CE Display Rules C#

Hi Salvatore,

can you provide a DGN as an example, what would be expected result? I guess something like ItemType attached to an element plus display rule defined in some style...

Regards,

  Jan

DisplayRules.dgn

For this file I would like to create a condition that allows me to select the shape (the larger one to which an ItemType is attached) where the value of the L08_SHIP_ZONE property is = "FOO".
Something like:
string MyRuleCondition = @"element.DgnElementSchema::ShapeElement::IDES_ITEMTYPE.L08_SHIP_ZONE = ""FOO""";

Thanks for the help, greetings

salvatore montella said:

For this file I would like to create a condition that allows me to select the shape (the larger one to which an ItemType is attached) where the value of the L08_SHIP_ZONE property is = "FOO".

Are you able to do it (configure the display rule) manually?

Regards,

  Jan

Yes

salvatore montella said:

Yes

Thanks for the confirmation, I was able to modify your example accordingly (manually).

DisplayRules_ManualConfig.dgn

In this file there is the display rule configured manually

Hi Salvatore,

salvatore montella said:

string MyRuleCondition = @"element.DgnElementSchema::ShapeElement::IDES_ITEMTYPE.L08_SHIP_ZONE = ""FOO""";

an idea, without writing any test code

Because as noted in documentation you linked, the format is

HostName.SchemaName::ClassName::Propertyname OPERATOR VALUE

I assume the definition cannot be based on DgnElementSchema, because it's not schema defining ItemType you attached.

Maybe something like

element.DgnCustomItemTypes_IDES_TYPELIBRARY::IDES_ITEMTYPE::L08_SHIP_ZONE = "FOO"

With regards,

  Jan

Hi Jan, your suggestion resolved my issue.
I was not able to figure how to determine the schema name of the ItemTypeLibary in the condition's expression.

Since there is no match between the condition expression shown in the user's interface and the expression required in code I don't know how to write the condition's expression.

E.G. "ELEMENT Is Shapes" in the UI became "element.IsOfClass ("ShapeElement","DgnElementSchema")" in the code.

Is there a reference guide describing the schemas and the expression syntax?

Best regards

Hi salvatore,

salvatore montella said:

I was not able to figure how to determine the schema name of the ItemTypeLibary in the condition's expression.

it's "simple" (when you know it :-) ). When you need to know intrinsict (stored in DGN file) EC schemas, and ItemTypes EC schemas are alwayas intrinsict, use "ecx schema list" key-in, that lists the schemas to Message Center Details.

Graphical elements features like color etc. are defined in extrinsict EC schema DgnElementSchema.

salvatore montella said:

Since there is no match between the condition expression shown in the user's interface and the expression required in code

There is no reason why there should be the match. It seems description is filled automatically by a summary, but it's not the condition syntax.

salvatore montella said:

I don't know how to write the condition's expression.

Well ... as written in the documentation you linked: DisplayRule condition is based on ECExpression. I agree it tells nothing for a plain user, and also for developers it's not clear for 100% (because "is based on" expresses that it's only a subset of ECExpression). But at least, it's defines the basic syntax format.

salvatore montella said:

Is there a reference guide describing the schemas and the expression syntax?

I think the description provided in DisplayRule API documentation is where you should start. Despite of it's short, I think it covers the most of needs and scenarios.

Two other sources are:

• Search this web (and Internet in general) for ECExpression. Because this technology has existed in Bentley products for many (maybe 15?) years already, it's possible to fined some valuable blogs and articles (e.g. this one). But be aware it's not specified that Display Rules support complete ECExpression (plus some features of ECE are not conditions).
• Read how conditions are defined in Item Types (now in Technology Preview phase), because they are, again, ECExpressions.

The problem is that without good knowledge of the whole "EC world" (which is very wide and complex topic), some concepts behind and terminology will remain unexplained.

With regards,

  Jan

the link

https://docs.bentley.com/LiveContent/web/MicroStation%20Help-v15/en/BetaExpressions.html

doesn't exist?  Just goes to Bentley docs.
Can you give the proper link or is this another link only available to Bentley employees?
Which Bentley Doc lists the Beta Expressions?

Display rules use ECExpressions?
Does that mean you can use string.empty  as an empty string value in Item display rules?
Or IsNullOrEmpty?

tried to use the above, but didn't work for me, only the workaround did.
CE update 14.

Wouldn't ECExpression SymbolSet System.String need to be loaded to use string ECExpressions?

communities.bentley.com/.../ecexpressions-explained-calculated-ecproperty

 think there should be a simpler list of what expressions if any that you can use in Display Rules.

Karsten EVANS said:

CE update 14

Expressions have advanced in recent versions of MicroStation CONNECT.  You'll find plenty by searching for Expressions in Update 16 help.

If you're looking to create a display rule programmatically, then start with the C++ MicroStationAPI documentation.  For example...

DisplayRuleSetPtr ruleSet = DisplayRuleSet::Create(L"RuleSetName", *dgnFile_);

DisplayRulePtr MakeRule (WCharCP itemTypeName, WCharCP propName, WCharCP condition)
{
  WString prop (propName);
  WString rule;
  rule.Sprintf (L"element.%s::%s::%s%s",
    ItemTypes::SchemaInternalName ().c_str (),
    ItemTypes::GetInternalName (itemTypeName).c_str (),
    propName,
    condition);
  return MakeRule(rule.c_str ());
}

DisplayRulePtr    MakeRule (WCharCP rule)
{
  const bool    StopIfTrue    {true};
  DisplayRulePtr  displayRule   {DisplayRule::Create(rule, StopIfTrue , *dgnFile_)};
  const bool    valid      {displayRule.IsValid ()};
  if (valid)
  {
    // Created Display Rule:  rule
  }
  else
  {
    // Display rule instruction rule is invalid
  }
  return displayRule;
}

Karsten EVANS said:

CE update 14

Expressions have advanced in recent versions of MicroStation CONNECT.  You'll find plenty by searching for Expressions in Update 16 help.

If you're looking to create a display rule programmatically, then start with the C++ MicroStationAPI documentation.  For example...

DisplayRuleSetPtr ruleSet = DisplayRuleSet::Create(L"RuleSetName", *dgnFile_);

DisplayRulePtr MakeRule (WCharCP itemTypeName, WCharCP propName, WCharCP condition)
{
  WString prop (propName);
  WString rule;
  rule.Sprintf (L"element.%s::%s::%s%s",
    ItemTypes::SchemaInternalName ().c_str (),
    ItemTypes::GetInternalName (itemTypeName).c_str (),
    propName,
    condition);
  return MakeRule(rule.c_str ());
}

DisplayRulePtr    MakeRule (WCharCP rule)
{
  const bool    StopIfTrue    {true};
  DisplayRulePtr  displayRule   {DisplayRule::Create(rule, StopIfTrue , *dgnFile_)};
  const bool    valid      {displayRule.IsValid ()};
  if (valid)
  {
    // Created Display Rule:  rule
  }
  else
  {
    // Display rule instruction rule is invalid
  }
  return displayRule;
}