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Updated readme with the new JSON additions

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Álvaro 2016-01-20 23:09:18 +00:00
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#Enumer #Enumer
Enumer generates Go code to get string names from enum values and viceversa. Enumer is a tool to generate Go code that adds useful methods Go enums (constants with a specific type)
It is a fork of [Rob Pike’s Stringer tool](https://godoc.org/golang.org/x/tools/cmd/stringer) It started as a fork of [Rob Pike’s Stringer tool](https://godoc.org/golang.org/x/tools/cmd/stringer).
but adding a *"string to enum value"* method to the generated code.
This is useful when you need to read enum values from the command line arguments, from a configuration file, #Generated functions and methods
When Enumer is applied to a type, it will generate three methods and one function:
* A method `String()` that returns the string representation of the enum value. This makes the enum conform
the `Stringer` interface, so whenever you print an enum value, you'll get the string name instead of a number.
* A function `<Type>String(s string)` to get the enum value from its string representation. This is useful
when you need to read enum values from the command line arguments, from a configuration file,
from a REST API request... In short, from those places where using the real enum value (an integer) would from a REST API request... In short, from those places where using the real enum value (an integer) would
be almost meaningless or hard to trace or use by a human be almost meaningless or hard to trace or use by a human.
* And two more methods, `MarshalJSON()` and `UnmarshalJSON()`, that makes the enum conform to
the `json.Marshaler` and `json.Unmarshaler` interfaces. Very useful to use it in JSON APIs.
For example, if we have an enum type called `Pill`, For example, if we have an enum type called `Pill`,
```go ```go
@ -19,7 +26,7 @@ const (
Acetaminophen = Paracetamol Acetaminophen = Paracetamol
) )
``` ```
executing `enumer -type=Pill` will generate a new file with two methods: executing `enumer -type=Pill` will generate a new file with four methods:
```go ```go
func (i Pill) String() string { func (i Pill) String() string {
//... //...
@ -28,6 +35,14 @@ func (i Pill) String() string {
func PillString(s string) (Pill, error) { func PillString(s string) (Pill, error) {
//... //...
} }
func (i Pill) MarshalJSON() ([]byte, error) {
//...
}
func (i *Pill) UnmarshalJSON(data []byte) error {
//...
}
``` ```
From now on, we can: From now on, we can:
```go ```go
@ -43,11 +58,17 @@ if err != nil {
return return
} }
// Now pill == Ibuprofen // Now pill == Ibuprofen
// Or marshal/unmarshal to/from json strings
``` ```
The generated code is exactly the same as the Stringer tool plus the `<Type>String` method, so you can use The generated code is exactly the same as the Stringer tool plus the mentioned additions, so you can use
**Enumer** where you are already using **Stringer** without any code change. **Enumer** where you are already using **Stringer** without any code change.
## How to use ## How to use
The usage of Enumer is the same as Stringer, no changes were introduced. The usage of Enumer is the same as Stringer, so you can refer to the [Stringer docs](https://godoc.org/golang.org/x/tools/cmd/stringer)
For more information please refer to the [Stringer docs](https://godoc.org/golang.org/x/tools/cmd/stringer) for more information.
There is only one flag added: `noJSON`. If this flag is set to true (i.e. `enumer -type=Pill -noJSON`),
the JSON related methods won't be generated.