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This page is for anyone writing expressions, macros or scripts in which you need to escape special characters.

When writing expressions, macros or scripts you may need to enter a character that has special meaning. For example, a string could include a double-quote, but in the expression PhixFlow will read this as the end of the string. To tell PhixFlow to ignore a special character, you can use the backslash character.  

CharacterTypeEscape string

backspace

Represented As "\b"
Escaped "\\\\b"
form feedRepresented As "\f"
Escaped"\\\\f"
tabRepresented As"\t"
Escaped "\\\\t"
carraige returnRepresented As"\r"
Escaped "\\\\r"
newlineRepresented As"\n"
Escaped "\\\\n"
backslashRepresented As

"\\\\"

Escaped "\\\\\\\\"
double quoteRepresented As'"'
Escaped '\\\\"'

Macro: Escaping Invalid Characters

If you are working with JSON, return messages can contain characters that are not recognised in PhixFlow. The following macro escapes these invalid characters. 

do(
    $value = $args[1],
    $value = replaceAll( $value , "\b","\\\\b"),
    $value = replaceAll( $value , "\f","\\\\f"),
    $value = replaceAll( $value , "\t","\\\\t"),
    $value = replaceAll( $value , "\r","\\\\r"),
    $value = replaceAll( $value , "\n","\\\\n"),
    $value = replaceAll( $value , "\\\\","\\\\\\\\"),
    $value = replaceAll( $value , '"','\\\\"')
)

Validating JSON Files

JSON code can include characters that cannot be written to a database that is using the UTF-8 character set. For example, 4-bit Emojis are not supported by UTF-8.

The following regular expression lists the characters expected in a JSON file and removes invalid characters from it.

replaceAll(JSON Code,"[^\\p{Space}0-9A-Za-z!:\\\"%&\\[*()\\],-/_\\\\{}\\.]","")

The backslash character escapes special characters such as [] , . and \ 

The UTF-8mb4 character set supports a wider range of characters, such as Emojis. Migrating your database to use this character set would allow JSON to be used without needing to validate it using a regular expression.

See also: Regular Expressions



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