ECExpressions

ECExpressions is a very basic language that allows customizing presentation rules' behavior.

Symbols that can be used depend on current context. Example:

this.GetContextB().ContextC.DoSomething()

Here, symbol this returns a context which has a function symbol GetContextB(). This function returns a context which has a property symbol ContextC. And the property value is a context that contains a function symbol DoSomething(). The latter function might return some value or return nothing, but instead do some action - it all depends on the symbol.

ECExpression Syntax

Data types

ECExpressions contain values of primitive types or data type of ECClass or ECArray.

Primitive value types

Type Description Example
Boolean Boolean (true/false) value True, False
DateTime Date and time in ticks @1549278124937
Integer (Long) 32-bit (64-bit) number 1
Double Floating point number 6.84
String String of characters "" ,"Dog and Cat"
Null Null value Null

Other primitive types

Type Description
Binary Array of bytes
Point2d 2D point containing X and Y components as double values
Point3d 3D point containing X, Y and Z components as double values
IGeometry A common geometry value of any type

ECClass data type

ECClass data types define ECInstances. ECClasses contain ECProperties and Methods which can be accessed via dot (.) operator.

ECArray data type

ECArray data types define arrays of values. Each value can be accessed via [] operator.

Expression components

In addition to values of primitive types ECExpressions may contain symbols and operators

Symbols

Symbols are used to supply values to expression evaluator. Symbols can be supplied from ECInstance via an access string, from an application defined value or from application defined method. Access string is a limited expression that holds no blanks, no operators, and no variable portions. It may contain array indexing and member selection using [] or dot . operators, but no part of the expression can be variable, and the access string cannot contain embedded blanks.

Property symbols

ECInstance Property symbols supply Property values of some ECInstance when the symbol is being evaluated.

this.PropertyName
this.StructPropertyName.PropertyName
this.StructArray[5].Struct.PropertyName
Value symbols

Value symbols supply some named predefined value in a context.

System.Math.PI
Method symbols

Method symbols supply a named method in a context.

System.Math.Sin(1.57)
this.IsOfClass("ClassName", "SchemaName")

Operators

Parentheses (,)
(2 * (3 + 4))
Logical operators
Description Operator
Conjunction And*, AndAlso
Disjunction Or*, OrElse
Exclusive disjunction Xor
Negation Not

Note: *Checks right side of expression even if result value can be deducted from the left side.

False And True OrElse True
Comparison operators
Description Operator
Less than <
Less than or equal to <=
Greater than >
Greater than or equal to >=
Equal to =
Not equal to <>
20 < 10 ==> False
Arithmetic operators
Description Operator
Exponentation ^
Multiplication *
Double division /
Integer division \
Modular division Mod
Addition +
Subtraction -
1 + "4"   ==> 5
2.2 * 3   ==> 6.6
12 / 5    ==> 2.4
12 \ 5    ==> 2
25 Mod 3  ==> 1
Bit Shift operators
Description Operator
Signed shift left <<
Signed shift right >>
Unsigned shift right >>>
5 << 1      ==>  10
24 >> 2     ==>  6
-105 >> 1   ==>  -53
-105 >>> 1  ==>  75
Conditional operator
IIf (condition, true-result, false-result)

Returns result based on given condition. If condition evaluates to true, returns true-result. Otherwise returns false-result.

IIf (500>200, "Math ok", "Math wrong") ==> "Math ok"
IIf (500<200, "Math ok", "Math wrong") ==> "Math wrong"
Concatenation operator
"Dog" & " and " & "Cat" ==> "Dog and Cat"
"1" & 4                 ==> "14"
1 & "4"                 ==> "14"
Lambda operator

Lambda operator => creates a callback expression for a given symbol.

MyArray.Find(item => item.IntProperty = 5)

Combined expressions

System.Math.Cos (System.Math.PI * 45.0 / 180.0) ==> 0.707
System.String.Length ("Dog" & " and " & "Cat") ==> 11

Evaluating if property is Null

Method IsNull (value) evaluates if given value is Null.

Method IfNull (value, value-if-null) evaluates to value if it is not null, otherwise evaluates to value-if-null.

In case this.MiddleName is null:

IfNull (this.MiddleName, "") ==> ""
IIf (Not IsNull(this.MiddleName), " " & this.MiddleName & " ", "") ==> ""

In case this.MiddleName is set to "Harvey"

IfNull (this.MiddleName, "") ==> "Harvey"
IIf (Not IsNull (this.MiddleName), " " & this.MiddleName & " ", "") ==> " Harvey "

Checking to see if a this.MiddleName is Null or empty

IIf (IsNull (this.MiddleName) or this.MiddleName = "", "Is null or empty", "Has a value")

ECExpression Contexts

NavNode

Symbol Type Value
IsNull bool Is this context null
Type string Type of the node
Label string Node label
Description string Node description
ClassName string ECClass name if its an EC-related node
SchemaName string ECSchema name if its an EC-related node
SchemaMajorVersion number ECSchema major version if its an EC-related node
SchemaMinorVersion number ECSchema minor version if its an EC-related node
InstanceId number ECInstance ID if its an ECInstance node
IsInstanceNode bool Is this an ECInstance node
IsClassGroupingNode bool Is this an ECClass grouping node
IsPropertyGroupingNode bool Is this an ECProperty grouping node
GroupedInstancesCount number Count of grouped ECInstances (only available for ECClass and ECProperty grouping nodes)
ECInstance ECInstance context ECInstance symbol context if its an ECInstance node
HasChildren bool Does this node have any children
ChildrenArtifacts object[] A value list of objects generated using the NodeArtifacts customization rule on child nodes. Child nodes in this case are immediate child nodes that are not necessarily visible.

ECInstance

ECInstance expression context provides access to ECInstance property values. Example:

this.PropertyName
this.StructPropertyName.PropertyName
this.StructArray[1].Struct.PropertyName

Additionally, when evaluating ECInstance contexts, the below symbols are available:

Symbol Type Value
GetRelatedInstance("RelationshipName:0|1:RelatedClassName") ECInstance context Returns related instance context
GetRelatedInstancesCount("RelationshipSchemaName:RelationshipName", "Forward|Backward", "RelatedClassSchemaName:RelatedClassName") number Number of related instances following the specified relationship
HasRelatedInstance("RelationshipSchemaName:RelationshipName", "Forward|Backward", "RelatedClassSchemaName:RelatedClassName") bool Does this instance has a related instance following the specified relationship
GetRelatedValue("RelationshipSchemaName:RelationshipName", "Forward|Backward", "RelatedClassSchemaName:RelatedClassName", "PropertyName") any Returns property value of the related instance

Symbols in Global Context

Note: User Settings is a deprecated name of Ruleset Variables concept.

Ruleset variable access symbols allow accessing variable values through ECExpressions.

Symbol Deprecated Symbol Type Value
GetVariableStringValue("var_id") GetSettingValue("var_id") string Get string value of a variable with the specified ID
GetVariableBoolValue("var_id") GetSettingBoolValue("var_id") bool Get boolean value of a variable with the specified ID
GetVariableIntValue("var_id") GetSettingIntValue("var_id") number Get int value of a variable with the specified ID
GetVariableIntValues("var_id") GetSettingIntValues("var_id") number[] Get int value list of a variable with the specified ID
HasVariable("var_id") HasSetting("var_id") bool Does variable with the specified ID exist

Other symbols

Symbol Type Value
Set(number1, number2, ..., numberN) number[] Create a value list of the supplied numbers.

Value Lists

Value lists in ECExpressions can be handled with lambdas. Currently the presentation rules engine supports only a single simple lambda for value lists:

value_list.AnyMatch(x => x = this.PropertyValue)

The above expression returns true if value_list contains the value of this.PropertyValue.

Last Updated: 10 September, 2019