Formula Editor having issue in ModernUI

Hey ​@ashrivastava42 , I don’t have the answer to this, but I have a requirement to implement a custom formula field (classic UI), and I am trying to find documentation on this. 

I have two questions right now that I would appreciate help with.

1.  What exactly does the “GetAllParameters()” method return?
2. How is this formula evaluated at runtime, with the current field values passed to those parameters?

Any help is greatly appreciated. 

I’ve looked at the article on adding custom DAC objects to the formula builder, but I don’t believe that’s what I need. I just want to add to the “Field” sections, and then evaluate expressions that use values I pass in at runtime. 

​@MichaelShirk - Because I know what you’re attempting to do, you’ll need something like this:

[PXMergeAttributes(Method = MergeMethod.Append)]
[PXFormulaEditor_AddFields]
protected virtual void _(Events.CacheAttached<DXPRSetupExt.usrMyFormulaField> e) { }

public class PXFormulaEditor_AddFieldsAttribute : PX.Data.PXFormulaEditor.OptionsProviderAttribute
{
    public override void ChangeOptionsSet(PXGraph graph, ISet<FormulaOption> options)
    {
        AddFields<BAccount>(graph, options);
        AddFields<Contact>(graph, options);
        AddFields<Address>(graph, options);
    }

    void AddFields<T>(PXGraph graph, ISet<FormulaOption> options) where T : class, IBqlTable, new()
    {
        Type type = typeof(T);

        foreach (string field in GetFields<T>(graph))
        {
            // Skip attributes because we've not implemented them
            // TODO : Implement attributes
            if (field.EndsWith("_Attributes")) continue;

            options.Add(new FormulaOption
            {
                Category = $"Fields",
                Value = $"[{type.Name}.{field}]"
            });
        }
    }
}

private static string[] GetFields<T>(PXGraph graph) where T : class, IBqlTable, new()
{
    var select = new SelectFrom<T>.View(graph);

    return select.Cache.Fields.ToArray();
}

Hi ​@ashrivastava42,

As the formula editor itself is loading fine, I just tested by hardcoding the field names like below which brings up the values in the formula editor, 

public class FeatureMaint_Extension : PXGraphExtension<PX.Objects.AM.FeatureMaint>
    {
        #region Event Handlers
        [ConfigFormulaEditor(DisplayName = "UsrcustValue")]
        [PXFormulaEditor_AddFieldsExt]
        protected virtual void _(Events.CacheAttached<AMFeatureOptionExt.usrcustValue> e) { }
        #endregion

        protected class PXFormulaEditor_AddFieldsExtAttribute : PXFormulaEditor.OptionsProviderAttribute
        {
            public override void ChangeOptionsSet(PXGraph graph, ISet<FormulaOption> options)
            {

                var designer = (FeatureMaint)graph;
                foreach (var parameter in designer.GetAllAttributes())
                {
                    options.Add(new FormulaOption
                    {
                        Category = $"Fields",
                        Value = parameter
                    });
                }

                var g = (FeatureMaint)graph;
                var fields = new List<string> { "FieldOne", "FieldTwo", "FieldThree", "FieldFour" };

                foreach (var parameter in fields)
                {
                    options.Add(new FormulaOption
                    {
                        Category = "Fields",
                        Value = parameter
                    });
                }
            }
        }
    }

For us to check this further, can you please share a small customization project using which we can reproduce the issue?