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Fix parquet-reader outputting invalid json #72

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Fix parquet-reader outputting invalid json #72

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e4efa2d
Fix parquet-reader outputting invalid json
al13n321 Sep 26, 2025
c4a1ea2
Escape strings
al13n321 Sep 26, 2025
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30 changes: 18 additions & 12 deletions cpp/src/parquet/printer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -281,21 +281,27 @@ void ParquetFilePrinter::JSONPrint(std::ostream& stream, std::list<int> selected
<< "\"StatsSet\": ";
if (column_chunk->is_stats_set()) {
stream << "\"True\", \"Stats\": {";
bool comma = false;
if (stats->HasNullCount()) {
stream << "\"NumNulls\": \"" << stats->null_count();
comma = true;
stream << "\"NumNulls\": \"" << stats->null_count() << "\"";
}
if (stats->HasDistinctCount()) {
stream << "\", "
<< "\"DistinctValues\": \"" << stats->distinct_count();
if (comma)
stream << ", ";
comma = true;
stream << "\"DistinctValues\": \"" << stats->distinct_count() << "\"";
}
if (stats->HasMinMax()) {
if (comma)
stream << ", ";
comma = true;
std::string min = stats->EncodeMin(), max = stats->EncodeMax();
stream << "\", "
<< "\"Max\": \"" << FormatStatValue(descr->physical_type(), max)
stream << "\"Max\": \"" << FormatStatValue(descr->physical_type(), max)
<< "\", "
<< "\"Min\": \"" << FormatStatValue(descr->physical_type(), min);
<< "\"Min\": \"" << FormatStatValue(descr->physical_type(), min) << "\"";
}
stream << "\" },";
stream << " },";
} else {
stream << "\"False\",";
}
Expand All @@ -312,11 +318,11 @@ void ParquetFilePrinter::JSONPrint(std::ostream& stream, std::list<int> selected
}
stream << "\", "
<< "\"UncompressedSize\": \"" << column_chunk->total_uncompressed_size()
<< "\", \"CompressedSize\": \"" << column_chunk->total_compressed_size();
<< "\", \"CompressedSize\": \"" << column_chunk->total_compressed_size() << "\"";

if (column_chunk->bloom_filter_offset()) {
// Output BloomFilter {offset, length}
stream << "\", BloomFilter {"
stream << ", \"BloomFilter\": {"
<< "\"offset\": \"" << column_chunk->bloom_filter_offset().value();
if (column_chunk->bloom_filter_length()) {
stream << "\", \"length\": \"" << column_chunk->bloom_filter_length().value();
Expand All @@ -327,7 +333,7 @@ void ParquetFilePrinter::JSONPrint(std::ostream& stream, std::list<int> selected
if (column_chunk->GetColumnIndexLocation()) {
auto location = column_chunk->GetColumnIndexLocation().value();
// Output ColumnIndex {offset, length}
stream << "\", ColumnIndex {"
stream << ", \"ColumnIndex\": {"
<< "\"offset\": \"" << location.offset;
stream << "\", \"length\": \"" << location.length;
stream << "\"}";
Expand All @@ -336,14 +342,14 @@ void ParquetFilePrinter::JSONPrint(std::ostream& stream, std::list<int> selected
if (column_chunk->GetOffsetIndexLocation()) {
auto location = column_chunk->GetOffsetIndexLocation().value();
// Output OffsetIndex {offset, length}
stream << "\", OffsetIndex {"
stream << ", \"OffsetIndex\": {"
<< "\"offset\": \"" << location.offset;
stream << "\", \"length\": \"" << location.length;
stream << "\"}";
}

// end of a ColumnChunk
stream << "\" }";
stream << " }";
c1++;
if (c1 != static_cast<int>(selected_columns.size())) {
stream << ",\n";
Expand Down
22 changes: 16 additions & 6 deletions cpp/src/parquet/types.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -115,12 +115,22 @@ std::string FormatStatValue(Type::type parquet_type, ::std::string_view val) {
result << i32_val[0] << " " << i32_val[1] << " " << i32_val[2];
break;
}
case Type::BYTE_ARRAY: {
return std::string(val);
}
case Type::FIXED_LEN_BYTE_ARRAY: {
return std::string(val);
}
case Type::BYTE_ARRAY:
case Type::FIXED_LEN_BYTE_ARRAY:
// Escape byte arrays to be usable in json strings.
for (char c : val) {
if (c == '\\' || c == '"')
result << '\\' << c;
else if (c >= 32 && c <= 126)
result << c;
else
// What to do if the byte array is not valid utf8?
// There doesn't seem to be a standard way to reversibly convert byte strings to valid utf8 while keeping simple ascii readable.
// For now we'll just output invalid utf8, which json parsers may be ok with. Idk if that's the best option.
result << c;
// result << "�";
}
break;
case Type::UNDEFINED:
default:
break;
Expand Down
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