Item Form Expression Builder

Build an expression visually

When you create or edit an expression, the Item Form Expression Builder will appear.

1 Name

Select to edit the name of the expression. We recommend making it a clear description of what the expression does, so it can be easily picked from a list when someone configures a control property.

2 Node types

Nodes are the building blocks of your expression. Each type represents a function or a value. Values can be static, or dynamically linked to a control property on the item form, or dynamically linked to a global Alloy variable, e.g. the current user's name.

Select a node type in the toolbar to add a node to the canvas.

• ​ Conditionals - logical functions that test inputs from other nodes and produce corresponding output.

• ​ Finals - the expression's output, which will be applied to any control property that targets it.

• ​ Globals - references to the dynamic value of a control property or a global Alloy variable.

• ​ Literals - static values that you input yourself.

• ​ Transforms - functions that modify an input value, producing a new value.

• ​ Dates - functions for creating or manipulating date values.

• ​ Date Times - functions for creating or manipulating date and time values.

For the full list, see Item form expression node types.

3 Tools

Select a tool in the toolbar:

• ​ Delete - delete the currently selected node or link.

• ​ Organise - automatically arrange nodes into formation based on how they're linked.

4 Added nodes

Nodes appear on the canvas as blue boxes, displaying their type and a helpful description of what they do. You can drag them around and use their bottom-right corner to resize them.

To set the value of a node, select its icon and then its Value field.

If it's a Global node, a list of global Alloy variables and compatible control properties will appear. Choose one to link to.

Global Alloy variables

Variable	Description	Global node type
User Alloy ID	The ID of the current user	Alloy ID Array
Item ID	The ID of the item being create/edited	Alloy ID Array
Parent item ID	The IDs of any parent items that link to the item being created/edited	Alloy ID Array
Create mode	Is the item form being used to create an item?	Boolean
Edit mode	Is the item form being used to edit an item?	Boolean
Date Now	The current date	Date
Date Time Now	The current date and time	Date Time
Username	The username of the current user	String
First name	The first name of the current user	String
Last name	The last name of the current user	String
Email	The email address of the current user	String
Customer name	The name of the current customer project	String
Item form name	The name of the current item form	String
Item form context	The context of the current item form	String
Design name	The design name of the item being created/edited	String
Design context	The design context of the item being created/edited	String
Item icon	The icon code of the item being created/edited	String
Item signature	The signature of the item being edited (changes with every edit)	String
Item collection	The Guc of the collection of the item being created/edited	IsTriggering
Item form code	The Guc of the current item form	IsTriggering
Design code	The Guc of the design of the item being created/edited	IsTriggering

If it's a Literal node, you can then provide a value. Depending on the node type, this may involve typing directly into the field, choosing a value from a picker, using the AQS Builder, or enabling/disabling the field to indicate true or false.

5 Links

Define your expression by linking the inputs and outputs of different nodes on the canvas.

Each node has one or more input circles on their left side. They're labelled to help you understand the type of input expected.

Each node has one output circle on their right side (except for final nodes).

To join two nodes together, select an output circle on the first node, and then select an input circle on the second node. When you select a circle, only compatible circles will remain undimmed, so you can only create valid links!

Note

All possible execution branches within the expression should end with a final node.

6 Save button

When you're finished, select Save to save your expression and return to the Item Form Builder. To leave without saving, select in the top-right corner.