SmartFunctions

SmartFunctions are the engine for setting permissions in Fluree. This section details the role of smart functions.

To see a full list of all accepted smart functions, see smart function list.

We also have a Github repo with basic smart functions you can add to your applications.

For some additional help testing and debugging your smart function implementations, try updating your logback.xml configuration file (located in your Fluree directory) so that logging for fluree.db is set to DEBUG, e.g.

<configuration scan="true">
    ...
    <logger name="fluree.db" level="DEBUG"/>
    ...
</configuration>

In this setting, Fluree will log the entirety of the Smart Function Stack, so that every time a query/transaction triggers the evaluation of a smart function, you can observe its invocation, context, and result.

Role of Smart Functions

Every time a transaction is issued, that transaction might trigger various smart functions. In addition, when an end user issues a query, various smart functions might be triggered.

Smart functions will either return true or false. If every smart function that is triggered returns a true, then the transaction will go through. If even one triggered smart function returns false, then the transaction will fail, or in the case of a query- that piece of information will not be displayed to the user.

Smart functions are stored in the _fn collection. From the _fn collection, smart functions can be referenced in a variety of places. Functions stored in different locations are triggered in slightly different ways.

Location	When Trigged?
_rule/fns	When an _auth record containing a given _rule issues a query or transaction containing the _collection or _predicates specified in the rule.
_collection/spec	When transaction containing the specified _collection is issued, regardless of the issuer.
_predicate/spec	When transaction containing the specified _predicate is issued, regardless of issuer (once per specified predicate).
_predicate/txSpec	When transaction containing the specified _predicate is issued, regardless of who issuer (once per transaction).
In transactions	You can use smart functions directly in transactions, but their role and behavior is slightly different.