decoder

README

Package decoder - this unmarshals or decodes values from a consul KV store into a struct. The following types are supported:

• Integer (int/int8/int16/int32/int64)

• Unsigned (uint/uint8/uint16/uint32/uint64)

• Float (float64/float32)

• time.Duration

• net.IP

• net.IPMask

• struct - nested struct by default implies a consul folder with the same name. if the tag modifier "json" is encountered, then the value of in the KV is unmarshaled as json using json.Unmarshal

• slice - the type can be most of the supported types, except another slice.

• map - the key must be a string, the value can be anything but another map.

Struct tags By default, the decoder packages looks for the struct tag "decoder". However, this can be overridden inside the Decoder struct as shown below. For the purposes of examples, we'll stick with the default "decoder" tag.

    struct Foo {

     // populate the value from key "whatever" into FooField1
     FooField1 string `decoder:"whatever"`

     // skip populating FooField2, "-" signals skip
     FooField2 string `decoder:"-"`

     // this looks for a folder named FooField3
     // and maps keys inside to the keys / values of the map.  string
     // is the only valid key type, though the map value can be most any
     // of the other types supported by this package.  Notable exception
     // map, as nested maps are not allowed.  You can, however, have a
     // map[string]SomeStruct.
     FooField3 map[string]string

     // this looks for a folder named FooField4 (case insensitive)
     // this is similar to the map example above, but it ignores the keys
     // inside and maps the values in-order into the slice.  nested slices
     // are not allowed, i.e., [][]string.
     FooField4 []string

     // this interprets the value of foofield5 as json data and
     // will send it to json.Unmarshal from encoding/json package.
     FooField5 *SomeStruct `decoder:"foofield5,json"`

}

Documentation

Overview

Package decoder - this unmarshals or decodes values from a consul KV store into a struct. The following types are supported:

Integer (int/int8/int16/int32/int64)
Unsigned (uint/uint8/uint16/uint32/uint64)
Float (float64/float32)
time.Duration
net.IP
net.IPMask
struct - nested struct by default implies a consul folder with the same name.
         if the tag modifier "json" is encountered, then the value of in the KV
         is unmarshaled as json using json.Unmarshal
slice - the type can be most of the supported types, except another slice.
map - the key must be a string, the value can be anything but another map.

Struct tags

By default, the decoder packages looks for the struct tag "decoder". However, this can be overridden inside the Decoder struct as shown below. For the purposes of examples, we'll stick with the default "decoder" tag. By default, in the absense of a decoer tag, it will look for a consul key name with the same name as the struct field. Only exported struct fields are considered. The name comparison is case-insensitive. the tag "-" indicates to skip the field. The modifier ",json" appended to the end signals that the value is to be interpreted as json and unmarshaled.

 struct Foo {

     // populate the value from key "whatever" into FooField1
     FooField1 string `decoder:"whatever"`

     // skip populating FooField2, "-" signals skip
     FooField2 string `decoder:"-"`

     // this looks for a folder named FooField3
     // and maps keys inside to the keys / values of the map.  string
     // is the only valid key type, though the map value can be most any
     // of the other types supported by this package.  Notable exception
     // map, as nested maps are not allowed.  You can, however, have a
     // map[string]SomeStruct.
     FooField3 map[string]string

     // this looks for a folder named FooField4 (case insensitive)
     // this is similar to the map example above, but it ignores the keys
     // inside and maps the values in-order into the slice.  nested slices
     // are not allowed, i.e., [][]string.
     FooField4 []string

     // this interprets the value of foofield5 as json data and
     // will send it to json.Unmarshal from encoding/json package.
     FooField5 *SomeStruct `decoder:"foofield5,json"`

     // this expects there to be a consul folder foofield6 and that the
     // keys within will correspond to the fields inside SomeStruct type.
     FooField6 *SomeStruct `decoder:"foofield6"`

}

Index

• Variables
• func Unmarshal(pathPrefix string, kvps api.KVPairs, v interface{}) error
• type Decoder
  • func (d *Decoder) Unmarshal(pathPrefix string, kvps api.KVPairs, v interface{}) error
• type NameResolverFunc

Variables

var InvalidValueErr = errors.New("invalid value passed: must be a non-nil pointer to a struct")

InvalidValueErr - this is returned if we don't pass an appropriate type to Decode() or Unmarshal()

Functions

func Unmarshal

func Unmarshal(pathPrefix string, kvps api.KVPairs, v interface{}) error

Unmarshal - uses the default decoder with default settings to decode the values from kvps at pathPrefix into v.

Types

type Decoder

type Decoder struct {
	// If true, then field names must match key exactly.
	CaseSensitive bool
	// Be responsible, don't change this after being set.
	NameResolver NameResolverFunc
	// The struct tag to parse.  defaults to "decoder"
	Tag string
}

Decoder - define one of these if you want to override default behavior. Otherwise just use Unmarshal()

func (*Decoder) Unmarshal

func (d *Decoder) Unmarshal(pathPrefix string, kvps api.KVPairs, v interface{}) error

Unmarshal - this is the Unmarshal method on a custom decoder. Same as above otherwise.

type NameResolverFunc

type NameResolverFunc func(field, tag string) (key string)

NameResolverFunc - this allows us to define a custom name resolution to override the default.