query

Documentation

Overview

Package query provides a parser for the right-hand side query part of the bloblang spec. This is useful as a separate package as it is used in isolation within interpolation functions.

Index

• Variables
• func ExecToBytes(fn Function, ctx FunctionContext) []byte
• func ExecToString(fn Function, ctx FunctionContext) string
• func IClone(root interface{}) interface{}
• func IGetBool(v interface{}) (bool, error)
• func IGetInt(v interface{}) (int64, error)
• func IGetNumber(v interface{}) (float64, error)
• func IGetString(v interface{}) (string, error)
• func IIsNull(i interface{}) bool
• func ISanitize(i interface{}) interface{}
• func IToBool(v interface{}) (bool, error)
• func IToBytes(i interface{}) []byte
• func IToNumber(v interface{}) (float64, error)
• func IToString(i interface{}) string
• func ListFunctions() []string
• func ListMethods() []string
• func Parse(input []rune) parser.Result
• func ParseDeprecated(input []rune) parser.Result
• func RegisterFunction(name string, allowDynamicArgs bool, ctor FunctionCtor, checks ...ArgCheckFn) struct{}
• func RegisterMethod(name string, allowDynamicArgs bool, ctor MethodCtor, checks ...ArgCheckFn) struct{}
• type ArgCheckFn
  • func ExpectAllStringArgs() ArgCheckFn
  • func ExpectAtLeastOneArg() ArgCheckFn
  • func ExpectBoolArg(i int) ArgCheckFn
  • func ExpectFloatArg(i int) ArgCheckFn
  • func ExpectIntArg(i int) ArgCheckFn
  • func ExpectNArgs(i int) ArgCheckFn
  • func ExpectOneOrZeroArgs() ArgCheckFn
  • func ExpectStringArg(i int) ArgCheckFn
• type Delete
• type ErrRecoverable
  • func (e *ErrRecoverable) Error() string
• type Function
  • func New(query string) (Function, error)
• type FunctionContext
• type FunctionCtor
• type MessageBatch
• type MethodCtor
• type Nothing
• type TypeError
  • func NewTypeError(actual interface{}, exp ...ValueType) *TypeError
  • func (t *TypeError) Error() string
• type TypeMismatch
  • func NewTypeMismatch(left, right interface{}) *TypeMismatch
  • func (t *TypeMismatch) Error() string
• type ValueType
  • func ITypeOf(i interface{}) ValueType

Variables

var ErrDivideByZero = errors.New("attempted to divide by zero")

ErrDivideByZero occurs when an arithmetic operator is prevented from dividing a value by zero.

Functions

func ExecToBytes

func ExecToBytes(fn Function, ctx FunctionContext) []byte

ExecToBytes returns a byte slice from a function exection.

func ExecToString

func ExecToString(fn Function, ctx FunctionContext) string

ExecToString returns a string from a function exection.

func IClone

func IClone(root interface{}) interface{}

IClone performs a deep copy of a generic value.

func IGetBool

func IGetBool(v interface{}) (bool, error)

IGetBool takes a boxed value and attempts to extract a boolean from it.

func IGetInt

func IGetInt(v interface{}) (int64, error)

IGetInt takes a boxed value and attempts to extract an integer (int64) from it.

func IGetNumber

func IGetNumber(v interface{}) (float64, error)

IGetNumber takes a boxed value and attempts to extract a number (float64) from it.

func IGetString

func IGetString(v interface{}) (string, error)

IGetString takes a boxed value and attempts to return a string value. Returns an error if the value is not a string or byte slice.

func IIsNull

func IIsNull(i interface{}) bool

IIsNull returns whether a bloblang type is null, this includes Delete and Nothing types.

func ISanitize

func ISanitize(i interface{}) interface{}

ISanitize takes a boxed value of any type and attempts to convert it into one of the following types: string, []byte, int64, uint64, float64, bool, []interface{}, map[string]interface{}, Delete, Nothing.

func IToBool

func IToBool(v interface{}) (bool, error)

IToBool takes a boxed value and attempts to extract a boolean from it or parse it into a bool.

func IToBytes

func IToBytes(i interface{}) []byte

IToBytes takes a boxed value of any type and attempts to convert it into a byte slice.

func IToNumber

func IToNumber(v interface{}) (float64, error)

IToNumber takes a boxed value and attempts to extract a number (float64) from it or parse one.

func IToString

func IToString(i interface{}) string

IToString takes a boxed value of any type and attempts to convert it into a string.

func ListFunctions

func ListFunctions() []string

ListFunctions returns a slice of function names, sorted alphabetically.

func ListMethods

func ListMethods() []string

ListMethods returns a slice of method names, sorted alphabetically.

func Parse

func Parse(input []rune) parser.Result

Parse parses an input into a query.Function.

func ParseDeprecated

func ParseDeprecated(input []rune) parser.Result

ParseDeprecated parses an input into a query.Function, but permits deprecated function interpolations. In order to support old functions this parser does not include field literals.

func RegisterFunction

func RegisterFunction(name string, allowDynamicArgs bool, ctor FunctionCtor, checks ...ArgCheckFn) struct{}

RegisterFunction to be accessible from Bloblang queries. Returns an empty struct in order to allow inline calls.

func RegisterMethod

func RegisterMethod(name string, allowDynamicArgs bool, ctor MethodCtor, checks ...ArgCheckFn) struct{}

RegisterMethod to be accessible from Bloblang queries. Returns an empty struct in order to allow inline calls.

Types

type ArgCheckFn

type ArgCheckFn func(args []interface{}) error

ArgCheckFn is an optional argument type checker for a function constructor.

func ExpectAllStringArgs

func ExpectAllStringArgs() ArgCheckFn

ExpectAllStringArgs returns an error if any argument is not a string type (or a byte slice that can be converted).

func ExpectAtLeastOneArg

func ExpectAtLeastOneArg() ArgCheckFn

ExpectAtLeastOneArg returns an error unless >0 arguments are specified.

func ExpectBoolArg

func ExpectBoolArg(i int) ArgCheckFn

ExpectBoolArg returns an error if an argument i is not a boolean type.

func ExpectFloatArg

func ExpectFloatArg(i int) ArgCheckFn

ExpectFloatArg returns an error if an argument i is not a float type.

func ExpectIntArg

func ExpectIntArg(i int) ArgCheckFn

ExpectIntArg returns an error if an argument i is not an integer type.

func ExpectNArgs

func ExpectNArgs(i int) ArgCheckFn

ExpectNArgs returns an error unless exactly N arguments are specified.

func ExpectOneOrZeroArgs

func ExpectOneOrZeroArgs() ArgCheckFn

ExpectOneOrZeroArgs returns an error if more than one arg is specified.

func ExpectStringArg

func ExpectStringArg(i int) ArgCheckFn

ExpectStringArg returns an error if an argument i is not a string type (or a byte slice that can be converted).

type Delete

type Delete *struct{}

Delete is a special type that serializes to `null` when forced but indicates a target should be deleted.

type ErrRecoverable

type ErrRecoverable struct {
	Recovered interface{}
	Err       error
}

ErrRecoverable represents a function execution error that can optionally be recovered into a zero-value.

func (*ErrRecoverable) Error

func (e *ErrRecoverable) Error() string

Error implements the standard error interface.

type Function

type Function interface {
	// Execute this function for a message of a batch.
	Exec(ctx FunctionContext) (interface{}, error)
}

Function takes a set of contextual parameters and returns the result of the query.

func New

func New(query string) (Function, error)

New creates a new query function from a query string.

type FunctionContext

type FunctionContext struct {
	Value    *interface{}
	Maps     map[string]Function
	Vars     map[string]interface{}
	Index    int
	MsgBatch MessageBatch
	Legacy   bool
}

FunctionContext provides access to a root message, its index within the batch, and

type FunctionCtor

type FunctionCtor func(args ...interface{}) (Function, error)

FunctionCtor constructs a new function from input arguments.

type MessageBatch

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

MessageBatch is an interface type to be given to a query function, it allows the function to resolve fields and metadata from a Benthos message batch.

type MethodCtor

type MethodCtor func(target Function, args ...interface{}) (Function, error)

MethodCtor constructs a new method from a target function and input args.

type Nothing

type Nothing *struct{}

Nothing is a special type that serializes to `null` when forced but indicates a query should be disregarded (and not mapped).

type TypeError

type TypeError struct {
	Expected []ValueType
	Actual   ValueType
	Value    interface{}
}

TypeError represents an error where a value of a type was required for a function, method or operator but instead a different type was found.

func NewTypeError

func NewTypeError(actual interface{}, exp ...ValueType) *TypeError

NewTypeError creates a new type error.

func (*TypeError) Error

func (t *TypeError) Error() string

Error implements the standard error interface for TypeError.

type TypeMismatch

type TypeMismatch struct {
	Left  ValueType
	Right ValueType
}

TypeMismatch represents an error where two values should be a comparable type but are not.

func NewTypeMismatch

func NewTypeMismatch(left, right interface{}) *TypeMismatch

NewTypeMismatch creates a new type mismatch error.

func (*TypeMismatch) Error

func (t *TypeMismatch) Error() string

Error implements the standard error interface.

type ValueType

type ValueType string

ValueType represents a discrete value type supported by Bloblang queries.

var (
	ValueString  ValueType = "string"
	ValueBytes   ValueType = "bytes"
	ValueNumber  ValueType = "number"
	ValueBool    ValueType = "bool"
	ValueArray   ValueType = "array"
	ValueObject  ValueType = "object"
	ValueNull    ValueType = "null"
	ValueDelete  ValueType = "delete"
	ValueNothing ValueType = "nothing"
	ValueUnknown ValueType = "unknown"
)

ValueType variants.

func ITypeOf

func ITypeOf(i interface{}) ValueType

ITypeOf returns the type of a boxed value as a discrete ValueType. If the type of the value is unknown then ValueUnknown is returned.