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#pragma once
#include <Core/Block.h>
#include <Processors/Formats/IRowInputFormat.h>
#include <Processors/Formats/ISchemaReader.h>
#include <Formats/FormatSettings.h>
#include <Formats/SchemaInferenceUtils.h>
#include <Common/HashTable/HashMap.h>
namespace DB
{
class ReadBuffer;
/** A stream for reading data in JSON format, where each row is represented by a separate JSON object.
* Objects can be separated by line feed, other whitespace characters in any number and possibly a comma.
* Fields can be listed in any order (including, in different lines there may be different order),
* and some fields may be missing.
*/
class JSONEachRowRowInputFormat : public IRowInputFormat
{
public:
JSONEachRowRowInputFormat(
ReadBuffer & in_,
const Block & header_,
Params params_,
const FormatSettings & format_settings_,
bool yield_strings_);
String getName() const override { return "JSONEachRowRowInputFormat"; }
void resetParser() override;
private:
void readPrefix() override;
void readSuffix() override;
bool readRow(MutableColumns & columns, RowReadExtension & ext) override;
bool allowSyncAfterError() const override { return true; }
void syncAfterError() override;
size_t countRows(size_t max_block_size) override;
bool supportsCountRows() const override { return true; }
const String & columnName(size_t i) const;
size_t columnIndex(StringRef name, size_t key_index);
bool advanceToNextKey(size_t key_index);
void skipUnknownField(StringRef name_ref);
StringRef readColumnName(ReadBuffer & buf);
void readField(size_t index, MutableColumns & columns);
void readJSONObject(MutableColumns & columns);
void readNestedData(const String & name, MutableColumns & columns);
virtual void readRowStart(MutableColumns &) {}
virtual void skipRowStart() {}
/// Buffer for the read from the stream field name. Used when you have to copy it.
/// Also, if processing of Nested data is in progress, it holds the common prefix
/// of the nested column names (so that appending the field name to it produces
/// the full column name)
String current_column_name;
/// If processing Nested data, holds the length of the common prefix
/// of the names of related nested columns. For example, for a table
/// created as follows
/// CREATE TABLE t (n Nested (i Int32, s String))
/// the nested column names are 'n.i' and 'n.s' and the nested prefix is 'n.'
size_t nested_prefix_length = 0;
/// These sets may be different, because if null_as_default=1 read_columns[i] will be false and seen_columns[i] will be true
/// for row like {..., "non-nullable column name" : null, ...}
/// Hash table match `field name -> position in the block`. NOTE You can use perfect hash map.
Block::NameMap name_map;
/// Cached search results for previous row (keyed as index in JSON object) - used as a hint.
std::vector<Block::NameMap::const_iterator> prev_positions;
bool yield_strings;
protected:
virtual bool checkEndOfData(bool is_first_row);
const FormatSettings format_settings;
/// Set of columns for which the values were read. The rest will be filled with default values.
std::vector<UInt8> read_columns;
/// Set of columns which already met in row. Exception is thrown if there are more than one column with the same name.
std::vector<UInt8> seen_columns;
/// This flag is needed to know if data is in square brackets.
bool data_in_square_brackets = false;
bool allow_new_rows = true;
};
class JSONEachRowSchemaReader : public IRowWithNamesSchemaReader
{
public:
JSONEachRowSchemaReader(ReadBuffer & in_, const FormatSettings & format_settings_);
private:
NamesAndTypesList readRowAndGetNamesAndDataTypes(bool & eof) override;
void transformTypesIfNeeded(DataTypePtr & type, DataTypePtr & new_type) override;
void transformFinalTypeIfNeeded(DataTypePtr & type) override;
bool first_row = true;
bool data_in_square_brackets = false;
JSONInferenceInfo inference_info;
};
}
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