Merge pull request #839 from suketa/duckdb_append_error

add DuckDB::Appender#error_message

Author: suketa

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 All notable changes to this project will be documented in this file.
 # Unreleased
+- add 'DuckDB::Appender#error_message'.
+- fix error message when DuckDB::Appender#flush failed.
+
 # 1.1.3.1 - 2024-11-27
 - fix to `DuckDB::Connection#query` with multiple SQL statements. Calling PreparedStatement#destroy after each statement executed.
 - install valgrind in docker development environment.

ext/duckdb/appender.c

@@ -6,6 +6,7 @@ static void deallocate(void *);
 static VALUE allocate(VALUE klass);
 static size_t memsize(const void *p);
 static VALUE appender_initialize(VALUE klass, VALUE con, VALUE schema, VALUE table);
+static VALUE appender_error_message(VALUE self);
 static VALUE appender_begin_row(VALUE self);
 static VALUE appender_end_row(VALUE self);
 static VALUE appender_append_bool(VALUE self, VALUE val);
@@ -34,7 +35,7 @@ static VALUE appender__append_time(VALUE self, VALUE hour, VALUE min, VALUE sec,
 static VALUE appender__append_timestamp(VALUE self, VALUE year, VALUE month, VALUE day, VALUE hour, VALUE min, VALUE sec, VALUE micros);
 static VALUE appender__append_hugeint(VALUE self, VALUE lower, VALUE upper);
 static VALUE appender__append_uhugeint(VALUE self, VALUE lower, VALUE upper);
-static VALUE appender_flush(VALUE self);
+static VALUE appender__flush(VALUE self);
 static VALUE appender_close(VALUE self);
 
 static const rb_data_type_t appender_data_type = {
@@ -82,6 +83,30 @@ static VALUE appender_initialize(VALUE self, VALUE con, VALUE schema, VALUE tabl
     return self;
 }
 
+/* call-seq:
+ *   appender.error_message -> String
+ *
+ * Returns the error message of the appender. If there is no error, then it returns nil.
+ *
+ *   require 'duckdb'
+ *   db = DuckDB::Database.open
+ *   con = db.connect
+ *   con.query('CREATE TABLE users (id INTEGER, name VARCHAR)')
+ *   appender = con.appender('users')
+ *   appender.error_message # => nil
+ */
+static VALUE appender_error_message(VALUE self) {
+    rubyDuckDBAppender *ctx;
+    const char *msg;
+    TypedData_Get_Struct(self, rubyDuckDBAppender, &appender_data_type, ctx);
+
+    msg = duckdb_appender_error(ctx->appender);
+    if (msg == NULL) {
+        return Qnil;
+    }
+    return rb_str_new2(msg);
+}
+
 /* call-seq:
  *   appender.begin_row -> self
  *
@@ -507,32 +532,15 @@ static VALUE appender__append_uhugeint(VALUE self, VALUE lower, VALUE upper) {
     return self;
 }
 
-/* call-seq:
- *   appender.flush -> self
- *
- * Flushes the appender to the table, forcing the cache of the appender to be cleared. If flushing the data triggers a
- * constraint violation or any other error, then all data is invalidated, and this method raises DuckDB::Error.
- *
- *   require 'duckdb'
- *   db = DuckDB::Database.open
- *   con = db.connect
- *   con.query('CREATE TABLE users (id INTEGER, name VARCHAR)')
- *   appender = con.appender('users')
- *   appender
- *     .begin_row
- *     .append_int32(1)
- *     .append_varchar('Alice')
- *     .end_row
- *     .flush
- */
-static VALUE appender_flush(VALUE self) {
+/* :nodoc: */
+static VALUE appender__flush(VALUE self) {
     rubyDuckDBAppender *ctx;
     TypedData_Get_Struct(self, rubyDuckDBAppender, &appender_data_type, ctx);
 
     if (duckdb_appender_flush(ctx->appender) == DuckDBError) {
-        rb_raise(eDuckDBError, "failed to flush");
+        return Qfalse;
     }
-    return self;
+    return Qtrue;
 }
 
 static VALUE appender_close(VALUE self) {
@@ -552,6 +560,7 @@ void rbduckdb_init_duckdb_appender(void) {
     cDuckDBAppender = rb_define_class_under(mDuckDB, "Appender", rb_cObject);
     rb_define_alloc_func(cDuckDBAppender, allocate);
     rb_define_method(cDuckDBAppender, "initialize", appender_initialize, 3);
+    rb_define_method(cDuckDBAppender, "error_message", appender_error_message, 0);
     rb_define_method(cDuckDBAppender, "begin_row", appender_begin_row, 0);
     rb_define_method(cDuckDBAppender, "end_row", appender_end_row, 0);
     rb_define_method(cDuckDBAppender, "append_bool", appender_append_bool, 1);
@@ -569,13 +578,13 @@ void rbduckdb_init_duckdb_appender(void) {
     rb_define_method(cDuckDBAppender, "append_varchar_length", appender_append_varchar_length, 2);
     rb_define_method(cDuckDBAppender, "append_blob", appender_append_blob, 1);
     rb_define_method(cDuckDBAppender, "append_null", appender_append_null, 0);
-    rb_define_method(cDuckDBAppender, "flush", appender_flush, 0);
     rb_define_method(cDuckDBAppender, "close", appender_close, 0);
 
 #ifdef HAVE_DUCKDB_H_GE_V1_1_0
     rb_define_method(cDuckDBAppender, "append_default", appender_append_default, 0);
 #endif
 
+    rb_define_private_method(cDuckDBAppender, "_flush", appender__flush, 0);
     rb_define_private_method(cDuckDBAppender, "_append_date", appender__append_date, 3);
     rb_define_private_method(cDuckDBAppender, "_append_interval", appender__append_interval, 3);
     rb_define_private_method(cDuckDBAppender, "_append_time", appender__append_time, 4);

lib/duckdb/appender.rb

@@ -23,6 +23,30 @@ class Appender
     private_constant :RANGE_INT16, :RANGE_INT32, :RANGE_INT64
     # :startdoc:
 
+    # :call-seq:
+    #  flush -> self
+    #
+    # Flushes the appender to the table, forcing the cache of the appender to be cleared.
+    # If flushing the data triggers a constraint violation or any other error, then all
+    # data is invalidated, and this method raises DuckDB::Error.
+    #
+    #   require 'duckdb'
+    #   db = DuckDB::Database.open
+    #   con = db.connect
+    #   con.query('CREATE TABLE users (id INTEGER, name VARCHAR)')
+    #   appender = con.appender('users')
+    #   appender
+    #     .begin_row
+    #     .append_int32(1)
+    #     .append_varchar('Alice')
+    #     .end_row
+    #     .flush
+    def flush
+      return self if _flush
+
+      raise_appender_error('failed to flush')
+    end
+
     # appends huge int value.
     #
     #   require 'duckdb'
@@ -196,6 +220,11 @@ def append_row(*args)
 
     private
 
+    def raise_appender_error(default_message) # :nodoc:
+      message = error_message
+      raise DuckDB::Error, message || default_message
+    end
+
     def blob?(value) # :nodoc:
       value.instance_of?(DuckDB::Blob) || value.encoding == Encoding::BINARY
     end

test/duckdb_test/appender_test.rb

@@ -88,6 +88,25 @@ def assert_duckdb_appender(expected, type, &block)
       teardown
     end
 
+    def test_flush
+      appender = create_appender('col BOOLEAN')
+      appender
+        .begin_row
+        .append_bool(true)
+        .end_row
+      assert_equal(appender.__id__, appender.flush.__id__)
+    end
+
+    def test_flush_with_exception
+      appender = create_appender('col BOOLEAN NOT NULL')
+      appender
+        .begin_row
+        .append_null
+        .end_row
+      exception = assert_raises(DuckDB::Error) { appender.flush }
+      assert_match(/NOT NULL constraint failed/, exception.message)
+    end
+
     def test_append_bool
       assert_duckdb_appender(true, 'BOOLEAN') { |a| a.append_bool(true) }
       assert_duckdb_appender(false, 'BOOLEAN') { |a| a.append_bool(false) }