always, or sometimes?"