field

Documentation

Overview

Package field implements a bloblang interpolation function templating syntax used in some dynamic fields within Benthos. Only the query (right-hand side) part of the bloblang spec is supported within interpolation functions.

Index

• type Expression
  • func New(expr string) (Expression, error)
• type Message

Types

type Expression

type Expression interface {
	// Bytes returns a byte slice representing the expression resolved for a
	// message
	// of a batch.
	Bytes(index int, msg Message) []byte

	// BytesLegacy is DEPRECATED - Instructs deprecated functions to disregard
	// index information.
	// TODO V4: Remove this.
	BytesLegacy(index int, msg Message) []byte

	// BytesEscaped returns a byte slice representing the expression resolved
	// for a message of a batch with the contents of resolved expressions
	// escaped.
	BytesEscaped(index int, msg Message) []byte

	// BytesEscapedLegacy is DEPRECATED - Instructs deprecated functions to
	// disregard index information.
	// TODO V4: Remove this.
	BytesEscapedLegacy(index int, msg Message) []byte

	// String returns a string representing the expression resolved for a
	// message of a batch.
	String(index int, msg Message) string

	// StringLegacy is DEPRECATED - Instructs deprecated functions to disregard
	// index information.
	// TODO V4: Remove this.
	StringLegacy(index int, msg Message) string
}

Expression represents a Benthos dynamic field expression, used to configure string fields where the contents should change based on the contents of messages and other factors.

Each function here resolves the expression for a particular message of a batch, this is why an index is expected.

func New

func New(expr string) (Expression, error)

New attempts to parse and create an expression from a string. If the expression is invalid an error is returned.

type Message

type Message interface {
	Get(p int) types.Part
	Len() int
}

Message is an interface type to be given to a function interpolator, it allows the function to resolve fields and metadata from a message.