bml-pitfalls

BML Pitfalls & Anti-Patterns

1. Syntax & Keywords

• Do NOT use var, let, or const: BML has no variable declaration keywords. Direct assignment only: myVar = "value";.
• Do NOT use C-style logical operators &&, ||, or !: Strictly use BML keywords AND, OR, and NOT(condition).
• Use == and <>, NOT === and !=: In BML, <> is the canonical not-equal operator.
• Always terminate statements with ;: Every BML statement must end with a semicolon.
• Single statement per line: Avoid placing multiple statements on the same line.

2. Nesting & Performance

• Loop Nesting Limit (Max 3): Loop nesting depth must not exceed 3 (warning at depth 4+). Flatten loops using Maps/Dictionaries or helper functions.
• Block & Condition Nesting Limit (Max 5): Condition/block nesting depth must not exceed 5 (warning at depth 6+).
• Avoid Repeated BMQL inside loops: Fetch bulk data into a RecordSet or Dictionary outside loops to avoid N+1 query overhead.

3. Data Types & Comparisons

• NULL vs Blank String:
  • NULL for integers/numbers evaluates to 0.
  • Blank string evaluates to "".
  • NULL and blank strings are treated as separate values in CPQ. Confirm comparison logic accounts for this difference.
• Array Size Limits:
  • Default BML row size limit is 5000; default column size limit is 50.
• Dictionary Value Constraints:
  • Legacy typed dictionaries (e.g. dict("string")) cannot hold nested dictionaries. Use dict("anytype") or JSON objects (json(), jsonarray()) for nested structures.

4. Security & BMQL

• SQL Injection Prevention: Never concatenate raw input parameters directly into BMQL query strings. Always use dynamic BMQL $variable substitution.
• BMQL Cap Limit: Statements using UPDATE, MODIFY, DISTINCT, or ORDER BY process or return a maximum of 1,000 records.