stringx

Documentation

Overview

Package strings String expressions, with the exception of $concat, only have a well-defined behavior for strings of ASCII characters.

Index

• func Concat[T expression.StrExpression](ns []T) stringOperator
• func IndexOfBytes[T expression.StrExpression, N expression.IntExpression](str, sub T, start, end N) stringOperator
• func IndexOfCP[T expression.StrExpression, N expression.IntExpression](str, sub T, start, end N) stringOperator
• func Ltrim[T expression.StrExpression](input, chars T) stringOperator
• func RegexFind[T expression.StrExpression](input, regex T, options string) stringOperator
• func RegexFindAll[T expression.StrExpression](input, regex T, options string) stringOperator
• func RegexMatch[T expression.StrExpression](input, regex T, options string) stringOperator
• func ReplaceAll[T expression.StrExpression](input, find, replacement T) stringOperator
• func ReplaceOne[T expression.StrExpression](input, find, replacement T) stringOperator
• func Rtrim[T expression.StrExpression](input, chars T) stringOperator
• func Split[T expression.StrExpression](str, delimiter T) stringOperator
• func StrCaseCmp[T expression.StrExpression](e1, e2 T) stringOperator
• func StrLenBytes[T expression.StrExpression](str T) stringOperator
• func StrLenCP[T expression.StrExpression](str T) stringOperator
• func Substr[T expression.StrExpression, N expression.IntExpression](str T, start, length N) stringOperator
• func SubstrBytes[T expression.StrExpression, N expression.NumberExpression](str T, index, count N) stringOperator
• func SubstrCP[T expression.StrExpression, N expression.NumberExpression](str T, index, count N) stringOperator
• func ToLower[T expression.StrExpression](str T) stringOperator
• func ToString[T expression.AnyExpression](str T) stringOperator
• func ToUpper[T expression.StrExpression](str T) stringOperator
• func Trim[T expression.StrExpression](input, chars T) stringOperator

Functions

func Concat

func Concat[T expression.StrExpression](ns []T) stringOperator

Concat Concatenates strings and returns the concatenated string. $concat has the following syntax: { $concat: [ <expression1>, <expression2>, ... ] } The arguments can be any valid expression as long as they resolve to strings. For more information on expressions, see Expressions. If the argument resolves to a value of null or refers to a field that is missing, $concat returns null.

func IndexOfBytes

func IndexOfBytes[T expression.StrExpression, N expression.IntExpression](str, sub T, start, end N) stringOperator

IndexOfBytes Searches a string for an occurrence of a substring and returns the UTF-8 byte index (zero-based) of the first occurrence. If the substring is not found, returns -1. $indexOfBytes has the following operator expression syntax: { $indexOfBytes: [ <string expression>, <substring expression>, <start>, <end> ] }

func IndexOfCP

func IndexOfCP[T expression.StrExpression, N expression.IntExpression](str, sub T, start, end N) stringOperator

IndexOfCP Searches a string for an occurrence of a substring and returns the UTF-8 code point index (zero-based) of the first occurrence. If the substring is not found, returns -1. $indexOfCP has the following operator expression syntax: { $indexOfCP: [ <string expression>, <substring expression>, <start>, <end> ] }

func Ltrim

func Ltrim[T expression.StrExpression](input, chars T) stringOperator

Ltrim Removes whitespace characters, including null, or the specified characters from the beginning of a string. $ltrim has the following syntax: { $ltrim: { input: <string>, chars: <string> } }

func RegexFind

func RegexFind[T expression.StrExpression](input, regex T, options string) stringOperator

RegexFind New in version 4.2. Provides regular expression (regex) pattern matching capability in aggregation expressions. If a match is found, returns a document that contains information on the first match. If a match is not found, returns null. MongoDB uses Perl compatible regular expressions (i.e. "PCRE" ) version 8.41 with UTF-8 support. Prior to MongoDB 4.2, aggregation pipeline can only use the query operator $regex in the $match stage. For more information on using regex in a query, see $regex.

func RegexFindAll

func RegexFindAll[T expression.StrExpression](input, regex T, options string) stringOperator

RegexFindAll New in version 4.2. Provides regular expression (regex) pattern matching capability in aggregation expressions. The operator returns an array of documents that contains information on each match. If a match is not found, returns an empty array. MongoDB uses Perl compatible regular expressions (i.e. "PCRE" ) version 8.41 with UTF-8 support. Prior to MongoDB 4.2, aggregation pipeline can only use the query operator $regex in the $match stage. For more information on using regex in a query, see $regex.

func RegexMatch

func RegexMatch[T expression.StrExpression](input, regex T, options string) stringOperator

RegexMatch New in version 4.2. Performs a regular expression (regex) pattern matching and returns: true if a match exists. false if a match doesn't exist. MongoDB uses Perl compatible regular expressions (i.e. "PCRE" ) version 8.41 with UTF-8 support. Prior to MongoDB 4.2, aggregation pipeline can only use the query operator $regex in the $match stage. For more information on using regex in a query, see $regex.

func ReplaceAll

func ReplaceAll[T expression.StrExpression](input, find, replacement T) stringOperator

ReplaceAll New in version 4.4. Replaces all instances of a search string in an input string with a replacement string. $replaceAll is both case-sensitive and diacritic-sensitive, and ignores any collation present on a collection. The $replaceAll operator has the following operator expression syntax: { $replaceAll: { input: <expression>, find: <expression>, replacement: <expression> } }

func ReplaceOne

func ReplaceOne[T expression.StrExpression](input, find, replacement T) stringOperator

ReplaceOne New in version 4.4. Replaces the first instance of a search string in an input string with a replacement string. If no occurrences are found, $replaceOne evaluates to the input string. $replaceOne is both case-sensitive and diacritic-sensitive, and ignores any collation present on a collection. The $replaceOne operator has the following operator expression syntax: { $replaceOne: { input: <expression>, find: <expression>, replacement: <expression> } }

func Rtrim

func Rtrim[T expression.StrExpression](input, chars T) stringOperator

Rtrim Removes whitespace characters, including null, or the specified characters from the end of a string. $rtrim has the following syntax: { $rtrim: { input: <string>, chars: <string> } }

func Split

func Split[T expression.StrExpression](str, delimiter T) stringOperator

Split Divides a string into an array of substrings based on a delimiter. $split removes the delimiter and returns the resulting substrings as elements of an array. If the delimiter is not found in the string, $split returns the original string as the only element of an array. $split has the following operator expression syntax: { $split: [ <string expression>, <delimiter> ] }

func StrCaseCmp

func StrCaseCmp[T expression.StrExpression](e1, e2 T) stringOperator

StrCaseCmp Performs case-insensitive comparison of two strings. Returns 1 if first string is "greater than" the second string. 0 if the two strings are equal. -1 if the first string is "less than" the second string. $strcasecmp has the following syntax: { $strcasecmp: [ <expression1>, <expression2> ] } The arguments can be any valid expression as long as they resolve to strings.

func StrLenBytes

func StrLenBytes[T expression.StrExpression](str T) stringOperator

StrLenBytes Returns the number of UTF-8 encoded bytes in the specified string. $strLenBytes has the following operator expression syntax: { $strLenBytes: <string expression> } The argument can be any valid expression as long as it resolves to a string. For more information on expressions, see Expressions. If the argument resolves to a value of null or refers to a missing field, $strLenBytes returns an error.

func StrLenCP

func StrLenCP[T expression.StrExpression](str T) stringOperator

StrLenCP Returns the number of UTF-8 code points in the specified string. $strLenCP has the following operator expression syntax: { $strLenCP: <string expression> } The argument can be any valid expression that resolves to a string. If the argument resolves to a value of null or refers to a missing field, $strLenCP returns an error.

func Substr

func Substr[T expression.StrExpression, N expression.IntExpression](str T, start, length N) stringOperator

Substr Deprecated since version 3.4: $substr is now an alias for $substrBytes. Returns a substring of a string, starting at a specified index position and including the specified number of characters. The index is zero-based. $substr has the following syntax: { $substr: [ <string>, <start>, <length> ] } The arguments can be any valid expression as long as the first argument resolves to a string, and the second and third arguments resolve to integers

func SubstrBytes

func SubstrBytes[T expression.StrExpression, N expression.NumberExpression](str T, index, count N) stringOperator

SubstrBytes Returns the substring of a string. The substring starts with the character at the specified UTF-8 byte index (zero-based) in the string and continues for the number of bytes specified. $substrBytes has the following operator expression syntax: { $substrBytes: [ <string expression>, <byte index>, <byte count> ] }

func SubstrCP

func SubstrCP[T expression.StrExpression, N expression.NumberExpression](str T, index, count N) stringOperator

SubstrCP SubstrCPReturns the substring of a string. The substring starts with the character at the specified UTF-8 code point (CP) index (zero-based) in the string for the number of code points specified. $substrCP has the following operator expression syntax: { $substrCP: [ <string expression>, <code point index>, <code point count> ]

func ToLower

func ToLower[T expression.StrExpression](str T) stringOperator

ToLower Converts a string to lowercase, returning the result. $toLower has the following syntax: { $toLower: <expression> } The argument can be any expression as long as it resolves to a string.

func ToString

func ToString[T expression.AnyExpression](str T) stringOperator

ToString Converts a value to a string. If the value cannot be converted to a string, $toString errors. If the value is null or missing, $toString returns null. $toString has the following syntax:

{
  $toString: <expression>
}

The $toString takes any valid expression. The $toString is a shorthand for the following $convert expression: { $convert: { input: <expression>, to: "string" } }

func ToUpper

func ToUpper[T expression.StrExpression](str T) stringOperator

ToUpper Converts a string to uppercase, returning the result. $toUpper has the following syntax: { $toUpper: <expression> } The argument can be any expression as long as it resolves to a string

func Trim

func Trim[T expression.StrExpression](input, chars T) stringOperator

Trim Removes whitespace characters, including null, or the specified characters from the beginning and end of a string. $trim has the following syntax: { $trim: { input: <string>, chars: <string> } }