Flattened Entities Approach 1 : Siren for Ruby's ActiveModelSerializer

01-01-has-many.json

{
  "class": ["post"],
  "properties": {
    "id": 1,
    "title": "New Post",
    "body":  "Body"
  },
  "links": [{"rel": ["self"],"href": "http: //example.com/posts/1"}],
  "entities": [
    {
      "class":  ["tag"],
      "rel": ["http: //rels.example.com/tag","hasMany"],
      "properties": {"id": 1, "label": "foo"},
      "links": [{"rel": ["self"], "href": "http://example.com/tags/1"}]
    },
    {
      "class":  ["tag"],
      "rel": ["http: //rels.example.com/tag","hasMany"],
      "properties": {"id": 2, "label": "bar"},
      "links": [{"rel": ["self"], "href": "http://example.com/tags/2"}]
    },
    {
      "class":  ["tag"],
      "rel": ["http: //rels.example.com/tag","hasMany"],
      "properties": {"id": 3, "label": "baz"},
      "links": [{"rel": ["self"], "href": "http://example.com/tags/3"}]
    },
    {
      "class":  ["comment"],
      "rel": ["http: //rels.example.com/comment","hasMany"],
      "properties": {"id": 1, "body": "ZOMG A COMMENT"},
      "links": [{"rel": ["self"], "href": "http://example.com/comments/1"}]
    },
    {
      "class":  ["comment"],
      "rel": ["http: //rels.example.com/comment","hasMany"],
      "properties": {"id": 2, "body": "ZOMG ANOTHER COMMENT"},
      "links": [{"rel": ["self"], "href": "http://example.com/comments/2"}]
    }
  ]
}

01-02-has-many-include-comments.json

{
  "class": ["post"],
  "properties": {
    "id": 1,
    "title": "New Post",
    "body":  "Body"
  },
  "links": [{"rel": ["self"],"href": "http: //example.com/posts/1"}],
  "entities": [
    {
      "class":  ["tag"],
      "rel": ["http: //rels.example.com/tag","hasMany"],
      "properties": {"id": 1, "label": "foo"},
      "links": [{"rel": ["self"], "href": "http://example.com/tags/1"}]
    },
    {
      "class":  ["tag"],
      "rel": ["http: //rels.example.com/tag","hasMany"],
      "properties": {"id": 2, "label": "bar"},
      "links": [{"rel": ["self"], "href": "http://example.com/tags/2"}]
    },
    {
      "class":  ["tag"],
      "rel": ["http: //rels.example.com/tag","hasMany"],
      "properties": {"id": 3, "label": "baz"},
      "links": [{"rel": ["self"], "href": "http://example.com/tags/3"}]
    },
    {
      "class":  ["comment"],
      "rel": ["http: //rels.example.com/comment","hasMany"],
      "properties": {"id": 1, "body": "ZOMG A COMMENT"},
      "links": [{"rel": ["self"], "href": "http://example.com/comments/1"}],
      "actions": [
        {"name": "delete", "method": "DELETE", "href": "http://example.com/comments/1"},
        {"name": "update", "method": "PATCH", "href": "http://example.com/comments/1",       "fields": [ {"name": "body" }]}
      ]
    },
    {
      "class":  ["comment"],
      "rel": ["http: //rels.example.com/comment","hasMany"],
      "properties": {"id": 2, "body": "ZOMG ANOTHER COMMENT"},
      "links": [{"rel": ["self"], "href": "http://example.com/comments/2"}],
      "actions": [
        {"name": "delete", "method": "DELETE", "href": "http://example.com/comments/2"},
        {"name": "update", "method": "PATCH", "href": "http://example.com/comments/2",       "fields": [ {"name": "body"}]}
      ]
    }
  ]
}