Is set_icon_by_filetype working?

[rodhash]

Hi,

My goal is to set a custom icon for TelescopePrompt buffers however the Filetype function doesn't seem to work.

If I use override_by_extension (commented out) it works just fine but with set_icon_by_filetype I'm unable to set a custom icon.

Here a simple test with .norg files (works only with override_by_extension):

      local devicons = require("nvim-web-devicons")

      devicons.set_icon_by_filetype({ toml = "bmp", foo = "bar", cpp = "x", norg = "y" })

      -- devicons.setup{
      --   override_by_extension = {
      --     ["norg"] = {
      --       icon = "z",
      --       color = "#519aba",
      --       name = "Norg",
      --     },
      --
      --   }
      --
      -- }

Is there a way to set custom icon for buffers like TelescopePrompt inside setup func?

I didn't find something like override_by_filetype in the docs so I guess this has to be done with set_icon_by_filetype but for some reason this particular one isn't working for me.

[alex-courtis]

set_icon_by_filetype maps a filetype to an existing icon.

You'll need to add/override your icon by extension, then may a filetype to it, something like

require("nvim-web-devicons").set_icon {
  ["c"] = {
    icon = "x",
    color = "#599EFF",
    cterm_color = "111",
    name = "C"
  },
}

require("nvim-web-devicons").set_icon_by_filetype({ cpp = "c", })

RE telescope icons, check the telescope :help

[Yash-xoxo]

The Two-Step Process

As the maintainer explained, you need to:

1. First create/override the icon definition
2. Then map filetypes to that icon

Solution for TelescopePrompt

Here's how to set a custom icon for TelescopePrompt buffers:

local devicons = require("nvim-web-devicons")

-- Step 1: Define your custom icon
devicons.set_icon {
  ["telescope"] = {
    icon = "🔭",  -- or any icon you prefer
    color = "#519aba",
    cterm_color = "74",
    name = "Telescope"
  }
}

-- Step 2: Map the filetype to your icon
devicons.set_icon_by_filetype({ 
  TelescopePrompt = "telescope"
})

Why set_icon_by_filetype wasn't working

The issue is that set_icon_by_filetype expects the value to be an existing icon name, not a new icon definition.

-- ❌ This doesn't work - "bmp" is not a defined icon
devicons.set_icon_by_filetype({ toml = "bmp" })

-- ✅ This works - "toml" is an existing icon
devicons.set_icon_by_filetype({ mytoml = "toml" })

Complete Working Example

local devicons = require("nvim-web-devicons")

devicons.setup({
  -- Define custom icons via extension first
  override_by_extension = {
    ["telescope"] = {
      icon = "🔭",
      color = "#519aba",
      name = "Telescope",
    },
  },
})

-- Then map filetypes to those icons
devicons.set_icon_by_filetype({ 
  TelescopePrompt = "telescope",
  TelescopeResults = "telescope",
})

Alternative: All in setup()

If you want everything in one place:

require("nvim-web-devicons").setup({
  override_by_extension = {
    ["telescope"] = {
      icon = "🔭",
      color = "#519aba",
      name = "Telescope",
    },
  },
  override_by_filename = {
    ["TelescopePrompt"] = {
      icon = "🔭",
      color = "#519aba",
      name = "Telescope",
    },
  },
})

Debugging Tips

Check if your filetype is being recognized:

:set filetype?

For Telescope buffers, you might see TelescopePrompt, TelescopeResults, etc.

Verify your icon is registered:

:lua print(vim.inspect(require("nvim-web-devicons").get_icon_by_filetype("TelescopePrompt")))

Understanding the API

• set_icon / override_by_extension: Creates new icon definitions
• set_icon_by_filetype: Maps filetypes → existing icon names (not definitions)
• override_by_filename: Direct mapping for specific buffer names

For Your Norg Example

local devicons = require("nvim-web-devicons")

-- Define the icon
devicons.set_icon {
  ["norg_custom"] = {
    icon = "y",
    color = "#519aba",
    name = "Norg",
  }
}

-- Map the filetype
devicons.set_icon_by_filetype({ norg = "norg_custom" })

Hope this clears up the distinction! The key insight is that set_icon_by_filetype is a reference system, not a definition system.

[alex-courtis]

Thanks for the great writeup @Yash-xoxo and for explaining override_by_extension