Add links/meta to the top document

[mbn18]

Hi, I cant seems to create a response like the one bellow (origin JsonAPI site)

{
    "meta": {
        "total-pages": 13
    },
    "data": [{
        "type": "articles",
        "id": "3",
        "attributes": {
            "title": "JSON API paints my bikeshed!",
            "body": "The shortest article. Ever.",
            "created": "2015-05-22T14:56:29.000Z",
            "updated": "2015-05-22T14:56:28.000Z"
        }
    }],
    "links": {
        "self": "http://example.com/articles?page[number]=3&page[size]=1",
        "first": "http://example.com/articles?page[number]=1&page[size]=1",
        "prev": "http://example.com/articles?page[number]=2&page[size]=1",
        "next": "http://example.com/articles?page[number]=4&page[size]=1",
        "last": "http://example.com/articles?page[number]=13&page[size]=1"
    }
}

I can get the data but could not figure how to add meta or links to the response. I could only add them under the data level

This is the struct

type Album struct {
	ID   int    `jsonapi:"primary,album"`
	Name string `jsonapi:"attr,name"`
}

First I tried []*Album but coludnt understand how to add meta/links to the slice
Then I created a wrapper struct

type Albums struct {
	Albums []*Album `jsonapi:"relation,albums"`
}

But the output was invalid (or at least not like the provided example)

What am I missing. How can I add meta/links to the top level. Thanks.

[aren55555]

You can do something like the following:

func main() {
	albums := []*Album{
		&Album{ID: 3, Name: "JSON API paints my bikeshed!"},
	}

	var m []interface{}
	for _, a := range albums {
		m = append(m, a)
	}
	payload, err := jsonapi.MarshalMany(m)
	if err != nil {
		panic(err)
	}

	payload.Meta = &jsonapi.Meta{
		"total-pages": 13,
	}

	payload.Links = &jsonapi.Links{
		"self":  "http://example.com/articles?page[number]=3&page[size]=1",
		"first": "http://example.com/articles?page[number]=1&page[size]=1",
		"prev":  "http://example.com/articles?page[number]=2&page[size]=1",
		"next":  "http://example.com/articles?page[number]=4&page[size]=1",
		"last":  "http://example.com/articles?page[number]=13&page[size]=1",
	}

	w := bytes.NewBuffer(nil)
	if err := json.NewEncoder(w).Encode(payload); err != nil {
		panic(err)
	}
	fmt.Println(w)
}

Which will print the following JSON:

{
    "data": [{
        "type": "album",
        "id": "3",
        "attributes": {
            "name": "JSON API paints my bikeshed!"
        }
    }],
    "links": {
        "first": "http://example.com/articles?page[number]=1&page[size]=1",
        "last": "http://example.com/articles?page[number]=13&page[size]=1",
        "next": "http://example.com/articles?page[number]=4&page[size]=1",
        "prev": "http://example.com/articles?page[number]=2&page[size]=1",
        "self": "http://example.com/articles?page[number]=3&page[size]=1"
    },
    "meta": {
        "total-pages": 13
    }
}

[imhuytq]

@aren55555 Now, MarshalMany isn't public function, how can I use it?

[aren55555]

@pp4p since posting that sample code the Marshal API has been significantly simplified. You no longer need to populate a slice of interfaces []interface{}. Furthermore, Marshal first return will be a value that implements the Payloader interface. Since we passed Marshal a slice, the Payloader returned will always be a *jsonapi.ManyPayload.

You can now get away with just doing main.go:

package main

import (
	"bytes"
	"encoding/json"
	"fmt"

	"github.com/google/jsonapi"
)

type Album struct {
	ID   int    `jsonapi:"primary,album"`
	Name string `jsonapi:"attr,name"`
}

type Albums struct {
	Albums []*Album `jsonapi:"relation,albums"`
}

func main() {
	albums := []*Album{
		&Album{ID: 3, Name: "JSON API paints my bikeshed!"},
	}

	p, err := jsonapi.Marshal(albums)
	if err != nil {
		panic(err)
	}

	payload, ok := p.(*jsonapi.ManyPayload)
	if !ok {
		panic(fmt.Errorf("was not a many payloader"))
	}

	payload.Meta = &jsonapi.Meta{
		"total-pages": 13,
	}

	payload.Links = &jsonapi.Links{
		"self":  "http://example.com/articles?page[number]=3&page[size]=1",
		"first": "http://example.com/articles?page[number]=1&page[size]=1",
		"prev":  "http://example.com/articles?page[number]=2&page[size]=1",
		"next":  "http://example.com/articles?page[number]=4&page[size]=1",
		"last":  "http://example.com/articles?page[number]=13&page[size]=1",
	}

	w := bytes.NewBuffer(nil)
	if err := json.NewEncoder(w).Encode(payload); err != nil {
		panic(err)
	}
	fmt.Println(w)
}

go run main.go will produce:

{
    "data": [{
        "type": "album",
        "id": "3",
        "attributes": {
            "name": "JSON API paints my bikeshed!"
        }
    }],
    "links": {
        "first": "http://example.com/articles?page[number]=1\u0026page[size]=1",
        "last": "http://example.com/articles?page[number]=13\u0026page[size]=1",
        "next": "http://example.com/articles?page[number]=4\u0026page[size]=1",
        "prev": "http://example.com/articles?page[number]=2\u0026page[size]=1",
        "self": "http://example.com/articles?page[number]=3\u0026page[size]=1"
    },
    "meta": {
        "total-pages": 13
    }
}

[imhuytq]

@aren55555 thank you.

[mrhwick]

I thought about submitting a PR to implement this in the library, since the official site recommends top level links be included alongside resource-level and relationship links. I think it's important to keep the library simple, so I decided against writing this feature into the library. Would it make sense to write some documentation for how to achieve this recommended functionality.

[rberlind]

The solution provided here only addresses marshaling links into a structure. We also need a solution for unmarshalling links from a structure that uses jsonapi structure tags for other fields. Adding additional links/meta tags to the top document as the original poster requested would really make the jsonapi much easier to use. And while an example of the solution given in #68 is provided in https://github.com/google/jsonapi/blob/master/request_test.go#L694, that example does not show how to demarshal a structure that uses jsonapi structure tags.