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$ltrim

The $ltrim operator removes specified characters from the beginning (left) of a string.

📌 Syntax

{
  "$ltrim": {
    "input": <expression>,
    "chars": <charsToTrim>
  }
}

✅ Base Example 1 – Trim Leading Whitespace

📥 Input Document

{ "title": "   Notebook" }

📌 Expression

{
  "$ltrim": { "input": "$title" }
}

📤 Output

"Notebook"

✅ Base Example 2 – Trim Leading Zeros from ID

📥 Input Document

{ "id": "000123" }

📌 Expression

{
  "$ltrim": {
    "input": "$id",
    "chars": "0"
  }
}

📤 Output

"123"

🧱 Ecommerce Example – Clean Item Codes

📌 Pipeline

[
  { "$unwind": "$items" },
  {
    "$project": {
      "code": {
        "$ltrim": {
          "input": "$items.code",
          "chars": "X"
        }
      },
      "name": "$items.name"
    }
  }
]

📥 Input Document

{
  "items": [
    { "code": "XXA100", "name": "T-shirt" },
    { "code": "XXB200", "name": "Bag" }
  ]
}

📤 Output

[
  { "code": "A100", "name": "T-shirt" },
  { "code": "B200", "name": "Bag" }
]

🔧 Common Use Cases

  • Trim leading symbols, padding characters
  • Normalize document IDs or SKUs
  • Clean up data during import
  • $rtrim, $trim, $toLower, $substr

🧠 Notes

  • If chars is not specified, whitespace is removed.
  • For both sides, use $trim.