Editor completions

TypeScript checks a statement and shows its errors and row type in the editor, but it does not suggest what to type inside the string. The TypeSQL extension for VS Code does:

sql("SELECT * FROM |");          // users, posts, active_users, auth, …
sql("SELECT u.| FROM users u");  // id: int4, email: text, display_name: text | null

The names come from the DB type of the sql you call, so they follow your schema as you edit it, unsaved changes included. The extension adds suggestions only: errors, hovers and row types are TypeScript's, as without it.

The extension is an optional companion. TypeSQL needs only TypeScript, so skip it unless you want completions.

Setup

1. Install the TypeSQL extension from the Visual Studio Marketplace or Open VSX, and the TypeScript 7 extension (TypeScriptTeam.native-preview) next to it.

2. Have @typesql/core 0.4.0 or later in the project, directly or through an adapter (@typesql/pg, @typesql/postgres, @typesql/kysely, @typesql/drizzle, @typesql/prisma). The extension loads the project's own copy, so suggestions follow the version the project checks with.

3. Run the language server on TypeScript 7.1 or later. Version 1.0 of the TypeScript 7 extension bundles TypeScript 7.0, whose API cannot read the editor's program, and its version picker does not list a workspace typescript package. Either add TypeScript 7.1 to the project and point the extension at it in .vscode/settings.json:

   npm install -D typescript@7.1.0-beta

   {
     "js/ts.experimental.useTsgo": true,
     "js/ts.tsdk.path": "node_modules/typescript"
   }

   and choose Allow when VS Code asks whether to use it (once per workspace); or install the TypeScript 7 Nightly extension, which the TypeScript 7 extension then uses. The TypeScript 7 output channel's first line shows which server started.

Turn suggestions off with "typesql.completions.enable": false.

What it suggests

Before the cursor	Suggestions
FROM, JOIN, INTO, UPDATE, TABLE, USING, a comma in a FROM list	tables and views (those the statement already uses first), CTEs, schemas
schema.	the relations of that schema; pg_catalog. for the PgCatalog slice
alias. or table.	the columns of that FROM item, with their types
SELECT, WHERE, ON, AND, BY, RETURNING, an operator, (, a comma in a list	the columns of every FROM item in scope, then their aliases
INSERT INTO t (, UPDATE t SET, ON CONFLICT (	the columns of t

Aliases follow scope: a subquery sees its own FROM items first, then the outer query's. Subqueries and CTEs offer the names of their output columns. Names that Postgres would fold or read as a keyword are inserted in double quotes ("UserAccounts", "order"). Suggestions work in sql(), in tx() inside sql.transaction(), in sql.fragment() and sql.as(), in template literals across lines, and between ${sql.param()} values. There are none inside string literals, comments and quoted identifiers.

How it works

The TypeScript 7 extension runs the TypeScript language server. When it answers a completion request, the TypeSQL extension opens an API session on that same server (no second TypeScript process), finds the sql() call at the cursor, reads relations and columns from its DB type with the checker, and reads the text before the cursor with a small scanner: keywords, FROM items, aliases and CTEs. It never evaluates the statement's types, so a request typically takes 10 to 30 ms. A request that fails or takes longer than 150 ms adds nothing.

TypeScript itself offers one item inside a valid statement: the statement text, which would replace the whole string. With a TypeScript 7 extension that lets other extensions change its responses (TypeScript 7.1's extension API), TypeSQL drops that item. Version 1.0 of the TypeScript 7 extension does not, so there TypeSQL adds its own suggestion provider and VS Code shows both lists, the statement text included. That version also does not say which TypeScript its server runs, so TypeSQL tries the TypeScript packages it can find (the js/ts.tsdk.path package, the project's, the nightly extension's) and keeps the one the server understands.

Troubleshooting

• The TypeSQL output channel logs which @typesql/core and which TypeScript API client the extension loaded, slow requests and errors, and says so when the language server runs TypeScript 7.0 or when no client matches it.
• Suggestions you see without the extension, such as words from open files (abc icon), come from VS Code; "editor.wordBasedSuggestions": "off" turns those off.
• After installing or upgrading @typesql/core or typescript, run TypeScript: Restart TS Server so the extension looks them up again.
• The TypeScript 7 extension's API is new in TypeScript 7.1 and may still change before 7.1 is final.