4. Troubleshooting

Troubleshooting

Quick Diagnostics

Symptom	Likely Cause	What To Do
{{ PropertyName }} remains in output	Unknown regular property	Check model/property spelling or add runtime parameter
Calculation renders empty	Invalid/unknown/non-numeric calculation path	Validate expression, path, and data type
Calculation renders 0	Null source/property in math path	Confirm null is expected or initialize source values
#if block not matching	Type/operator mismatch	Verify property type and comparison value
Loop renders nothing	Source is null/non-enumerable/empty	Ensure collection exists and has items

Unknown Placeholder vs Calculation Behavior

These are intentionally different:

• Regular placeholder unknown: keeps unresolved text
  • Example: {{ UnknownProp }}
• Expression unknown/invalid: renders empty
  • Example: {{ _sum(Unknown.Path) }} -> empty

Common Mistakes

1. Wrong nested path

{{ Customer.BankDetails.BankName }}

If model uses BankingDetail (singular), this expression will fail.

2. Using numeric functions on string/date

{{ _sum(Items.Name) }}
{{ _sum(OrderDate) }}

These render empty because values are not numeric.

3. Using calc with unresolved fields

{{ _calc(PaidAmount - UnknownValue) }}

This renders empty.

Performance Tips

• Reuse template strings to benefit from parser cache.
• Prefer specific property paths over deeply complex expressions.
• Keep heavy transformations outside templates when possible.
• Validate user-authored templates during save time, not only at send time.