daq

package module
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 Go to latest Published: Jan 2, 2024 License: MIT Imports: 4 Imported by: 7

README

daq

DAta Queries: Access nested properties in Go data structures.

Go Reference

Documentation

Overview

Access nested properties in Go data structures with DAta Queries

Example 
var data any
json.Unmarshal([]byte(`{
		"a": 3.1415,
		"bs": [1, 2, 3]
	}`), &data)

prop, _ := Get(data, "a") // Ignore error in example for brevity
fmt.Println(prop)

prop, err := Get(data, "b") // This will fail, no "b"
fmt.Println(prop, err)

x, err := AsFloat64(Get(data, "bs", 1)) // Type assertion (encoding/json uses float64 for numbers)
fmt.Println(x, err)

x, err = AsFloat64(Get(data, "bs", -1)) // Access backwards from end
fmt.Println(x, err)

x = Float64Or(-1)(Get(data, "bs", 3)) // Fallback to -1 if Get has error
fmt.Println(x)

Output:

3.1415
<nil> step 0 [b]: no field named 'b'
2 <nil>
3 <nil>
-1

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func AsBool 

func AsBool(v any, err error) (bool, error)
Example 
fmt.Println(AsBool(Get(true)))
fmt.Println(Val(AsBool, false)(Get(4711)))

Output:

true <nil>
false

func AsDuration 

func AsDuration(v any, err error) (time.Duration, error)

func AsFloat32 

func AsFloat32(v any, err error) (float32, error)

func AsFloat64 

func AsFloat64(v any, err error) (float64, error)

func AsInt 

func AsInt(v any, err error) (int, error)

func AsInt16 

func AsInt16(v any, err error) (int16, error)

func AsInt32 

func AsInt32(v any, err error) (int32, error)

func AsInt64 

func AsInt64(v any, err error) (int64, error)

func AsInt8 

func AsInt8(v any, err error) (int8, error)

func AsString 

func AsString(v any, err error) (string, error)
Example 
fmt.Println(Val(AsString, "-")(Map(testExample).Get("a")))
fmt.Println(Val(AsString, "-")(Get(testExample, "a", 0, "d")))

Output:

-
foo

func AsTime 

func AsTime(v any, err error) (time.Time, error)

func AsUint 

func AsUint(v any, err error) (uint, error)

func AsUint16 

func AsUint16(v any, err error) (uint16, error)

func AsUint32 

func AsUint32(v any, err error) (uint32, error)

func AsUint64 

func AsUint64(v any, err error) (uint64, error)

func AsUint8 

func AsUint8(v any, err error) (uint8, error)

func AsUintPtr 

func AsUintPtr(v any, err error) (uintptr, error)

func BoolOr 

func BoolOr(fallback bool) func(any, error) bool

func DurationOr 

func DurationOr(fallback time.Duration) func(any, error) time.Duration

func Field 

func Field(data any, name string) (any, error)

func Float32Or 

func Float32Or(fallback float32) func(any, error) float32

func Float64Or 

func Float64Or(fallback float64) func(any, error) float64

func Get 

func Get(data any, path ...any) (res any, err error)

func Index 

func Index(data any, i int) (any, error)

func Int16Or 

func Int16Or(fallback int16) func(any, error) int16

func Int32Or 

func Int32Or(fallback int32) func(any, error) int32

func Int64Or 

func Int64Or(fallback int64) func(any, error) int64

func Int8Or 

func Int8Or(fallback int8) func(any, error) int8

func IntOr 

func IntOr(fallback int) func(any, error) int

func MapOr 

func MapOr(fallback Map) func(any, error) Map

func SliceOr 

func SliceOr(fallback Slice) func(any, error) Slice

func Step 

func Step(data, step any) (any, error)

func StepEach added in v0.3.0 

func StepEach(data any, do func(key, value any) error) error
Example (Array) 
data := [4]any{0, '1', "two", nil}
err := StepEach(data, testStepEach)
fmt.Println(err)

Output:

k=0 / v=0
k=1 / v=49
k=2 / v="two"
k=3 / v=<nil>
<nil>
Example (Atom) 
err := StepEach(5180, testStepEach)
fmt.Println(err)

Output:

<nil>
Example (Map) 
data := map[any]any{
	false: "foo",
	7:     nil,
	"bar": 4711,
}
err := StepEach(data, testStepEach)
fmt.Println(err)

Output:

k=false / v="foo"
k=7 / v=<nil>
k="bar" / v=4711
<nil>
Example (Slice) 
data := []any{0, '1', "two", nil}
err := StepEach(data, testStepEach)
fmt.Println(err)

Output:

k=0 / v=0
k=1 / v=49
k=2 / v="two"
k=3 / v=<nil>
<nil>
Example (Struct) 
type Tstnest struct {
	Foo int
}
data := struct {
	Tstnest
	Bar  string
	Nest Tstnest
}{
	Tstnest: Tstnest{Foo: 4711},
	Bar:     "baz",
	Nest:    Tstnest{Foo: -1},
}
err := StepEach(data, testStepEach)
fmt.Println(err)

Output:

k="Foo" / v=4711
k="Bar" / v="baz"
k="Nest" / v=daq.Tstnest{Foo:-1}
<nil>

func StringOr 

func StringOr(fallback string) func(any, error) string

func TimeOr 

func TimeOr(fallback time.Time) func(any, error) time.Time

func Uint16Or 

func Uint16Or(fallback uint16) func(any, error) uint16

func Uint32Or 

func Uint32Or(fallback uint32) func(any, error) uint32

func Uint64Or 

func Uint64Or(fallback uint64) func(any, error) uint64

func Uint8Or 

func Uint8Or(fallback uint8) func(any, error) uint8

func UintOr 

func UintOr(fallback uint) func(any, error) uint

func UintPtrOr 

func UintPtrOr(fallback uintptr) func(any, error) uintptr

func Val 

func Val[T any](assert func(any, error) (T, error), fallback T) func(v any, err error) T
Example 
data := struct {
	Foo int
	Bar string
}{
	Foo: 4711,
	Bar: "baz",
}
fmt.Println(Val(AsString, "fallback1")(Get(data, "Foo")))
fmt.Println(Val(AsString, "fallback2")(Get(data, "Bar")))
fmt.Println(Val(AsString, "fallback3")(Get(data, "void")))

Output:

fallback1
baz
fallback3

Types

type Alt 

type Alt struct {
	S        any
	Fallback any
}

func (Alt) Step 

func (a Alt) Step(data any) (any, error)

type FirstNameOf 

type FirstNameOf []string

func (FirstNameOf) Step 

func (ns FirstNameOf) Step(data any) (res any, err error)

type FirstOf 

type FirstOf []any

func (FirstOf) Step 

func (keys FirstOf) Step(data any) (res any, err error)

type Map 

type Map map[string]any

func AsMap 

func AsMap(v any, err error) (Map, error)

func (Map) Get 

func (m Map) Get(n string) (any, error)

type NoValue 

type NoValue struct {
	ForStep any
}

func (NoValue) Error 

func (e NoValue) Error() string

type Slice 

type Slice []any

func AsSlice 

func AsSlice(v any, err error) (Slice, error)
Example 
for _, e := range Val(AsSlice, nil)(testExample.Get("a")) {
	fmt.Println(e)
}

Output:

map[b:map[c:3] d:foo]
false

func (Slice) Get 

func (s Slice) Get(i int) (any, error)

type StepError 

type StepError struct {
	N    int
	Step any
	Err  error
}

func (StepError) Error 

func (e StepError) Error() string

func (StepError) Unwrap 

func (e StepError) Unwrap() error

type Stepper 

type Stepper interface {
	Step(data any) (any, error)
}

type Time 

type Time string
Example 
data := struct {
	Time string
}{
	Time: "2023-12-29T22:04:00Z",
}
fmt.Println(Val(Time(time.RFC3339).As, time.Time{})(Get(data, "Time")))
fmt.Println(Val(Time(time.RFC3339).As, time.Time{})(Get(data, "void")))

Output:

2023-12-29 22:04:00 +0000 UTC
0001-01-01 00:00:00 +0000 UTC

func (Time) As 

func (t Time) As(v any, err error) (time.Time, error)

type Track 

type Track []any

func GetTrack 

func GetTrack(data any, path ...any) (t Track, err error)

func (Track) At 

func (t Track) At(i int) any

Source Files

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