nohupped/simplejson

{ SimpleJSON }

A lame attempt to re-create python's json.loads() using Get() methods to retrive a key by moving the ugly typeassertions to the library.

Why

This is just a wrapper over go's encoding/json. This uses an interface{} to unmarshal the json and the exposed interface method Get() uses type assertions internally to get the value of a key if it is a hashmap or the index if it is an array. Since this moves the ugly typeassertions for nested json parsing inside the library, the code becomes easier to read.

Example

Consider the json string

sampleJSON := `{
    "Actors":
    [
        {
            "name": "Tom Cruise",
            "age": 56,
            "Born At": "Syracuse, NY",
            "Birthdate": "July 3, 1962",
            "hasChildren":true,
            "hasTwitterAccount":true,
            "hasGreyHair":false,
            "photo": "https://jsonformatter.org/img/tom-cruise.jpg"
        },
        {
            "name": "Robert Downey Jr.",
            "age": 53,
            "Born At": "New York City, NY",
            "Birthdate": "April 4, 1965",
            "photo": "https://jsonformatter.org/img/Robert-Downey-Jr.jpg"
        }
    ]
}`

This can be parsed and values can be fetched as

d, err := simplejson.Loads(sampleJSON)
if err != nil {
    panic(err)
}
data := d.Get("Actors").Get("", 0).Get("name")
fmt.Println(data) // outputs Tom Cruise

Consider the json file samplejson.json in this repository.

This file can be parsed and the values can be fetched as

fd, err := os.Open("samplejson.json")
if err != nil {
    panic(err)
}
d1, err := Load(fd)
if err != nil{
    panic(err)
}
t.Logf("%s", d1.Get("", 2).Get("tags").Get("", 3))

fd.Close()

It is the responsibility of the caller to close the file descriptor.

Because this uses interface{} to unmarshal json, the structure of json is not required to be predefined. Each Get() evaluates the type and extracts accordingly.

Get() function panics returns nil for the method Bytes() if the key is not present

Instead of returning an error, Get() function panics returns nil for the Bytes() method when trying to fetch an invalid key or trying to read from an invalid index. This is done to easily chain the method as follows

Get("foo").Get("bar").Get("", 2)

without having to evaluate for errors every time or to have to write a recover as below.

defer func() {
    if r := recover(); r != nil {...}

Evaluate for nil value before using it.

Eg:

d, err := simplejson.Loads([]byte(sampleJSON))
if err != nil {
    ...
}
d1 := d.Get("Actors").Get("", 0).Get("names").Get("foo").Get("Bar")
if d1.Bytes != nil {
    ...
}
...

String() function returns empty string "" for nil values

This is done to avoid the

panic: runtime error: invalid memory address or nil pointer dereference

at runtime. Evaluate for nil value before applying String() method.