ask

package module
Version: v0.3.0 Latest Latest
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Published: Aug 21, 2022 License: MIT Imports: 5 Imported by: 2

README

ASK
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and you shall receive.

Ask provides a simple way of accessing nested properties in maps and slices. Works great in combination with encoding/json and other packages that "Unmarshal" arbitrary data into Go data-types. Inspired by the get function in the lodash javascript library.

⚠️ From version v0.3.0, the package requires Go 1.17+, due to the usage of new additions to the reflect package.

Use

package main

import "json"
import "github.com/simonnilsson/ask"

func main() {

	// Use parsed JSON as source data
	var object map[string]interface{}
	json.Unmarshal([]byte(`{ "a": [{ "b": { "c": 3 } }] }`), &object)

	// Extract the 3
	res, ok := ask.For(object, "a[0].b.c").Int(0)

	fmt.Println(res, ok)
	// Output: 3 true

	// Attempt extracting a string at path .d that does not exist
	res2, ok := ask.For(object, "a[0].b.d").String("nothing")

	fmt.Println(res2, ok)
	// Output: nothing false

}

API

Internally ask uses type assertions to traverse down the path supplied. Each invocation starts by calling For() with your data structure source and the path in this structure to extract.

For(source interface{}, path string) *Answer

Additional paths can be traversed by calling Path() on the resulting answer.

(a *Answer) Path(path string) *Answer

Type assertion

After receiving an *Answer from a call to For() it can be asserted to a type. The methods for this is seen below. Each function takes a default value as a parameter that will be returned in case the value can not be asserted from the answer. A second return value is used to indicate if the assertion was successful.

  • String(d string) (string, bool)
  • Bool(d bool) (bool, bool)
  • Int(d int64) (int64, bool)
  • Uint(d uint64) (uint64, bool)
  • Float(d float64) (float64, bool)
  • Slice(d []interface{}) ([]interface{}, bool)
  • Map(d map[string]interface{}) (map[string]interface{}, bool)

If a number is found but it is of different type than requested it will be casted to desired type and return success. If the value would not fit within the valid range of requested type the operation will fail however and the default parameter will be returned instead.

Two additional methods are available, one to check if the answer has a value (not nil) and one to return the raw value as a interface{}.

  • Exists() bool
  • Value() interface{}

For full documentation see pkg.go.dev.

License

MIT

Documentation

Overview

Package ask provides a simple way of accessing nested properties in maps and arrays. Works great in combination with encoding/json and other packages that "Unmarshal" arbitrary data into Go data-types. Inspired by the get function in the lodash javascript library.

Example
// Use parsed JSON as source data
var object map[string]interface{}
json.Unmarshal([]byte(`{
		"a": [{
			"b": {
				"c": 3
			}
		}]
 	}`), &object)

// Extract the 3
res, ok := For(object, "a[0].b.c").Int(0)
fmt.Println(res, ok)

// Attempt extracting a string at path .d that does not exist
res2, ok := For(object, "a[0].b.d").String("nothing")
fmt.Println(res2, ok)
Output:

3 true
nothing false

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Answer

type Answer struct {
	// contains filtered or unexported fields
}

Answer holds result of call to For, use one of its methods to extract a value.

func For

func For(source interface{}, path string) *Answer

For is used to select a path from source to return as answer.

func (*Answer) Bool

func (a *Answer) Bool(d bool) (bool, bool)

Bool attempts asserting answer as a bool. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) Exists

func (a *Answer) Exists() bool

Exists returns a boolean indicating if the answer exists (not nil).

func (*Answer) Float

func (a *Answer) Float(d float64) (float64, bool)

Float attempts asserting answer as a float64. Casting from other number types will be done if necessary. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) Int

func (a *Answer) Int(d int64) (int64, bool)

Int attempts asserting answer as a int64. Casting from other number types will be done if necessary. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) Map

func (a *Answer) Map(d map[string]interface{}) (map[string]interface{}, bool)

Map attempts asserting answer as a map[string]interface{}. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) Path

func (a *Answer) Path(path string) *Answer

Path does the same thing as For but uses existing answer as source.

func (*Answer) Slice

func (a *Answer) Slice(d []interface{}) ([]interface{}, bool)

Slice attempts asserting answer as a []interface{}. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) String

func (a *Answer) String(d string) (string, bool)

String attempts asserting answer as a string. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) Uint

func (a *Answer) Uint(d uint64) (uint64, bool)

Uint attempts asserting answer as a uint64. Casting from other number types will be done if necessary. The first return value is the result, and the second indicates if the operation was successful. If not successful the first return value will be set to the d parameter.

func (*Answer) Value

func (a *Answer) Value() interface{}

Value returns the raw value as type interface{}, can be nil if no value is available.

Source Files

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