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https://github.com/pungyeon/required
https://github.com/pungyeon/required
go golang json json-parser parser parsing parsing-library required-fields
Last synced: about 2 months ago
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- Host: GitHub
- URL: https://github.com/pungyeon/required
- Owner: Pungyeon
- License: apache-2.0
- Created: 2019-12-15T17:23:28.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2022-10-19T10:50:16.000Z (about 2 years ago)
- Last Synced: 2024-06-19T06:56:13.137Z (6 months ago)
- Topics: go, golang, json, json-parser, parser, parsing, parsing-library, required-fields
- Language: Go
- Homepage:
- Size: 207 KB
- Stars: 6
- Watchers: 3
- Forks: 3
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Required JSON tags
[](https://godoc.org/github.com/Pungyeon/required)
[](https://goreportcard.com/report/github.com/Pungyeon/required)
## Introduction
Long story short, a junior engineer at work asked me (a long time ago now). How to make `JSON` fields required. I didn't have a good answer for him, and after some short research it turns out that there isn't a good answer for this!
I therefore wrote the following article on making a package validating `JSON` input: [article/README.md](Original Article).
However, a delve into the rabbit hole later, I have made my own `JSON` parser, which does support required tags. It is definitely not a finished or production ready product, so all help and feedback is extremely welcome. The original article was meant to solve a problem, whereas the `JSON` parser spawned from pure curiosity.
## Usage
It should be possible to substitute the std `json` import with the current library, without issue.
If this is not the case, please make sure to report this as an issue here on GitHub :)
### JSON Unmarshalling
The usage is very simple. Adding the `JSON` struct tag "required", will have the parser enforce this field to be present, when unmarshalling:
```go
type User struct {
FirstName string `json:"first_name,required"`
LastName string `json:"last_name,required"`
Email string `json:"email,required"`
GitHub string `json:"github"`
LinkedIn string
}
```
In the above example, `FirstName`, `LastName` and `Email` are required, where as `GitHub` and `LinkedIn` are not.
```go
func main() {
var user User
if err := Unmarshal([]byte(`{}`), &user); err != nil {
panic(err) // this will return an error because of the missing required fields
}
fmt.Println(user)
}
```
Where as the following JSON string will parse without returning an error:
```go
`{
"first_name": "lasse",
"last_name": "jakobsen",
"email": "[email protected]"
}`
```
Furthermore, it is possible to implement the `Required` interface, to create custom validation of a type.
```go
type Required interface {
IsValueValid() error
}
```
Below is an example of implementing this interface for a type alias of `string` called `Email`. This will validate the string to adhere to the general structure of an e-mail. This means, that when being parsed, the `json` will be ensured to not only exist, but also that it's valid as defined in the `IsValidValue` function.
```go
type Email string
func (email Email) IsValueValid() error {
matched, err := regexp.MatchString(`.+@.+\..+`, string(email))
if err != nil {
return err
}
if !matched {
return errors.New("invalid email")
}
return nil
}
```
Refer to samples for a more detailed example of this.
### Marshalling
As of writing this document, this library is currently using a custom `json.Marshal` and `json.Encoder`. This library *does not currently support `required` tag checking*, please show your interest, if you would like this by creating a new issue. The `json.Marshal` function is compatible with the standard library functionality. Though, substantially faster:
```
goos: darwin
goarch: amd64
pkg: github.com/Pungyeon/required/pkg/json
BenchmarkMarshalStd-8 603121 1859 ns/op 752 B/op 12 allocs/op
BenchmarkMarshalPkg-8 729928 1581 ns/op 832 B/op 10 allocs/op
PASS
ok github.com/Pungyeon/required/pkg/json 2.445s
```