How do I add FunctionMappers to ExpressionManager in 7.18

Camunda 7 Topics Discussion & Questions
2

Hi @brepine ,

now you can only add functions via the ExpressionManager interface. If you want to keep using your custom function mappers, you could subclass the existing ExpressionManager, e. g. write a subclass of the JuelExpressionManager which only overwrites the createFunctionMapperFunction which then enables you to respect additional function mappers.

I could think of something like the following. Warning: I have not tested this code.

public class CustomJuelExpressionManager extends JuelExpressionManager {

    private Collection<FunctionMapper> additionalFunctionMappers = new LinkedList<>();

    public void addFunctionMapper(FunctionMapper functionMapper) {
        additionalFunctionMappers.add(functionMapper);
    }

    @Override
    protected FunctionMapper createFunctionMapper() {
        FunctionMapper baseMapper = super.createFunctionMapper();
        return new FunctionMapper() {
            @Override
            public Method resolveFunction(String prefix, String localName) {
                return Optional.ofNullable(baseMapper.resolveFunction(prefix, localName))
                        .or(() -> additionalFunctionMappers.stream().flatMap(mapper -> Optional.ofNullable(mapper.resolveFunction(prefix, localName)).stream()).findFirst())
                        .orElse(null);
            }
        };
    }
}

Otherwise, you would need to rewrite your function mappers and register every function itself which might be easier for you.

I hope this helps,
Adagatiya

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