Understanding Uniface 10.4 structToComponent: Converting Data Structures into Components 🚀

This blog post was created with AI assistance to help developers understand this powerful Uniface feature.

What is structToComponent? 🤔

The structToComponent statement in Uniface 10.4 is a powerful function that converts data from a Struct (structure) or collection of Structs into entities and occurrences within a component. Think of it as a bridge that takes hierarchical data and loads it directly into your component's data structure.

Understanding Key Terms 📚

Before diving deeper, let's clarify some important terms:

• Struct: A tree-like data structure in memory used to manipulate complex data dynamically
• Component: In Uniface, a reusable software object that encapsulates data and behavior
• Entity: A logical grouping of related data fields, similar to a database table
• Occurrence: A single record or instance of an entity, like a row in a database table
• 4GL: Fourth Generation Language - a high-level programming language that requires minimal coding

Basic Syntax and Usage 📝

The basic syntax for structToComponent is straightforward:

structToComponent {/firetriggers} StructSource

Example:

structToComponent vStruct

The /firetriggers Qualifier ⚡

The optional /firetriggers qualifier causes preDeserialize and postDeserialize triggers to fire during the conversion process. These triggers allow you to add custom processing logic:

• preDeserialize: Fired before an occurrence is loaded into the component
• postDeserialize: Fired after an occurrence is loaded, allowing you to modify or validate the loaded data

How Name Matching Works 🎯

The structToComponent function uses intelligent name matching rules:

• Tag names (annotations) are case-sensitive
• Entity and field names can be non-qualified (ENTITYNAME), partially qualified (FIELDNAME.ENTNAME), or fully qualified (ENTITY.MODEL)
• If names are ambiguous, you must use fully qualified names or u_type tags to specify object types

Practical Example: Creating and Converting Data 💡

Here's a simple example that demonstrates how to create a Struct and convert it to component data:

function createStruct
variables
 struct vStruct, vFld
endvariables
 ; Create a Struct with field names and values
 vFld->ORDERNUM = 101
 vFld->SHIPTO = "Chicago"
 ; Create a Struct named ORDERS
 vStruct->$name = "ORDERS"
 ; Assign the Field Struct to a new member called OCC
 vStruct->OCC = vFld
 PUTMESS_OUTPUT = vStruct->$dbgstring 
 structToComponent vStruct
end

This code creates a simple order structure with an order number and shipping location, then converts it into the component's data structure.

Understanding Struct Annotations 🏷️

Uniface uses special annotation tags to help with data conversion [web:2]:

Tag	Allowed Values	Purpose
u_type	component \	entity \
u_id	OccID	Uniface-generated occurrence identifier
u_status	est \	mod \

Error Handling and Return Values ⚠️

The function returns status information in $status:

• 0: Struct successfully converted
• <0: An error occurred (check $procerror for details)

Common errors include:

• -1905 (STRUCTERR_INPUT): Input struct data is not valid

Working with Reconnect Data 🔄

If your Struct contains reconnect processing tags (created with componentToStruct/reconnecttags), structToComponent can handle disconnected record sets. After using structToComponent, you should immediately use a reconnect statement to:

• Remove duplicate occurrences
• Remove occurrences marked for deletion
• Set appropriate modification flags

Real-World Applications 🌟

structToComponent is particularly useful for:

• Data Integration: Converting external data formats (JSON, XML) into Uniface components
• Web Services: Processing data received from REST APIs
• Data Synchronization: Handling disconnected datasets in distributed applications
• Legacy System Migration: Converting data from older systems into modern Uniface applications

Best Practices and Tips 💪

When working with structToComponent, keep these recommendations in mind:

• Always check the return status and handle errors appropriately
• Use fully qualified names when dealing with complex data structures
• Consider memory usage when working with large Structs
• Use the /firetriggers qualifier when you need custom processing logic
• Follow up with reconnect when working with disconnected data

Conclusion 🎉

The structToComponent function is an essential tool for Uniface developers working with complex data transformations. It provides a robust way to convert hierarchical data structures into component data, enabling seamless integration with external systems and efficient data manipulation. Whether you're building modern web applications or maintaining legacy systems, understanding structToComponent will help you handle data conversion tasks more effectively.

Uniface's low-code approach combined with powerful functions like structToComponent continues to make it a valuable platform for enterprise application development. As organizations face the challenge of modernizing legacy applications while maintaining business continuity, tools like these provide the flexibility needed to evolve systems gradually.