Store Formula in String Field and Convert to Datetime?

Question

I am working on building a rules processor and have a text (string) field in a custom metadata type that I would like to store a formula in (i.e. datetime.now()) and then convert to the correct field format within apex. Is this something that can be done? I know that I can use something like below to parse an actual datetime string:

(field.ValueType__c == 'Date/Time'){
DateTime dt = DateTime.parse(field.ValueType__c);    
o.put(field.APIFieldName__c, dt); 

In the custom metadata I am storing Value, ValueType, and IsFormula, but am having trouble figuring out how to actually set the formula for the datetime variable. Thanks.

Answer 1

There's no way to "evaluate apex" on-the-fly (at least, not in the traditional sense), but you can get some limited support for formulas via apex:outputText, or you can perform a callout to execute anonymous (requires administrative permissions). The caveat for using apex:outputText is that you must be in a Visualforce context.

Here's an example that should work in a Visualforce context:

Component.Apex.OutputText c = new Component.Apex.OutputText();
c.expressions.value = '{!NOW()}';
DateTime dt = DateTime.valueOf(c.value);

However, as stated, it will not work in other contexts, like triggers, batchable, etc.

For now, you might want to vote on this idea.