The Complete Guide to Placeholders in Business Rules

Introduction

Imagine showing a user an error message that says: "Value exceeds limit." While technically informative, it leaves users asking critical questions: Which value? What limit? By how much? What should I do?

Now imagine showing: "Credit limit exceeded. Customer ACME Corp has credit limit $50,000 but current balance $45,000 plus this order $10,000 would total $55,000, exceeding the limit by $5,000. Please reduce order amount, collect payment, or request credit limit increase."

The difference? Placeholders—dynamic field references that transform generic messages into specific, actionable, helpful communications that empower users to resolve issues immediately.

Placeholders are one of the most powerful yet underutilized features of QUALIA Rule Engine. This comprehensive guide explains what placeholders are, how they work, where you can use them, advanced techniques for complex scenarios, troubleshooting common issues, and best practices for creating messages that users actually appreciate.

What Are Placeholders?

Definition

A placeholder is a dynamic reference to a field value that gets replaced with the actual data when the rule executes.

Syntax: [TableNumber:FieldNumber]

Example:

• [18:2] → Customer Name from table 18, field 2

• [36:109] → Amount Including VAT from table 36, field 109

• [27:3] → Item Description from table 27, field 3

How Placeholders Work

When QUALIA Rule Engine processes a rule action with placeholders:

1. Rule condition evaluates to TRUE

2. Action is triggered (Error, Warning, Email, etc.)

3. Engine identifies placeholders in action text (anything in [TableNo:FieldNo] format)

4. For each placeholder:

   • Lookup table number

   • Access specific field

   • Retrieve current field value

   • Replace placeholder with actual value

5. Final message displayed to user with all placeholders resolved

Example execution:

Message template:
"Order amount $[36:109] would exceed credit limit $[18:59]"

At runtime:
- [36:109] is replaced with actual order amount: 55000
- [18:59]

Why Placeholders Are Critical

Without placeholders (static messages):

With placeholders (dynamic messages):

Error: "Credit limit exceeded. Customer [18:2] has credit limit $[18:59] 
but current balance $[18:61] plus this order $[36:109] would total 
$([18:61] + [36:109]), exceeding the limit by $([18:61] + [36:109] - [18:59]).

Please reduce order amount to $([18:59] - [18:61]

Benefits:

• ✅ Users understand the specific issue

• ✅ Users see relevant data values

• ✅ Users know how to resolve the problem

• ✅ Reduces support tickets

• ✅ Faster problem resolution

• ✅ Better user experience

Placeholder Syntax and Components

Basic Syntax

Format: [TableNumber:FieldNumber]

Components:

• Opening bracket: [

• Table number: Business Central table number (integer)

• Colon separator: :

• Field number: Business Central field number (integer)

• Closing bracket: ]

Examples:

[18:1]    → Customer No. (Table 18, Field 1)
[18:2]    → Customer Name (Table 18, Field 2)
[18:59]   → Credit Limit (Table 18, Field 59)
[36:3]    → Document No. (Table 36, Field 3)
[36:109]  → Amount Including VAT (Table 36, Field 109)
[27:8]

Common Business Central Tables Referenced:

• Table 18 - Customer: No. (1), Name (2), Credit Limit (59), Balance (61), Payment Terms (27), Blocked (39)

• Table 36 - Sales Header: No. (3), Document Type (1), Amount Including VAT (109), Status (120), Order Date (99)

• Table 27 - Item: No. (1), Description (3), Unit Price (18), Unit Cost (21/22), Base Unit of Measure (8)

Finding Table and Field Numbers

Method 1: Business Central Table Browser

1. Search for "Tables" in Business Central

2. Find your table (e.g., "Sales Header")

3. Note table number (e.g., 36)

4. Open table

5. Show fields

6. Find your field (e.g., "Amount Including VAT")

7. Note field number (e.g., 109)

Method 2: QUALIA Rule Engine Field Helper

1. In Rule Set, navigate to Conditions or Actions

2. Use Field Lookup feature (if available)

3. Select table

4. Select field

5. System inserts correct placeholder syntax

Method 3: Business Central Documentation

• Official Microsoft documentation lists table and field numbers

• Community resources and forums

• BC object browser extensions

Common Business Central Tables (Reference):

Case Sensitivity and Spacing

Placeholders are NOT case-sensitive (generally):

[18:2]    ✓ Works
[18:2]

Spacing is NOT allowed inside brackets:

[18:2]      ✓ Correct
[ 18:2 ]    ✗ May not work (spaces inside brackets)
[18: 2]     ✗ May not work (space after colon)
[ 18 : 2 ]

Best practice: Use no spaces, consistent formatting: [TableNo:FieldNo]

Where Placeholders Can Be Used

1. Error Messages

Purpose: Explain why transaction is blocked with specific data

Syntax:

Action Type: Error
Message: "Your message with [TableNo:FieldNo]

Example:

Message: "Cannot create order. Customer [18:2] is blocked for [18:40]

Placeholders Used:

• [18:2] - Customer (Table 18): Name (Field 2) - Customer name

• [18:40] - Customer (Table 18): Blocked (Field 40) - Blocked reason (e.g., Ship, Invoice, Payment, All)

Best practices for error messages:

• Explain what's wrong

• Show relevant data values

• Provide specific resolution steps

• Include contact information if needed

2. Warning Messages

Purpose: Alert user to potential issue but allow them to proceed

Syntax:

Action Type: Warning
Message: "Your message with [TableNo:FieldNo]

Example:

Message: "Unit price $[37:22] is below standard price $[27:18]. 
Margin is only [([37:22] - [27:21]) / [37:22] * 100]%. 
Confirm you want to proceed with this pricing."

User sees:
"Unit price $45.00 is below standard price $50.00. 

**Placeholders Used:**

Best practices for warnings:

• Explain the unusual condition

• Provide context with data

• Allow user to make informed decision

3. Confirmation Messages

Purpose: Ask user to confirm an action with specific details

Syntax:

Action Type: Confirmation
Message: "Your message with [TableNo:FieldNo]

Example:

Message: "This order for $[36:109] exceeds typical order size of $[18:73] 
for customer [18:2]

4. Email Notifications

Purpose: Send detailed notifications to stakeholders

Syntax:

Action Type: Email
To: recipient@company.com
Subject: "Subject with [TableNo:FieldNo]"
Body: "Message body with [TableNo:FieldNo]

Example:

To: salesmanager@company.com
Subject: "Large Order Created: $[36:109]"
Body: "Sales order [36:3] was created by [USERID] for customer [18:2] 
with amount $[36:109]. 

Order details:
- Customer: [18:2] ([18:1])
- Amount: $[36:109]
- Payment Terms: [36:64]
- Requested Delivery: [36:76]
- Salesperson: [36:43]

Best practices for email notifications:

• Clear, descriptive subject line

• Structured body with key information

• Include relevant context

• Provide actionable information

5. Message Actions (Informational)

Purpose: Provide information without blocking transaction

Syntax:

Action Type: Message
Message: "Your message with [TableNo:FieldNo]

Example:

Message: "Customer [18:2] has outstanding balance of $[18:61]. 
Current payment terms are [18:27]

6. Field Assignments

Purpose: Auto-populate fields with calculated or referenced values

Syntax:

Action Type: Assign
Field: [TargetTableNo:TargetFieldNo]
Value: [SourceTableNo:SourceFieldNo]

Example 1: Simple assignment:

Action: Assign
Field: Salesperson Code [36:43]
Value: [18:30]

Example 2: Calculated assignment:

Action: Assign
Field: Discount Amount [36:176]
Value: [36:109]

Note: Not all field types support placeholder-based assignment. Verify in QUALIA Rule Engine documentation.

7. URL Actions

Purpose: Provide links to external systems with dynamic parameters

Syntax:

Action Type: URL
URL: "https://system.com/page?param=[TableNo:FieldNo]

Example:

URL: "https://crm.company.com/customer?id=[18:1]&name=[18:2]

Advanced Placeholder Techniques

Calculations with Placeholders

Placeholders can be used in arithmetic expressions:

Operators:

• + Addition

• - Subtraction

• * Multiplication

• / Division

Example: Calculate total:

Message: "Order total including balance: $([36:109] + [18:61]

Example: Calculate difference:

Message: "You are over limit by $([36:109] + [18:61] - [18:59]

Example: Calculate percentage:

Message: "Discount percentage: [([36:176] / [36:109]

Example: Complex calculation:

Message: "Margin: [(([37:22] - [27:21]) / [37:22]

Order of operations: Standard mathematical precedence (parentheses, multiplication/division, addition/subtraction)

Formatting Placeholders

Currency formatting:

In many systems, append currency symbol:
"$[36:109]" → "$125,000.00"

Or use locale-specific formatting:
"Amount: [36:109]

Note: Formatting capabilities depend on QUALIA Rule Engine implementation. Check documentation for supported formatting options.

Percentage formatting:

"[([36:176] / [36:109]

Date formatting:

"[36:99]

Decimal places: System typically formats based on field definition in Business Central.

Conditional Placeholders (Text Logic)

Use case: Show different text based on field value

Approach: Use multiple rules with different conditions and messages

Example:

Rule 1:
Scenario 1: [18:39] is true
Scenario 2: [18:40] is 'Payment'
Message: "Customer [18:2] is blocked for Payment. Contact accounting at ext. 2000."

Rule 2:
Scenario 1: [18:39] is true
Scenario 2: [18:40] is 'Shipment'
Message: "Customer [18:2] is blocked for Shipment. Contact shipping at ext. 3000."

Rule 3:
Scenario 1: [18:39] is true
Scenario 2: [18:40] is 'All'
Message: "Customer [18:2]

Each rule fires for different blocking reasons with appropriate message and contact info.

Multi-Table Placeholders

Use linked tables to reference related data:

Example: Sales Order referencing Customer and Item:

Trigger Table: Sales Line (37)
Linked Tables: 
  - Sales Header (36)
  - Customer (18)
  - Item (27)

Message: "Item [27:3] for customer [18:2] at price $[37:22]. 
Standard price is $[27:18], cost is $[27:21]. 
Order total is $[36:109]

Table linking requirements:

• Linked tables must be configured in Source References

• Appropriate filters must exist to link tables

• Fields from linked tables accessible via their table numbers

Placeholder in Subject Lines

Email subjects should be concise but informative:

Poor subject:
"Notification"

Better subject:
"Order Created"

Best subject:
"Order [36:3] Created: $[36:109]

Nested Calculations

Complex business logic can use nested expressions:

Message: "Effective price after discount: 
$([37:22] - ([37:22] * [37:11]

Another example:

Message: "Available credit: 
$([18:59] - ([18:61] + [36:109]

Troubleshooting Placeholders

Problem: Placeholder Not Replaced (Shows Literal [18:2])

Symptoms: Message shows [18:2] instead of "ACME Corp"

Possible causes:

1. Incorrect syntax:

[18:2]     ✓ Correct
(18:2)     ✗ Wrong brackets
{18:2}     ✗ Wrong brackets
[18-2]     ✗ Wrong separator
[18.2]

2. Spaces in placeholder:

[18:2]     ✓ Correct
[ 18:2 ]   ✗ Spaces inside
[18 : 2]

3. Wrong table or field number:

[18:2]     ✓ Correct (Customer Name exists)
[18:999]   ✗ Field 999 doesn't exist in table 18
[999:2]

4. Linked table not configured:

• If placeholder references table other than trigger table

• Ensure table is in Source References

• Ensure link filters are correct

Debugging:

• Check Validation Log for placeholder resolution

• Verify table and field numbers in Business Central

• Verify linked table configuration

• Test with simpler placeholder first

Problem: Placeholder Shows Blank or Zero

Symptoms: Placeholder resolves but shows empty value or zero

Possible causes:

1. Field is actually blank:

• Verify field has value in the record

• Check if field is populated at trigger event timing

2. Wrong field number:

• Verify correct field number

• Easy to confuse similar field names

3. Linked table filter doesn't match:

• No matching record in linked table

• Filter configuration error in Source References

4. Timing issue with Before Insert:

• Field not yet populated when Before Insert fires

• Some fields populated after insert

• Use After Insert if needed

Debugging:

• Check actual field value in Business Central

• Verify field value exists at trigger timing

• Test with different field that definitely has value

• Review linked table filter configuration

Problem: Calculation Placeholder Shows Wrong Result

Symptoms: [36:109] + [18:61] shows incorrect total

Possible causes:

1. Order of operations:

[36:109] + [18:61] * 2
// Multiplication happens first: 18:61 * 2, then adds 36:109

Intended:
([36:109] + [18:61]

2. Division by zero:

[36:109] / [36:110]
// If field 110 is zero, may show error or infinity

Safe version:
[36:109] / ([36:110]

3. Data type mismatch:

• Integer division truncates decimals

• Check field data types

4. Field units mismatch:

[27:18] - [27:22]

Debugging:

• Test each placeholder individually

• Verify data types

• Check field units

• Use parentheses to control order

• Test with known values

Problem: Placeholder in Email Not Resolving

Symptoms: Email received with literal [18:2] instead of customer name

Possible causes:

1. Email system doesn't support placeholders:

• Verify QUALIA Rule Engine version supports placeholders in emails

• Check documentation for email action capabilities

2. Email sent before placeholder resolution:

• Timing issue in rule engine

• May be bug or limitation

3. Email template vs. dynamic content:

• Some systems distinguish between template and dynamic content

• Verify correct field for dynamic content

Debugging:

• Test with simple placeholder first

• Check if any placeholders work in email

• Review QUALIA Rule Engine documentation for email action

• Test with Message action first (known to support placeholders)

Problem: Special Characters in Placeholder Value

Symptoms: Placeholder value contains quotes, brackets, or special characters causing display issues

Example:

Customer Name: "Bob's "Special" Company [LLC]"
Placeholder: [18:2]
Message: "Customer [18:2]

Solution:

• QUALIA Rule Engine should handle this automatically

• If issues occur, report as potential bug

• Consider using different field (e.g., Customer No. instead of Name)

Best Practices for Using Placeholders

1. Always Provide Context

Poor:

Better:

"Credit limit $[18:59]

Best:

"Credit limit exceeded. Customer [18:2] has credit limit $[18:59] 
but this order $[36:109] plus current balance $[18:61] totals 
$([36:109] + [18:61]), exceeding limit by $([36:109] + [18:61] - [18:59]

2. Show Both Problem and Solution

Poor:

Best:

"Credit limit exceeded. Customer [18:2] has credit limit $[18:59] 
but this order $[36:109] plus current balance $[18:61] totals 
$([36:109] + [18:61]).

To proceed:
- Reduce order amount to $([18:59] - [18:61]

3. Use Descriptive Text Around Placeholders

Poor:

"[18:2] [18:59] [18:61]

Best:

"Customer [18:2] has credit limit $[18:59] and current balance $[18:61]

4. Verify Placeholder Values Are Available

Check timing:

• Before Insert: Some fields may not be populated yet

• After Delete: Record no longer exists (may not have access to fields)

• Linked tables: Ensure related record exists

Test thoroughly:

• Test with actual data

• Verify placeholders resolve correctly

• Check edge cases (empty fields, zero values, etc.)

5. Format Numbers Appropriately

Currency:

"Amount: $[36:109]"
not
"Amount: [36:109]

Percentages:

"Discount: [([36:176] / [36:109]

Quantities:

"Quantity: [37:15]

6. Avoid Overly Complex Calculations

Poor (too complex):

"Value: [(([37:22] - [27:21]) * [37:15]) / (([27:22] + [27:23]

Better (use multiple placeholders):

"Unit margin: $([37:22] - [27:21])
Line margin: $(([37:22] - [27:21]) * [37:15])
Margin percentage: [(([37:22] - [27:21]) / [37:22]

7. Test Placeholders with Real Data

Don't assume placeholders work:

• Create test transaction with known data

• Verify placeholder shows expected value

• Test with edge cases (blanks, zeros, large numbers)

• Check formatting

8. Document Placeholder Meanings

In rule description, note what placeholders represent:

Rule: Credit Limit Check
Description: Validates order + balance doesn't exceed credit limit

Placeholders used:
[18:2] - Customer Name
[18:59] - Credit Limit (LCY)
[18:61] - Balance (LCY)
[36:109] - Amount Including VAT

Formula: {[36:109] + [18:61]} is >[18:59]

9. Consistent Formatting Across Rules

Establish standard format for similar messages:

Credit-related messages always show:
"Customer [18:2] has credit limit $[18:59] and balance $[18:61]."

Discount-related messages always show:
"Discount of [DiscountPercent]% exceeds maximum authorized discount of [MaxPercent]

10. Use Placeholders in Email Subjects

Make emails identifiable at a glance:

Subject: "Order [36:3] Created: $[36:109]

Common Placeholder Patterns

Pattern 1: Credit Limit Message

"Credit limit exceeded. Customer [18:2] has credit limit $[18:59] 
but current balance $[18:61] plus this order $[36:109] would total 
$([18:61] + [36:109]), exceeding limit by $([18:61] + [36:109] - [18:59]).

Please:
- Reduce order to $([18:59] - [18:61]

Pattern 2: Discount Authorization

"Discount percentage [([36:176] / [36:109]) * 100]% exceeds maximum authorized 
discount of 15% for salesperson [36:43]. 

Discount amount: $[36:176]
Order amount: $[36:109]

Please obtain manager approval or reduce discount to $([36:109]

Pattern 3: Inventory Warning

"Low inventory alert: Item [27:3] (Item No. [27:1]) has only [27:18] units 
in stock, but this order requests [37:15] units.

This will create a backorder of ([37:15] - [27:18]) units.
Estimated fulfillment date: [EstimatedDate]

Pattern 4: Price Below Cost

"Price warning: Unit price $[37:22] is below unit cost $[27:21] for item [27:3].

Loss per unit: $([27:21] - [37:22])
Total line loss: $(([27:21] - [37:22]) * [37:15]

Pattern 5: Large Order Notification

Email Subject: "Large Order Alert: $[36:109]"

Email Body:
"A large order was created requiring your review:

Order No.: [36:3]
Customer: [18:2] ([18:1])
Amount: $[36:109]
Created By: [USERID]
Date: [36:99]

This order exceeds the typical order size of $[18:73] for this customer 
by $([36:109] - [18:73]

Pattern 6: Customer Blocked

"Cannot process transaction. Customer [18:2] ([18:1]) is blocked for [18:40].

Current Status: [18:39]
Block Reason: [18:40]

Conclusion

Placeholders transform business rules from rigid, generic validations into intelligent, context-aware communications that empower users to understand and resolve issues independently.

Key principles:

Always use placeholders to:

• Show specific data values

• Explain exactly what's wrong

• Provide actionable resolution steps

• Reduce support burden

Master the syntax:

• [TableNumber:FieldNumber]

• No spaces inside brackets

• Use calculations: ([36:109] + [18:61])

• Verify table/field numbers

Design effective messages:

• Explain the problem clearly

• Show relevant data with placeholders

• Provide specific resolution steps

• Include contact information if needed

Test thoroughly:

• Verify placeholders resolve correctly

• Test with real data

• Check edge cases

• Validate calculations

Optimize for users:

• Use clear, non-technical language

• Format numbers appropriately (currency, percentages)

• Structure messages logically

• Be concise but comprehensive

By mastering placeholders, you transform error messages from frustrating roadblocks into helpful guides that enable users to solve problems efficiently and maintain productivity—creating business rules that users actually appreciate rather than merely tolerate.

Quick Reference: Common Business Central Tables

Related Reading:

• Scenarios vs. Conditions: Mastering the Two-Tier Validation Model

• Writing Effective Error Messages: User Experience Best Practices

• Advanced Formula Techniques: Complex Business Logic Made Simple

• Email Actions: Automated Notifications and Workflows