Split schema function into describeSchema and describeTable

src/sqlite.js

@@ -39,14 +39,66 @@ export class SQLiteDatabaseClient {
       element("tbody", rows.map(r => element("tr", columns.map(c => element("td", [text(r[c])])))))
     ]);
   }
+  async describeSchema() {
+    return await this.query(`SELECT name FROM sqlite_master WHERE type = 'table'`);
+  }
+  async describeTable(specifier) {
+    const rows = await this.query(`SELECT * FROM pragma_table_info(?)`, [specifier]);
+    if (!rows.length) throw new Error(`table not found: ${specifier}`);
+    return rows.map(({name, type, notnull}) => {
+      const t = sqliteType(type);
+      return {
+        name,
+        type: notnull || t === "null" ? t : [t, "null"],
+        databaseType: type
+      };
+    });
+  }
   async sql(strings, ...args) {
     return this.query(strings.join("?"), args);
   }
 }
+
 Object.defineProperty(SQLiteDatabaseClient.prototype, "dialect", {
   value: "sqlite"
 });
 
+// https://www.sqlite.org/datatype3.html
+function sqliteType(type) {
+  switch (type) {
+    case "NULL":
+      return "null";
+    case "INT":
+    case "INTEGER":
+    case "TINYINT":
+    case "SMALLINT":
+    case "MEDIUMINT":
+    case "BIGINT":
+    case "UNSIGNED BIG INT":
+    case "INT2":
+    case "INT8":
+      return "integer";
+    case "TEXT":
+    case "CLOB":
+      return "string";
+    case "REAL":
+    case "DOUBLE":
+    case "DOUBLE PRECISION":
+    case "FLOAT":
+    case "NUMERIC":
+      return "number";
+    case "BLOB":
+      return "buffer";
+    case "DATE":
+    case "DATETIME":
+      return "string"; // TODO convert strings to Date instances
+    default:
+      return /^(?:(?:(?:VARYING|NATIVE) )?CHARACTER|(?:N|VAR|NVAR)CHAR)\(/.test(type) ? "string"
+        : /^(?:DECIMAL|NUMERIC)\(/.test(type) ? "number"
+        : "other";
+  }
+}
+
 function load(source) {
   return typeof source === "string" ? fetch(source).then(load)
     : source instanceof Response || source instanceof Blob ? source.arrayBuffer().then(load)