Merge pull request #10401 from maiadegraaf/c_api_additions

[C-API] Add duckdb_appender_column_type

src/include/duckdb.h

@@ -2483,6 +2483,25 @@ Note that the object must be destroyed with `duckdb_appender_destroy`.
 DUCKDB_API duckdb_state duckdb_appender_create(duckdb_connection connection, const char *schema, const char *table,
                                                duckdb_appender *out_appender);
 
+/*!
+Returns the number of columns in the table that belongs to the appender.
+
+* appender The appender to get the column count from.
+* returns: The number of columns in the table.
+*/
+DUCKDB_API idx_t duckdb_appender_column_count(duckdb_appender appender);
+
+/*!
+Returns the type of the column at the specified index.
+
+Note: The resulting type should be destroyed with `duckdb_destroy_logical_type`.
+
+* appender The appender to get the column type from.
+* col_idx The index of the column to get the type of.
+* returns: The duckdb_logical_type of the column.
+*/
+DUCKDB_API duckdb_logical_type duckdb_appender_column_type(duckdb_appender appender, idx_t col_idx);
+
 /*!
 Returns the error message associated with the given appender.
 If the appender has no error message, this returns `nullptr` instead.

src/main/appender.cpp

@@ -327,8 +327,15 @@ void BaseAppender::AppendValue(const Value &value) {
 }
 
 void BaseAppender::AppendDataChunk(DataChunk &chunk) {
-	if (chunk.GetTypes() != types) {
-		throw InvalidInputException("Type mismatch in Append DataChunk and the types required for appender");
+	auto chunk_types = chunk.GetTypes();
+	if (chunk_types != types) {
+		for (idx_t i = 0; i < chunk.ColumnCount(); i++) {
+			if (chunk.data[i].GetType() != types[i]) {
+				throw InvalidInputException("Type mismatch in Append DataChunk and the types required for appender, "
+				                            "expected %s but got %s for column %d",
+				                            types[i].ToString(), chunk.data[i].GetType().ToString(), i + 1);
+			}
+		}
 	}
 	collection->Append(chunk);
 	if (collection->Count() >= FLUSH_COUNT) {

src/main/capi/appender-c.cpp

@@ -212,6 +212,32 @@ duckdb_state duckdb_appender_close(duckdb_appender appender) {
 	return duckdb_appender_run_function(appender, [&](Appender &appender) { appender.Close(); });
 }
 
+idx_t duckdb_appender_column_count(duckdb_appender appender) {
+	if (!appender) {
+		return 0;
+	}
+
+	auto wrapper = reinterpret_cast<AppenderWrapper *>(appender);
+	if (!wrapper->appender) {
+		return 0;
+	}
+
+	return wrapper->appender->GetTypes().size();
+}
+
+duckdb_logical_type duckdb_appender_column_type(duckdb_appender appender, idx_t col_idx) {
+	if (!appender || col_idx >= duckdb_appender_column_count(appender)) {
+		return nullptr;
+	}
+
+	auto wrapper = reinterpret_cast<AppenderWrapper *>(appender);
+	if (!wrapper->appender) {
+		return nullptr;
+	}
+
+	return reinterpret_cast<duckdb_logical_type>(new duckdb::LogicalType(wrapper->appender->GetTypes()[col_idx]));
+}
+
 duckdb_state duckdb_append_data_chunk(duckdb_appender appender, duckdb_data_chunk chunk) {
 	if (!chunk) {
 		return DuckDBError;

test/api/capi/test_capi_data_chunk.cpp

@@ -127,11 +127,21 @@ TEST_CASE("Test DataChunk C API", "[capi]") {
 	REQUIRE(duckdb_data_chunk_get_size(nullptr) == 0);
 
 	// use the appender to insert a value using the data chunk API
-
 	duckdb_appender appender;
 	status = duckdb_appender_create(tester.connection, nullptr, "test", &appender);
 	REQUIRE(status == DuckDBSuccess);
 
+	// get the column types from the appender
+	REQUIRE(duckdb_appender_column_count(appender) == 2);
+
+	auto appender_first_type = duckdb_appender_column_type(appender, 0);
+	REQUIRE(duckdb_get_type_id(appender_first_type) == DUCKDB_TYPE_BIGINT);
+	duckdb_destroy_logical_type(&appender_first_type);
+
+	auto appender_second_type = duckdb_appender_column_type(appender, 1);
+	REQUIRE(duckdb_get_type_id(appender_second_type) == DUCKDB_TYPE_SMALLINT);
+	duckdb_destroy_logical_type(&appender_second_type);
+
 	// append standard primitive values
 	auto col1_ptr = (int64_t *)duckdb_vector_get_data(duckdb_data_chunk_get_vector(data_chunk, 0));
 	*col1_ptr = 42;
@@ -193,6 +203,46 @@ TEST_CASE("Test DataChunk C API", "[capi]") {
 	duckdb_destroy_logical_type(&types[1]);
 }
 
+TEST_CASE("Test DataChunk appending incorrect types in C API", "[capi]") {
+	CAPITester tester;
+	duckdb::unique_ptr<CAPIResult> result;
+	duckdb_state status;
+
+	REQUIRE(tester.OpenDatabase(nullptr));
+
+	REQUIRE(duckdb_vector_size() == STANDARD_VECTOR_SIZE);
+
+	tester.Query("CREATE TABLE test(i BIGINT, j SMALLINT)");
+
+	duckdb_logical_type types[2];
+	types[0] = duckdb_create_logical_type(DUCKDB_TYPE_BIGINT);
+	types[1] = duckdb_create_logical_type(DUCKDB_TYPE_BOOLEAN);
+
+	auto data_chunk = duckdb_create_data_chunk(types, 2);
+	REQUIRE(data_chunk);
+
+	auto col1_ptr = (int64_t *)duckdb_vector_get_data(duckdb_data_chunk_get_vector(data_chunk, 0));
+	*col1_ptr = 42;
+	auto col2_ptr = (bool *)duckdb_vector_get_data(duckdb_data_chunk_get_vector(data_chunk, 1));
+	*col2_ptr = false;
+
+	duckdb_appender appender;
+	status = duckdb_appender_create(tester.connection, nullptr, "test", &appender);
+	REQUIRE(status == DuckDBSuccess);
+
+	REQUIRE(duckdb_append_data_chunk(appender, data_chunk) == DuckDBError);
+
+	auto error = duckdb_appender_error(appender);
+	REQUIRE(duckdb::StringUtil::Contains(error, "expected SMALLINT but got BOOLEAN for column 2"));
+
+	duckdb_appender_destroy(&appender);
+
+	duckdb_destroy_data_chunk(&data_chunk);
+
+	duckdb_destroy_logical_type(&types[0]);
+	duckdb_destroy_logical_type(&types[1]);
+}
+
 TEST_CASE("Test DataChunk varchar result fetch in C API", "[capi]") {
 	if (duckdb_vector_size() < 64) {
 		return;