fix(plugin-duckdb): render VARIANT columns as text

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Traditional Chinese (繁體中文) language in Settings > General with full UI translation
 
+### Fixed
+
+- DuckDB VARIANT columns now show their value as text instead of an empty cell.
+
 ## [0.51.1] - 2026-06-16
 
 ### Added

Plugins/DuckDBDriverPlugin/DuckDBConnection.swift

@@ -91,7 +91,7 @@ actor DuckDBConnectionActor {
         }
 
         var raw = Self.extractResult(from: &result, startTime: startTime)
-        Self.patchTzColumns(&raw, query: query, connection: conn)
+        Self.patchCastedColumns(&raw, query: query, connection: conn)
         return raw
     }
 
@@ -163,7 +163,7 @@ actor DuckDBConnectionActor {
         }
 
         var raw = Self.extractResult(from: &result, startTime: startTime)
-        Self.patchTzColumns(&raw, query: query, connection: conn)
+        Self.patchCastedColumns(&raw, query: query, connection: conn)
         return raw
     }
 
@@ -204,7 +204,7 @@ actor DuckDBConnectionActor {
             columnTypeNames.append(Self.typeName(for: colType))
         }
 
-        if columnTypes.contains(where: Self.isUnrenderable) {
+        if columnTypes.contains(where: Self.requiresTextCast) {
             duckdb_destroy_result(&result)
             try Self.streamWrappedQuery(
                 query: query,
@@ -235,7 +235,7 @@ actor DuckDBConnectionActor {
         continuation: AsyncThrowingStream<PluginStreamElement, Error>.Continuation
     ) throws {
         let castExprs = columns.enumerated().map { i, name in
-            castExpression(for: columnTypes[i], column: name)
+            projection(for: columnTypes[i], column: name)
         }
         let wrappedQuery = buildWrappedQuery(originalQuery: query, castExprs: castExprs)
 
@@ -484,16 +484,16 @@ actor DuckDBConnectionActor {
         }
     }
 
-    static func patchTzColumns(
+    static func patchCastedColumns(
         _ raw: inout DuckDBRawResult, query: String, connection: duckdb_connection
     ) {
         let patchedColIndices = raw.columnTypes.enumerated().compactMap { idx, type in
-            isUnrenderable(type) ? idx : nil
+            requiresTextCast(type) ? idx : nil
         }
         guard !patchedColIndices.isEmpty, !raw.rows.isEmpty else { return }
 
         let castExprs = raw.columns.enumerated().map { i, name in
-            castExpression(for: raw.columnTypes[i], column: name)
+            projection(for: raw.columnTypes[i], column: name)
         }
         let wrappedQuery = buildWrappedQuery(originalQuery: query, castExprs: castExprs)
 
@@ -514,25 +514,36 @@ actor DuckDBConnectionActor {
         }
     }
 
-    static func isUnrenderable(_ type: duckdb_type) -> Bool {
+    static func isNativelyRenderable(_ type: duckdb_type) -> Bool {
         switch type {
-        case DUCKDB_TYPE_TIMESTAMP_TZ, DUCKDB_TYPE_TIME_TZ, DUCKDB_TYPE_GEOMETRY:
+        case DUCKDB_TYPE_BOOLEAN,
+             DUCKDB_TYPE_TINYINT, DUCKDB_TYPE_SMALLINT, DUCKDB_TYPE_INTEGER, DUCKDB_TYPE_BIGINT, DUCKDB_TYPE_HUGEINT,
+             DUCKDB_TYPE_UTINYINT, DUCKDB_TYPE_USMALLINT, DUCKDB_TYPE_UINTEGER, DUCKDB_TYPE_UBIGINT, DUCKDB_TYPE_UHUGEINT,
+             DUCKDB_TYPE_FLOAT, DUCKDB_TYPE_DOUBLE, DUCKDB_TYPE_DECIMAL,
+             DUCKDB_TYPE_VARCHAR, DUCKDB_TYPE_BLOB, DUCKDB_TYPE_UUID, DUCKDB_TYPE_BIT, DUCKDB_TYPE_ENUM,
+             DUCKDB_TYPE_DATE, DUCKDB_TYPE_TIME, DUCKDB_TYPE_TIME_NS, DUCKDB_TYPE_INTERVAL,
+             DUCKDB_TYPE_TIMESTAMP, DUCKDB_TYPE_TIMESTAMP_S, DUCKDB_TYPE_TIMESTAMP_MS, DUCKDB_TYPE_TIMESTAMP_NS,
+             DUCKDB_TYPE_LIST, DUCKDB_TYPE_STRUCT, DUCKDB_TYPE_MAP, DUCKDB_TYPE_ARRAY, DUCKDB_TYPE_UNION:
             return true
         default:
             return false
         }
     }
 
+    static func requiresTextCast(_ type: duckdb_type) -> Bool {
+        !isNativelyRenderable(type)
+    }
+
     static func castExpression(for type: duckdb_type, column: String) -> String {
         let quoted = quoteIdentifier(column)
-        switch type {
-        case DUCKDB_TYPE_GEOMETRY:
+        if type == DUCKDB_TYPE_GEOMETRY {
             return "CASE WHEN \(quoted) IS NULL THEN NULL ELSE ST_AsText(\(quoted)) END AS \(quoted)"
-        case DUCKDB_TYPE_TIMESTAMP_TZ, DUCKDB_TYPE_TIME_TZ:
-            return "CASE WHEN \(quoted) IS NULL THEN NULL ELSE CAST(\(quoted) AS VARCHAR) END AS \(quoted)"
-        default:
-            return quoted
         }
+        return "CASE WHEN \(quoted) IS NULL THEN NULL ELSE CAST(\(quoted) AS VARCHAR) END AS \(quoted)"
+    }
+
+    static func projection(for type: duckdb_type, column: String) -> String {
+        requiresTextCast(type) ? castExpression(for: type, column: column) : quoteIdentifier(column)
     }
 
     static func buildWrappedQuery(originalQuery: String, castExprs: [String]) -> String {

TableProMobile/TableProMobileTests/Drivers/DuckDBDriverTests.swift

@@ -115,6 +115,14 @@ final class DuckDBDriverTests: XCTestCase {
         XCTAssertTrue(value.contains("2024-01-02"), "expected rendered timestamptz, got \(value)")
     }
 
+    func testVariantRendersAsText() async throws {
+        let driver = try XCTUnwrap(driver)
+        let result = try await driver.execute(query: "SELECT {'a': 42, 'b': [1, 2, 3]}::VARIANT AS v")
+        XCTAssertEqual(result.rows.count, 1)
+        let value = try XCTUnwrap(result.rows[0][0])
+        XCTAssertTrue(value.contains("42"), "expected rendered variant text, got \(value)")
+    }
+
     func testCancelWithoutRunningQueryIsSafe() async throws {
         let driver = try XCTUnwrap(driver)
         try await driver.cancelCurrentQuery()

docs/databases/duckdb.mdx

@@ -99,7 +99,7 @@ DuckDB supports a wide range of data types:
 | Numeric | `INTEGER`, `BIGINT`, `HUGEINT`, `DOUBLE`, `FLOAT`, `DECIMAL` |
 | String | `VARCHAR`, `TEXT`, `CHAR` |
 | Date/Time | `DATE`, `TIME`, `TIMESTAMP`, `INTERVAL` |
-| Complex | `LIST`, `MAP`, `STRUCT`, `UNION`, `ENUM` |
+| Complex | `LIST`, `MAP`, `STRUCT`, `UNION`, `ENUM`, `VARIANT` |
 | Other | `BOOLEAN`, `BLOB`, `UUID`, `JSON`, `BIT` |
 
 ## Limitations