sqlite中使用json_extract从父子对象中拉取数据

Question

I'm starting to explore the JSON1 library for sqlite and have been so far successful in the basic queries I've created. I'm now looking to create a more complicated query that pulls data from multiple levels.

Here's the example JSON object I'm starting with (and most of the data is very similar).

{
  "height": 140.0,
  "id": "cp",
  "label": {
    "bind": "cp_label"
  },
  "type": "color_picker",
  "user_data": {
    "my_property": 2
  },
  "uuid": "948cb959-74df-4af8-9e9c-c3cb53ac9915",
  "value": {
    "bind": "cp_color"
  },
  "width": 200.0
}

This json object is buried about seven levels deep in a json structure and I pulled it from the larger json construct using an sql statement like this:

SELECT value FROM forms, json_tree(forms.formJSON, '$.root') 
WHERE type = 'object'
    AND json_extract(value, '$.id') = @sControlID

// In this example, @sControlID is a variable that represents the `id` value we're looking for, which is 'cp'

But what I really need to pull from this object are the following:

• the value from key type ("color_picker" in this example)
• the values from keys bind ("cp_color" and "cp_label" in this example)
• the keys value and label (which have values of {"bind":"<string>"} in this example)

For that last item, the key name ( value and label in this case) can be any number of keywords, but no matter the keyword, the value will be an object of the form {"bind":"<some_string>"} . Also, there could be multiple keys that have a bind object associated with them, and I'd need to return all of them. For the first two items, the keywords will always be type and bind .

With the json example above, I'd ideally like to retrieve two rows:

type          key     value
color_picker  value   cp_color
color_picker  label   cp_label

When I use json_extract methods, I end up retrieving the object {"bind":"cp_color"} from the json_tree table, but I also need to retrieve the data from the parent object. I feel like I need to do some kind of union, but my attempts have so far been unsuccessful. Any ideas here?

Note: if the {"bind":"<string>"} object doesn't exist as a child of the parent object, I don't want any rows returned.

Answer 1

Well, I was on the right track and eventually figured out it. I created a separate query for each of the items I was looking for, then INNER JOIN ed all the json_tree tables from each of the queries to have all the required fields available. Then I json_extract ed the required data from each of the json fields I needed data from. In the end, it gave me exactly what I was looking for, though I'm sure it could be written more efficiently.

For anyone interested, this is what hte final query ended up looking like:

SELECT IFNULL(json_extract(parent.value, '$.type'), '_window_'), child.key, json_extract(child.value, '$.bind') FROM (SELECT json_tree.* FROM nui_forms, json_tree(nui_forms.formJSON, '$') WHERE type = 'object' AND json_extract(nui_forms.formJSON, '$.id') = @sWindowID) parent INNER JOIN (SELECT json_tree.* FROM nui_forms, json_tree(nui_forms.formJSON, '$') WHERE type = 'object' AND json_extract(value, '$.bind') != 'NULL' AND json_extract(nui_forms.formJSON, '$.id') = @sWindowID) child ON child.parent = parent.id;

If you have any tips on reducing its complexity, feel free to comment!