json¶

The json driver reads values from JSON files.

import "github.com/insei/tinyconf/drivers/json"

jsonDriver, err := json.New("config.json")

Keys¶

The json tag is a key in the file. Tags of nested structs are keys of nested objects:

type Config struct {
    Name string `json:"name"`
    HTTP struct {
        Host string `json:"host"`
        Port int    `json:"port"`
    } `json:"http"`
    Hosts []string `json:"hosts"`
}

{
  "name": "app",
  "http": {
    "host": "example.com",
    "port": 9090
  },
  "hosts": ["a", "b"]
}

Options after the comma are ignored: json:"port,omitempty" is the port key. Set the json tag on all parents of the field: without the tag of the parent the field is read from the root of the file, and the manager logs a warning. Embedded structs without the tag are the exception, their fields are on the level of the embedding struct.

Options¶

The options are the same as in the yaml driver:

jsonDriver, err := json.New("config.json",
    json.WithFiles("config.local.json"),
    json.WithOptional(),
    json.WithEnvExpansion(),
)

Option	Description
`WithFiles(files...)`	additional files from the OS file system
`WithFS(fsys, files...)`	files from any `fs.FS`, `embed.FS` for example
`WithData(name, data)`	in-memory content, the name is used in error messages
`WithSource(source)`	content from a remote storage: `consul.Document`
`WithOptional()`	files can be absent
`WithEnvExpansion()`	replaces `${VAR}` and `${VAR:-default}` in the content with environment variables
`WithWatchInterval(interval)`	interval of polling the files for reloading, 5 seconds by default; changes are detected by the events of the file system without waiting for it

Several files are merged in the order of addition, objects are merged by keys. Files are read once per Parse call.

Documentation¶

GenDoc("json") generates a JSON document with all fields and their current values:

{
  "hosts": [
    "a",
    "b"
  ],
  "http": {
    "host": "example.com",
    "port": 9090
  },
  "name": "app"
}

JSON has no comments, so the doc tags are not used. Values of the fields with hidden:"true" are replaced with empty strings.