topic Re: Civil 3d Expressions in Civil 3D Customization Forum

Civil 3d Expressions

damir_vidakovic — Mon, 15 Feb 2016 09:30:40 GMT

Hi!

I can get created expressions for pipe like this:

ExpressionCollection lblStyleColl = civilDoc.Styles.LabelStyles.PipeLabelStyles.PlanProfileLabelStyles.Expressions;

But, is there a way to get evaluated value for the given expression, for certain pipe entity?

Re: Civil 3d Expressions

augusto.goncalves — Mon, 15 Feb 2016 12:43:27 GMT

Unfortunately there is no API to 'evaluate' these expressions.

Re: Civil 3d Expressions

tony1978 — Wed, 17 Feb 2016 06:03:29 GMT

What exactly are you trying to create?

Re: Civil 3d Expressions

damir_vidakovic — Wed, 17 Feb 2016 07:09:07 GMT

Thank you for your reply.

I'm developing an app that has a possibility to show all entity data, something like properties or panorama, but with all possible data included, like pipe properties, object data, basically everything that can be read from pipe or structure. Civil3d has non unified data for entities (properties from catalog, object data, property sets, properties for entity, and also expressions, that are also a kind of data). Each type is in different place of the program.

Re: Civil 3d Expressions

damir_vidakovic — Wed, 24 Feb 2016 12:58:15 GMT

I'm trying to evaluate expressions by myself, and I have an additional question:

I created the expression, for testing purposes (for pipes) : {Inner Pipe Height}-2 / {Flow Rate}

But, when I open that expression entity from code:

foreach (Autodesk.Civil.DatabaseServices.Styles.Expression lblExp in lblStyleColl)
{
    ed.WriteMessage("\n Expression String : " + lblExp.ExpressionString);
}

I get this as a expressoin string:

{aecc00080000ffff0000ccaeccae0000 Inner Pipe Height}-2/{Flow Rate}

I have no problem detecting pipe data like {Flow Rate}, or any other that is enclosed in {}, but I do not know what means aecc00080000ffff0000ccaeccae0000 in Inner Pipe Height ? Is it always the same, or it can change?

Re: Civil 3d Expressions

Civil3DReminders_com — Tue, 06 Jun 2017 23:27:06 GMT

I add the expression to a label as a text override, explode the label, and then grab the exploded contents to find the value.

Re: Civil 3d Expressions

damir_vidakovic — Wed, 07 Jun 2017 08:41:29 GMT

I believe that this approach could work in some scenarios, but if you have a larger system, this operation would be slow. And if I have multiple expressions for an entity, it could get very bad.

I finally implemented my own expression solver, by parsing expression formulas and substituting variables with actual values, by using NCalc expression solver.