README
¶
unstruct
unstruct is a library to read external values and decode them into the structs.
unstruct reads values from external sources using Source interface.
It is very simple interface, so you can easily implement custom Source.
Synopsis
import (
"fmt"
"os"
"github.com/aereal/unstruct"
)
func main() {
decoder := unstruct.NewDecoder(unstruct.NewEnvironmentSource())
var val struct {
ExampleString string
ExampleInt int
ExampleBool bool
}
_ = decoder.Decode(&val)
}
See examples on pkg.go.dev.
Installation
go get github.com/aereal/unstruct
Motivation
The practical application may have various and complicated configuration.
If you build the configuration from external data sources, you may face issues like below:
- fetch from remote data sources
- the application must read secret data that like credentials from remote data sources using secure channels.
- initialization
- complicated configuration may have many fields; you must initialize all of them.
- validation:
- you have to check the existence of all of the mandatory fields.
- type conversions
- the application configuration may include some values that differs from strings, such as numbers, booleans, or anything else.
- external data sources may support just limited scalar types, so you have to convert/parse external values into the application configuration's values.
unstruct works as simple decoder that decodes external data into Go's values like encoding/json.
License
See LICENSE file.
Documentation
¶
Overview ¶
Package unstruct is a library to read external values and decode them into the structs.
Example ¶
package main
import (
"fmt"
"os"
"github.com/aereal/unstruct"
)
func main() {
decoder := unstruct.NewDecoder(unstruct.NewEnvironmentSource())
var val struct {
ExampleString string
ExampleInt int
ExampleBool bool
}
os.Setenv("EXAMPLE_STRING", "str")
os.Setenv("EXAMPLE_INT", "42")
os.Setenv("EXAMPLE_BOOL", "true")
if err := decoder.Decode(&val); err != nil {
panic(err)
}
fmt.Printf("%#v", val)
}
Output: struct { ExampleString string; ExampleInt int; ExampleBool bool }{ExampleString:"str", ExampleInt:42, ExampleBool:true}
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrInvalidTarget = errors.New("target must be a pointer to the struct") ErrValueNotFound = errors.New("no value found") )
Functions ¶
This section is empty.
Types ¶
type DecodeFieldError ¶
type DecodeFieldError struct {
// Field is a struct field that error occurs.
Field reflect.StructField
// Err is an error that occurs.
Err error
}
DecodeFieldError is an error type represents the decode failure on the field.
func (*DecodeFieldError) Error ¶
func (e *DecodeFieldError) Error() string
func (*DecodeFieldError) Is ¶
func (e *DecodeFieldError) Is(other error) bool
func (*DecodeFieldError) Unwrap ¶
func (e *DecodeFieldError) Unwrap() error
type Decoder ¶
type Decoder struct {
// contains filtered or unexported fields
}
Decoder runs data sources against given target value and completes target value.
func NewDecoder ¶
type EnvironmentSource ¶
type EnvironmentSource struct {
// contains filtered or unexported fields
}
EnvironmentSource is a Source that reads values from environment variables.
func NewEnvironmentSource ¶
func NewEnvironmentSource(opts ...EnvironmentSourceOption) *EnvironmentSource
type EnvironmentSourceOption ¶
type EnvironmentSourceOption func(*environmentSourceConfig)
func WithPrefix ¶
func WithPrefix(prefix string) EnvironmentSourceOption
WithPrefix indicates the EnvironmentSource fetches environment variables with given prefix.
func WithSliceDelimiter ¶
func WithSliceDelimiter(delimiter string) EnvironmentSourceOption
type MapSource ¶ added in v0.3.0
type MapSource struct {
// contains filtered or unexported fields
}
MapSource is a Source that fills values from given the map.
func NewMapSource ¶ added in v0.3.0
type Path ¶
type Path []reflect.StructField
type Source ¶
Source is an interface that fetches the values from external sources and fills into given target.
type UnsupportedTypeError ¶
type UnsupportedTypeError = internal.UnsupportedTypeError
UnsupportedTypeError is an error type represents target value type is not supported by Source.
Source Files
Directories