[Custom Source] Parsing JSON in to cmp readable table.

[rudfol]

Hi,

The difficulty I have is understanding what kind items cmp accepts. One item would be 'label' which I understand to be
used as an entry in the completion window.
To create a custom source I've used the template you provided.

The format of this JSON file I copied from the rafamadriz /friendly-snippets json files inside snippet folder.

So far the result I get is nothing. 👎

Expected results would be 'MediaItem reaper.AddMediaItemToTrack'
(residing in the first curly bracket)
to be used as a title on the documentation window,

contents of 'prefix:' for label,

what's in the 'body' for completion (snippetable) and

the content of 'description:' for documentation.

How should I go about doing this please?

P.S I have already added the source to the cmp config and confirmed that the default template you provided for 'month' works.

[rudfol]

So far I've read multiple cmp sources and from what I understand below should work, just absolutely no idea why it does not however.

I will be continuing to work on this, but I would loveee a pointer in the right direction please.

[rudfol]

For anyone looking for answers:

'- #input' <-- is for replacing what you already typed with a completion rather than completion concatenating on to what you typed.

the definition of things like 'label' and 'InsertTextMode' go see LSP Spec at: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/

[joe-dil]

I created a plugin to parse JSON and extract fields to be used for completions, check it out joe-dil/json-cmp

[rudfol]

that's pretty awesome, because it looks so easy to use. Cheers for the work on that

[rudfol]

I am back to setting up my own source with blink.cmp after many years and dayuuum, i don't even know what the hell is going on. I forgot all of it loool

[kinthaiofficial]

Writing a custom nvim-cmp source is well-documented once you find the right examples. The key is the source object interface:

local source = {}

-- Required: return source name
source.get_trigger_characters = function()
  return { '.', ':' }
end

-- Required: provide completion items
source.complete = function(self, params, callback)
  local items = {}
  
  -- params.context has cursor position, buffer info, etc.
  local bufnr = params.context.bufnr
  
  -- Build your items
  table.insert(items, {
    label = 'my_completion',
    kind = require('cmp').lsp.CompletionItemKind.Text,
    detail = 'My custom completion',
    documentation = {
      kind = 'markdown',
      value = '**Description**\n\nThis is my item'
    },
  })
  
  callback({ items = items, isIncomplete = false })
end

-- Register the source
require('cmp').register_source('my_source', source)

For JSON parsing to cmp table:

source.complete = function(self, params, callback)
  local json_str = vim.fn.system('your-command-that-returns-json')
  local ok, data = pcall(vim.json.decode, json_str)
  
  if not ok then
    callback({ items = {}, isIncomplete = false })
    return
  end
  
  local items = vim.tbl_map(function(entry)
    return {
      label = entry.name,
      detail = entry.type,
      documentation = entry.description,
    }
  end, data)
  
  callback({ items = items })
end

Async sources: for slow data (API calls, filesystem), use callback asynchronously — don't block the complete function. Use vim.schedule or plenary.async to keep the event loop responsive.

Sorting/filtering: cmp handles fuzzy matching on labels automatically. You just need to return the candidate set.

What's the data source for your JSON — an external API, a local file, or a tool output?