glom

glom

This is based on the Python module/package glom.

Installation

Should be go get github.com/beanzilla/glom (Should automatically get structs)

Basic Example

/* For brevity I will be showing a basic structure in a Pythonic format (Looks simular to JSON or HJSON)

// See Example Data section below for how this structure would/could look in Go.

data = { // Assume data is map[string]interface{}
    "users": {
    	"Bob": {
        	"last-on": "some time ago",
        	"age": 42,
        	"sec-level": 99
    	},
    	"Phil": {
	          "last-on": "a few seconds ago",
    	      "age": 0,
        	  "sec-level": 10
      	}
    },
    "posts": [
        {
            "title": "Why Glom-Go Rocks!",
            "post-date": "a few weeks ago",
            "description": "Access nested structures with ease, especially mixed types like map, slice/array, and interface.",
            "line-count": 1,
            "likes": 0
        },
        {
            "title": "Example of Glom-Go, and 5 other neat tips",
            "post-date": "a few months ago",
            "description": "Example in example... See recursion.",
            "line-count": 1,
            "likes": 0
        }
    ]
}
*/

// Let's start with something simple, getting the last time Bob was on...
bob_last_on, err := glom.Glom(data, "users.Bob.laston")
// In Python it would be data["users"]["Bob"]["laston"] (But in Go, we can't do that, due to our base type of data... interface)

if err != nil {
    fmt.Println(err) // Oops, and error occured, Looks like the error would be something like...
    // Failed moving to 'laston' from path of 'users.Bob', options are 'last-on', 'age', 'sec-level' (3)
    // So as the error is trying to let us know, we miss typed last-on with laston.
} else {
    fmt.Printf("Bob was last on %v.", bob_last_on) // If you fixed it so the string passed to glom.Glom was "users.Bob.last-on"
    // You now get:
    // Bob was last on some time ago.
}

// Now let's access the likes of the second post...
second_post_likes, err := glom.Glom(data, "posts.1.likes") // Remember slices/arrays start at 0, so the index of 1 will give us the second.

if err != nil {
    fmt.Println(err)
} else {
    fmt.Printf("Post 2 got %v likes.", second_post_likes)
    // Post 2 got 0 likes.
}

Example Data

This part was separated due to it's length and complexity. (It is added to allow the above example to actually work, just copy this then copy the Basic Example, above)

// Initalize a multi-layer structure (I will try my best to show the layers deep, where 1 is directly accessable)
data := make(map[string]interface{})

// 1 can be like `data["users"]`
// 2 (which can't be directly accessed without some interface casting) can be `data["users"]["Bob"]`
// 3 (which can't be directly accessed without some nested interface casting) can be `data["users"]["Bob"]["sec-level"]`

users := make(map[string]interface{}) // 1

bob := make(map[string]interface{}) // 2
bob["last-on"] = "some time ago" // 3
bob["age"] = 42 // 3
bob["sec-level"] = 99 // 3
users["Bob"] = bob // Add Bob to users

phil := make(map[string]interface{}) // 2
phil["last-on"] = "a few seconds ago" // 3
phil["age"] = 0 // 3
phil["sec-level"] = 10 // 3
users["Phil"] = phil // Add Phil to users

data["users"] = users // Add users to data

var posts []interface{} // 1

post1 := make(map[string]interface{}) // 2
post1["title"] = "Why Glom-Go Rocks!" // 3
post1["post-date"] = "a few weeks ago" // 3
post1["description"] = "Access nested structures with ease, especially mixed types like map, slice/array, and interface." // 3
post1["line-count"] = 1 // 3
post1["likes"] = 0 // 3
posts = append(posts, post1) // Add post1 to posts

post2 := make(map[string]interface{}) // 2
post2["title"] = "Example of Glom-Go, and 5 other neat tips" // 3
post2["post-date"] = "a few months ago" // 3
post2["description"] = "Example in example... See recursion." // 3
post2["line-count"] = 1 // 3
post2["likes"] = 0 // 3
posts = append(posts, post2) // Add post2 to posts

data["posts"] = posts // Add posts to data

// data is now ready for glom.Glom

Basic Accessing

Python's glom made accessing nested structures a breeze, glom was built to attempt to do just that just for Go.

• Just use dot notation for accessing/walking your data. (I.E. users.Bob.age would access the 3rd level, and comes with Python's glom error messaging showing exactly where while it walked the data it got lost at/couldn't go)
• Special star for dot notation. (I.E. to get all the users you could users or even users.*)
• glom can support maps, slices/arrays, and structures (specifically it's fields that are public/exposed), making it rather extensive.

Under the hood

glom uses reflect and structs to handle nesting thru various structures.

From []interface{} to map[string]interface{} (Even map[int]interface{} works).

All while supporting custom structures...

type User struct {
    Name string
    Last_on string
    Age int
}

type Post struct {
    Title string
    Description string
    Line_count int
    Author User
    Post_date string
}

type Blog struct {
    Site_name string
    Posts []Post
    Site_owner User
}
bob := User{"Bob", "some time ago", 42}
blog := Blog{Site_name: "Test Site", Site_Owner: bob}
blog.Posts = append(blog.Posts, Post{"Example of Structs with glom", "Yet another example of Glom-Go", 1, bob, "a few seconds ago"})

// Example of accessing that to get first post's author
post_owner, err := glom.Glom(blog, "Posts.0.Author.Name")
if err != nil {
    fmt.Println(err)
} else {
    fmt.Printf("%v wrote the first post!", post_owner)
    // Bob wrote the first post!
}