Predicates

A Predicate is a high-level, logical test that defines the syntax for Rules.

Test

Predicate	Description	Parameter(s)	Returns
Check That	A comparison between two values using a relationship and returns true or false to indicate whether the values fulfil the relationship. The data types of values that can be used depends on the relationship.	N/A	Value Relation Value
Reference	Check that two objects are related via a reference e.g. a Foreign Key. Specify the two objects and the name of the reference between them. The Predicate is satisfied if the first object refers to the second object using the given reference.	Class 1 Name 1 (optional) Ref Name Class 2 Name 2 (optional)	N/A
Test in Range	Check that the first value lies in the range between the second and third values. Use the Include Upper/Lower Endpoint check boxes in the right hand panel to specify whether or not the end points of the range should be included in the comparison. The values can be Integers, Reals or Strings. Example: Setting the minimum value as 5 and the maximum as 10 without selecting either endpoint option would only include 6-9 in the range.	Include Upper Endpoint Include Lower Endpoint	Value (to test) Value (range minimum) Value (range maximum)

Predicate

Description

Parameter(s)

Returns

Check That

A comparison between two values using a relationship and returns true or false to indicate whether the values fulfil the relationship.

The data types of values that can be used depends on the relationship.

N/A

Value
Relation
Value

Reference

Check that two objects are related via a reference e.g. a Foreign Key.

Specify the two objects and the name of the reference between them.

The Predicate is satisfied if the first object refers to the second object using the given reference.

Class 1
Name 1 (optional)
Ref Name
Class 2
Name 2 (optional)

N/A

Test in Range

Check that the first value lies in the range between the second and third values.

Use the Include Upper/Lower Endpoint check boxes in the right hand panel to specify whether or not the end points of the range should be included in the comparison.

The values can be Integers, Reals or Strings.

Example: Setting the minimum value as 5 and the maximum as 10 without selecting either endpoint option would only include 6-9 in the range.

Include Upper Endpoint
Include Lower Endpoint

Value (to test)
Value (range minimum)
Value (range maximum)

Static

Predicate	Description	Parameter(s)	Returns
Cast	The cast node allows you to assert that you know that an object will be a specific class, or that you want to pretend it is of that class. This allows you to use attributes from that class in the Rule or Action builder that would not show them otherwise. See Cast Node for more information.	From Class From Name (optional) To Class To Name (optional)	N/A
False	Always evaluates as false.	N/A	N/A
True	Always evaluates as true.	N/A	N/A

Branch

Predicate	Description	Parameter(s)	Returns
Execute then Check	Execute the operation, then check the predicate.	N/A	Predicate Operation
If…Then…Else	This must have two or three child Predicates. The first Predicate is checked and if it holds then the overall result is the result of checking the second Predicate. Otherwise, if the first Predicate does not hold, the overall result is the result of checking the third Predicate, or true if the third Predicate is omitted.	N/A	Predicate 1 Predicate 2 Predicate 3 (optional)
Try…Catch	Returns the Try Predicate unless it throws an exception, in which case it will return the Catch Predicate. Useful to trap errors which would otherwise stop the object iteration or the session from continuing. Example: A string representing a date may not be valid when calling a function to convert it to a timestamp. Use this value to catch the error, use null instead and continue without an error.	N/A	Predicate 1 Predicate 2

Predicate

Description

Parameter(s)

Returns

Execute then Check

Execute the operation, then check the predicate.

N/A

Predicate
Operation

If…Then…Else

This must have two or three child Predicates.

The first Predicate is checked and if it holds then the overall result is the result of checking the second Predicate.

Otherwise, if the first Predicate does not hold, the overall result is the result of checking the third Predicate, or true if the third Predicate is omitted.

N/A

Predicate 1
Predicate 2
Predicate 3 (optional)

Try…Catch

Returns the Try Predicate unless it throws an exception, in which case it will return the Catch Predicate.

Useful to trap errors which would otherwise stop the object iteration or the session from continuing.

Example: A string representing a date may not be valid when calling a function to convert it to a timestamp. Use this value to catch the error, use null instead and continue without an error.

N/A

Predicate 1
Predicate 2

Template

Predicate	Description	Parameter(s)	Returns
Rule Template	Import a Rule Template from your Rule and Action Templates The Template parameter allows you to choose existing Rule Templates from the dialog that appears. This only shows Rule Templates and folders that contain them.	Template	Dependent on the template

Predicate

Description

Parameter(s)

Returns

Rule Template

Import a Rule Template from your Rule and Action Templates

The Template parameter allows you to choose existing Rule Templates from the dialog that appears. This only shows Rule Templates and folders that contain them.

Template

Dependent on the template

Collection

Predicate	Description	Parameter(s)	Returns
Existence in Collection	Checks whether the required number of elements exist in an object collection or an array that match the Predicate in the clause. A Qualifier must be set, with the options: At Least: The number of elements matching the predicate must be at least equal to the quantity value. At Most: The number of elements matching the predicate must be at most equal to the quantity value. Exactly: The number of elements matching the predicate must be equal to the quantity value.	Qualifier Quantity Class Name (optional)	Value (collection name) Predicate
For All in Collection	Checks all objects or elements in a collection satisfy a Predicate. The Predicate requires a value which should be an array or a collection of objects, and a Predicate to check. For a collection of simple types, or objects of unspecified class, the class label may be omitted. Otherwise the class label specifies the type of object in the collection.	Class Name	Value Predicate

Predicate

Description

Parameter(s)

Returns

Existence in Collection

Checks whether the required number of elements exist in an object collection or an array that match the Predicate in the clause.

A Qualifier must be set, with the options:

At Least: The number of elements matching the predicate must be at least equal to the quantity value.
At Most: The number of elements matching the predicate must be at most equal to the quantity value.
Exactly: The number of elements matching the predicate must be equal to the quantity value.

Qualifier
Quantity
Class
Name (optional)

Value (collection name)
Predicate

For All in Collection

Checks all objects or elements in a collection satisfy a Predicate.

The Predicate requires a value which should be an array or a collection of objects, and a Predicate to check.

For a collection of simple types, or objects of unspecified class, the class label may be omitted. Otherwise the class label specifies the type of object in the collection.

Class
Name

Value
Predicate

Boolean

Predicate	Description	Parameter(s)	Returns
AND	Logical AND Predicate. Used to combine two or more other predicates (supplied as child objects) and check that they are all true.	N/A	Predicate 1 Predicate 2 …add with Add icon Predicate N
NOT	Logical NOT Predicate. Used to invert the result of another Predicate (supplied as a child object). For example, if the child Predicate is true, this Predicate returns false and vice-versa.	N/A	Predicate
OR	Logical OR Predicate. Used to combine two or more Predicates and will pass if any of them are true.	N/A	Predicate 1 Predicate 2 … add with Add icon Predicate N
XOR	Logical "exclusive or" Predicate. Takes two or more Predicates as inputs. When two are provided it will pass if one is true. When providing more than two Predicates, it will only pass if an odd number of the conditions are true.	N/A	Predicate 1 Predicate 2 … add with Add icon Predicate N

Loop

Predicate	Description	Parameter(s)	Returns
Chain	Check whether there is a chain of segments of the class specified between a source and a target feature.	Limit Segment class Seed name Target name Prior name Posterior	Predicate
Existence	This can be used to check for the existence (or absence) of related objects satisfying a Predicate specified in a clause. The objects in the clause are identified by the class and object label pair. You specify a qualifier ("at least", "at most", or "exactly"), a number of objects and another class name. The Predicate checks that at least one object exists where the child Predicate returns True. To check for the absence of objects satisfying a Predicate, look for exactly 0 objects.	Qualifier Quantity Class Name (optional)	Value Predicate
For All	Check that all related objects satisfy some other Predicate. This Predicate must have two child Predicates. The first Predicate filters a set of objects, the second Predicate then checks that these objects meet certain requirements.	Class Name (optional)	Predicate (filter) Predicate (check)
For the Nearest	For the nearest n objects, check that they satisfy another Predicate. There can be three child elements: A source geometry from which to measure distance An optional Predicate, which allows additional filter Predicates on the nearest objects. The Predicate to check. A check is then made on the objects to see if they satisfy the second child Predicate. If using the optional filter, only the objects that pass the filter are tested with the second Predicate.	Class Name (optional)	Value (count) Predicate (optional) Predicate (check)