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Editor Setup

smelt provides a Language Server Protocol (LSP) implementation for real-time feedback in your editor.

See it in action

For visual demos of every LSP feature -- diagnostics, go-to-definition, hover, completions, references, rename, and code actions -- see Editor Features.

VSCode

Install the smelt extension from the VS Marketplace.

The extension automatically discovers the smelt-lsp binary using this priority chain:

  1. User config — smelt.serverPath setting in VSCode
  2. Python environment — if you installed via pip install smelt-sql
  3. PATH lookup — if smelt-lsp is on your system PATH
  4. Cargo fallback — cargo run -p smelt-lsp (development only, requires Cargo.toml)

Features

  • Syntax highlighting for SQL + smelt extensions
  • Real-time diagnostics (see Diagnostics below)
  • Go-to-definition (see Go-to-definition below)
  • Hover information with type details
  • Column completions with table alias support

Settings

Setting Description
smelt.serverPath Explicit path to smelt-lsp binary
smelt.trace.server LSP trace level (off, messages, verbose)

Go-to-definition

The LSP supports go-to-definition for multiple targets:

Cursor position Jumps to
smelt.model_name The referenced model's SQL file
smelt.sources.schema.table The per-entity source .yml file
CTE name in FROM/JOIN The CTE definition in the WITH clause
Table alias (e.g., t in t.column) Where the alias is defined
Column reference The column's definition in the upstream SELECT, CTE, or source .yml

Column go-to-definition traces through SELECT * wildcards to find the original definition. If a column name is ambiguous (unqualified with multiple possible sources), multiple locations are returned.

Diagnostics

The LSP reports errors and warnings in real time as you edit:

  • Parse errors -- Syntax mistakes in SQL
  • Undefined refs -- smelt.model where model does not exist
  • Undeclared columns -- References to columns not present in upstream model schemas or source .yml declarations
  • Unsupported syntax -- Features like PIVOT/UNPIVOT that smelt does not support

Undeclared column diagnostics catch typos and schema drift at edit time, before you run anything. For example:

SELECT visitor_id FROM smelt.sources.raw.sessions
-- Error: Column 'visitor_id' not found in source 'raw.sessions'

Tip

Column diagnostics require that your per-entity source .yml files declare column names (types are optional). Without column declarations, the LSP cannot validate column references against external sources.

Other editors

Any editor with LSP support can use smelt-lsp. Start the server and configure your editor's LSP client to connect to it:

smelt-lsp

The server communicates over stdin/stdout using the standard LSP protocol.