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Has Prefix

Checks if a string starts with a specified prefix, returning true or false.

Common Properties​

  • Name - The custom name of the node.
  • Color - The custom color of the node.
  • Delay Before (sec) - Waits in seconds before executing the node.
  • Delay After (sec) - Waits in seconds after executing node.
  • Continue On Error - Automation will continue regardless of any error. The default value is false.
info

If the ContinueOnError property is true, no error is caught when the project is executed, even if a Catch node is used.

Inputs​

  • String - The string to check.
  • Prefix - The prefix to look for at the beginning of the string.

Options​

This node does not have configurable options.

Output​

  • Result - Boolean value: true if string starts with prefix, false otherwise.

How It Works​

The Has Prefix node checks if a string begins with the specified prefix:

  • Case-sensitive: "Hello" and "hello" are different
  • Exact match: Prefix must match exactly from the start
  • Returns boolean: true if starts with prefix, false otherwise
  • Empty prefix: Always returns true

Usage Examples​

Example 1: Check URL Protocol​

  • String: "https://example.com"
  • Prefix: "https://"
  • Result: true

Example 2: Validate Phone Number Format​

  • String: "+1-555-1234"
  • Prefix: "+1"
  • Result: true

Example 3: Check File Path​

  • String: "/home/user/documents"
  • Prefix: "/home"
  • Result: true

Example 4: Case Sensitivity​

  • String: "Hello World"
  • Prefix: "hello"
  • Result: false (lowercase 'h')

Example 5: Prefix Not Matching​

  • String: "Hello World"
  • Prefix: "Goodbye"
  • Result: false

Tips​

  • Use for protocol validation (http://, https://, ftp://)
  • Great for path validation (check if starts with /home, C:, etc.)
  • Useful for format validation (phone numbers, IDs, codes)
  • Search is case-sensitive - use Lowercase node first for case-insensitive check
  • More specific than Includes - only checks the beginning
  • Use with If node for conditional routing

Common Errors and Solutions​

Error: Returns false when prefix should match

  • Cause: Case sensitivity mismatch
  • Solution: Convert both to same case before checking: 
    1. Lowercase both string and prefix
    2. Then use HasPrefix

Error: Extra spaces causing mismatch

  • Cause: Leading whitespace in string
  • Solution: Use Trim node first to remove leading whitespace

Practical RPA Examples​

Example: Validate URL Protocol​

String: ${msg.url}
Prefix: "https://"
Result: true/false
Action: If false, prepend "https://"

Example: Filter Files by Directory​

String: ${msg.filePath}
Prefix: "/var/log/"
Result: true
Action: Process only log files

Example: Validate Customer ID Format​

String: ${msg.customerId}
Prefix: "CUST-"
Result: true/false
Action: If false, show format error

Example: Check Email Domain​

String: ${msg.email}
Prefix: "admin@"
Result: true
Action: Route to admin queue

Example: Identify Product Category​

String: ${msg.productCode}
Prefix: "ELEC-"
Result: true
Action: Electronics category

Example: Detect System Path​

String: ${msg.path}
Prefix: "C:\\"
Result: true
Action: Windows system path detected

Pattern: Multi-Condition Routing​

Route based on different prefixes:

Check 1: HasPrefix "ERROR-" → Route to error handler
Check 2: HasPrefix "WARN-" → Route to warning handler
Check 3: HasPrefix "INFO-" → Route to info handler

Pattern: Protocol Normalization​

Ensure URLs have protocol:

Step 1: HasPrefix "http://" or "https://"
Step 2: If false, prepend "https://"
Result: Normalized URL with protocol

Pattern: Path Validation​

Validate file paths:

Linux: HasPrefix "/"
Windows: HasPrefix "C:\\" or "D:\\"
Network: HasPrefix "\\\\"

Case-Insensitive Prefix Check​

For case-insensitive matching:

Step 1: Lowercase on input string
Step 2: Lowercase on prefix
Step 3: HasPrefix check
Result: Case-insensitive prefix match

Combining with HasSuffix​

Check both start and end:

Example: Validate email format
1. HasPrefix - should not start with "@"
2. HasSuffix - should end with ".com"
Both checks must pass
  • HasSuffix - Check if ends with suffix
  • Includes - Check if contains substring
    • Get position (prefix check: index == 0)
  • Lowercase - For case-insensitive checks
  • Trim - Remove leading whitespace before check