structs

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structs

structs provides utility features related of the struct.

Features

• propagation struct fields
• output diff struct fields

propagation struct fields

struct fields in the struct can be copied from variable A to B.

Usage

package structs_test

import (
	"fmt"

	"github.com/takashabe/structs"
)

func ExamplePropagateValues() {
	type User struct {
		ID   int
		Name string
		Age  int
	}

	a := &User{ID: 1, Name: "foo", Age: 1}
	b := &User{ID: 2, Name: "bar", Age: 2}
	got, _ := structs.PropagateValues(
		a,
		b,
		structs.PropagateWithIgnoreFields("ID", "Name"),
		structs.PropagateWithValue(1),
	)
	fmt.Printf("%+v", got)

	// Output:
	// &{ID:2 Name:bar Age:1}
}

output diff struct fields

provide output of field names with different values

Usage

func ExampleDiffFields() {
	type User struct {
		ID     int         `json:"id"`
		Name   string      `json:"name"`
		Age    int         `json:"age"`
		Gender null.String `json:"gender"`
	}

	a := &User{ID: 1, Name: "foo", Age: 1, Gender: null.StringFrom("Male")}
	b := &User{ID: 2, Name: "bar", Age: 1}
	got, _ := structs.DiffFields(
		a,
		b,
	)
	fmt.Printf("%+v", got)

	// Output:
	// [id name gender]
}

Documentation

Index

• Variables
• func DiffFields[T, T2 any](src T, dst T2, opts ...Option) ([]string, error)
• func PropagateValues[T, T2 any](src T, dst T2, opts ...Option) (T2, error)
• type Option
  • func WithDefaultValue() Option
  • func WithIgnoreFields(names ...string) Option
  • func WithIgnoreSourceDefaultValue() Option
  • func WithTargetFields(names ...string) Option
  • func WithValue(v any) Option

Examples

• DiffFields
• PropagateValues

Variables

var DiffTagName = "json"

Functions

func DiffFields

func DiffFields[T, T2 any](src T, dst T2, opts ...Option) ([]string, error)

DiffFields returns different field names

Example

type User struct {
	ID     int         `json:"id"`
	Name   string      `json:"name"`
	Age    int         `json:"age"`
	Gender null.String `json:"gender"`
}

a := &User{ID: 1, Name: "foo", Age: 1, Gender: null.StringFrom("Male")}
b := &User{ID: 2, Name: "bar", Age: 1}
got, _ := structs.DiffFields(
	a,
	b,
)
fmt.Printf("%+v", got)

Output:

[id name gender]

func PropagateValues

func PropagateValues[T, T2 any](src T, dst T2, opts ...Option) (T2, error)

PropagateValues copy from `src` field values to `dst`.

Example

package main

import (
	"fmt"

	"github.com/takashabe/structs"
)

func main() {
	type User struct {
		ID   int
		Name string
		Age  int
	}

	a := &User{ID: 1, Name: "foo", Age: 1}
	b := &User{ID: 2, Name: "bar", Age: 2}
	got, _ := structs.PropagateValues(
		a,
		b,
		structs.WithIgnoreFields("ID", "Name"),
		structs.WithValue(1),
	)
	fmt.Printf("%+v", got)

}

Output:

&{ID:2 Name:bar Age:1}

Types

type Option

type Option func(srcValue, dstValue reflect.Value, srcField reflect.StructField) bool

Option represents whether to target field.

func WithDefaultValue

func WithDefaultValue() Option

WithDefaultValue valid when the field in dst is a type-specific default value.

func WithIgnoreFields

func WithIgnoreFields(names ...string) Option

func WithIgnoreSourceDefaultValue

func WithIgnoreSourceDefaultValue() Option

WithIgnoreSourceDefaultValue not valid if the src field is a type-specific default value.

func WithTargetFields

func WithTargetFields(names ...string) Option

func WithValue

func WithValue(v any) Option