ClickHouse/dbms/Interpreters/convertFieldToType.cpp

#include <Interpreters/convertFieldToType.h>

#include <IO/ReadBufferFromString.h>
#include <IO/ReadHelpers.h>

#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeTuple.h>
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/DataTypesDecimal.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/DataTypeFixedString.h>
#include <DataTypes/DataTypeDate.h>
#include <DataTypes/DataTypeDateTime.h>
#include <DataTypes/DataTypeDateTime64.h>
#include <DataTypes/DataTypeEnum.h>
#include <DataTypes/DataTypeNullable.h>

#include <Core/AccurateComparison.h>
#include <Common/FieldVisitors.h>
#include <Common/typeid_cast.h>
#include <Common/NaNUtils.h>
#include <DataTypes/DataTypeUUID.h>
#include <DataTypes/DataTypeLowCardinality.h>

#include <common/DateLUT.h>
#include <DataTypes/DataTypeAggregateFunction.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int ARGUMENT_OUT_OF_BOUND;
    extern const int LOGICAL_ERROR;
    extern const int TYPE_MISMATCH;
    extern const int TOO_LARGE_STRING_SIZE;
}


/** Checking for a `Field from` of `From` type falls to a range of values of type `To`.
  * `From` and `To` - numeric types. They can be floating-point types.
  * `From` is one of UInt64, Int64, Float64,
  *  whereas `To` can also be 8, 16, 32 bit.
  *
  * If falls into a range, then `from` is converted to the `Field` closest to the `To` type.
  * If not, return Field(Null).
  */

namespace
{

template <typename From, typename To>
static Field convertNumericTypeImpl(const Field & from)
{
    To result;
    if (!accurate::convertNumeric(from.get<From>(), result))
        return {};
    return result;
}

template <typename To>
static Field convertNumericType(const Field & from, const IDataType & type)
{
    if (from.getType() == Field::Types::UInt64)
        return convertNumericTypeImpl<UInt64, To>(from);
    if (from.getType() == Field::Types::Int64)
        return convertNumericTypeImpl<Int64, To>(from);
    if (from.getType() == Field::Types::Float64)
        return convertNumericTypeImpl<Float64, To>(from);

    throw Exception("Type mismatch in IN or VALUES section. Expected: " + type.getName() + ". Got: "
        + Field::Types::toString(from.getType()), ErrorCodes::TYPE_MISMATCH);
}


template <typename From, typename T>
static Field convertIntToDecimalType(const Field & from, const DataTypeDecimal<T> & type)
{
    From value = from.get<From>();
    if (!type.canStoreWhole(value))
        throw Exception("Number is too much to place in " + type.getName(), ErrorCodes::ARGUMENT_OUT_OF_BOUND);

    T scaled_value = type.getScaleMultiplier() * value;
    return DecimalField<T>(scaled_value, type.getScale());
}


template <typename T>
static Field convertStringToDecimalType(const Field & from, const DataTypeDecimal<T> & type)
{
    const String & str_value = from.get<String>();
    T value = type.parseFromString(str_value);
    return DecimalField<T>(value, type.getScale());
}

template <typename From, typename T>
static Field convertDecimalToDecimalType(const Field & from, const DataTypeDecimal<T> & type)
{
    auto field = from.get<DecimalField<From>>();
    T value = convertDecimals<DataTypeDecimal<From>, DataTypeDecimal<T>>(field.getValue(), field.getScale(), type.getScale());
    return DecimalField<T>(value, type.getScale());
}

template <typename To>
static Field convertDecimalType(const Field & from, const To & type)
{
    if (from.getType() == Field::Types::UInt64)
        return convertIntToDecimalType<UInt64>(from, type);
    if (from.getType() == Field::Types::Int64)
        return convertIntToDecimalType<Int64>(from, type);
    if (from.getType() == Field::Types::String)
        return convertStringToDecimalType(from, type);

    if (from.getType() == Field::Types::Decimal32)
        return convertDecimalToDecimalType<Decimal32>(from, type);
    if (from.getType() == Field::Types::Decimal64)
        return convertDecimalToDecimalType<Decimal64>(from, type);
    if (from.getType() == Field::Types::Decimal128)
        return convertDecimalToDecimalType<Decimal128>(from, type);

    throw Exception("Type mismatch in IN or VALUES section. Expected: " + type.getName() + ". Got: "
        + Field::Types::toString(from.getType()), ErrorCodes::TYPE_MISMATCH);
}


DayNum stringToDate(const String & s)
{
    ReadBufferFromString in(s);
    DayNum date{};

    readDateText(date, in);
    if (!in.eof())
        throw Exception("String is too long for Date: " + s, ErrorCodes::TOO_LARGE_STRING_SIZE);

    return date;
}

UInt64 stringToDateTime(const String & s)
{
    ReadBufferFromString in(s);
    time_t date_time{};

    readDateTimeText(date_time, in);
    if (!in.eof())
        throw Exception("String is too long for DateTime: " + s, ErrorCodes::TOO_LARGE_STRING_SIZE);

    return UInt64(date_time);
}

DateTime64::NativeType stringToDateTime64(const String & s, UInt32 scale)
{
    ReadBufferFromString in(s);
    DateTime64 datetime64 {0};

    readDateTime64Text(datetime64, scale, in);
    if (!in.eof())
        throw Exception("String is too long for DateTime64: " + s, ErrorCodes::TOO_LARGE_STRING_SIZE);

    return datetime64.value;
}

Field convertFieldToTypeImpl(const Field & src, const IDataType & type, const IDataType * from_type_hint)
{
    WhichDataType which_type(type);
    WhichDataType which_from_type;
    if (from_type_hint)
    {
        which_from_type = WhichDataType(*from_type_hint);

        // This was added to mitigate converting DateTime64-Field (a typedef to a Decimal64) to DataTypeDate64-compatible type.
        if (from_type_hint && from_type_hint->equals(type))
        {
            return src;
        }
    }

    /// Conversion between Date and DateTime and vice versa.
    if (which_type.isDate() && which_from_type.isDateTime())
    {
        return static_cast<const DataTypeDateTime &>(*from_type_hint).getTimeZone().toDayNum(src.get<UInt64>());
    }
    else if (which_type.isDateTime() && which_from_type.isDate())
    {
        return static_cast<const DataTypeDateTime &>(type).getTimeZone().fromDayNum(DayNum(src.get<UInt64>()));
    }
    else if (type.isValueRepresentedByNumber())
    {
        if (which_type.isUInt8()) return convertNumericType<UInt8>(src, type);
        if (which_type.isUInt16()) return convertNumericType<UInt16>(src, type);
        if (which_type.isUInt32()) return convertNumericType<UInt32>(src, type);
        if (which_type.isUInt64()) return convertNumericType<UInt64>(src, type);
        if (which_type.isInt8()) return convertNumericType<Int8>(src, type);
        if (which_type.isInt16()) return convertNumericType<Int16>(src, type);
        if (which_type.isInt32()) return convertNumericType<Int32>(src, type);
        if (which_type.isInt64()) return convertNumericType<Int64>(src, type);
        if (which_type.isFloat32()) return convertNumericType<Float32>(src, type);
        if (which_type.isFloat64()) return convertNumericType<Float64>(src, type);
        if (auto * ptype = typeid_cast<const DataTypeDecimal<Decimal32> *>(&type)) return convertDecimalType(src, *ptype);
        if (auto * ptype = typeid_cast<const DataTypeDecimal<Decimal64> *>(&type)) return convertDecimalType(src, *ptype);
        if (auto * ptype = typeid_cast<const DataTypeDecimal<Decimal128> *>(&type)) return convertDecimalType(src, *ptype);

        if (!which_type.isDateOrDateTime() && !which_type.isUUID() && !which_type.isEnum())
            throw Exception{"Logical error: unknown numeric type " + type.getName(), ErrorCodes::LOGICAL_ERROR};

        if (which_type.isEnum() && (src.getType() == Field::Types::UInt64 || src.getType() == Field::Types::Int64))
        {
            /// Convert UInt64 or Int64 to Enum's value
            return dynamic_cast<const IDataTypeEnum &>(type).castToValue(src);
        }

        if (which_type.isDateOrDateTime() && !which_type.isDateTime64() && src.getType() == Field::Types::UInt64)
        {
            /// We don't need any conversion UInt64 is under type of Date and DateTime
            return src;
        }
        // TODO (vnemkov): extra cases for DateTime64: converting from integer, converting from Decimal

        if (src.getType() == Field::Types::String)
        {
            if (which_type.isDate())
            {
                /// Convert 'YYYY-MM-DD' Strings to Date
                return stringToDate(src.get<const String &>());
            }
            else if (which_type.isDateTime())
            {
                /// Convert 'YYYY-MM-DD hh:mm:ss' Strings to DateTime
                return stringToDateTime(src.get<const String &>());
            }
            else if (which_type.isDateTime64())
            {
                const auto date_time64 = typeid_cast<const DataTypeDateTime64 *>(&type);
                /// Convert 'YYYY-MM-DD hh:mm:ss.NNNNNNNNN' Strings to DateTime
                return stringToDateTime64(src.get<const String &>(), date_time64->getScale());
            }
            else if (which_type.isUUID())
            {
                return stringToUUID(src.get<const String &>());
            }
            else if (which_type.isEnum())
            {
                /// Convert String to Enum's value
                return dynamic_cast<const IDataTypeEnum &>(type).castToValue(src);
            }
        }
    }
    else if (which_type.isStringOrFixedString())
    {
        if (src.getType() == Field::Types::String)
            return src;
    }
    else if (const DataTypeArray * type_array = typeid_cast<const DataTypeArray *>(&type))
    {
        if (src.getType() == Field::Types::Array)
        {
            const Array & src_arr = src.get<Array>();
            size_t src_arr_size = src_arr.size();

            auto & element_type = *(type_array->getNestedType());
            bool have_unconvertible_element = false;
            Array res(src_arr_size);
            for (size_t i = 0; i < src_arr_size; ++i)
            {
                res[i] = convertFieldToType(src_arr[i], element_type);
                if (res[i].isNull() && !element_type.isNullable())
                {
                    // See the comment for Tuples below.
                    have_unconvertible_element = true;
                }
            }

            return have_unconvertible_element ? Field(Null()) : Field(res);
        }
    }
    else if (const DataTypeTuple * type_tuple = typeid_cast<const DataTypeTuple *>(&type))
    {
        if (src.getType() == Field::Types::Tuple)
        {
            const auto & src_tuple = src.get<Tuple>();
            size_t src_tuple_size = src_tuple.size();
            size_t dst_tuple_size = type_tuple->getElements().size();

            if (dst_tuple_size != src_tuple_size)
                throw Exception("Bad size of tuple in IN or VALUES section. Expected size: "
                    + toString(dst_tuple_size) + ", actual size: " + toString(src_tuple_size), ErrorCodes::TYPE_MISMATCH);

            Tuple res(dst_tuple_size);
            bool have_unconvertible_element = false;
            for (size_t i = 0; i < dst_tuple_size; ++i)
            {
                auto & element_type = *(type_tuple->getElements()[i]);
                res[i] = convertFieldToType(src_tuple[i], element_type);
                if (!res[i].isNull() || element_type.isNullable())
                    continue;

                /*
                 * Either the source element was Null, or the conversion did not
                 * succeed, because the source and the requested types of the
                 * element are compatible, but the value is not convertible
                 * (e.g. trying to convert -1 from Int8 to UInt8). In these
                 * cases, consider the whole tuple also compatible but not
                 * convertible. According to the specification of this function,
                 * we must return Null in this case.
                 *
                 * The following elements might be not even compatible, so it
                 * makes sense to check them to detect user errors. Remember
                 * that there is an unconvertible element, and try to process
                 * the remaining ones. The convertFieldToType for each element
                 * will throw if it detects incompatibility.
                 */
                have_unconvertible_element = true;
            }

            return have_unconvertible_element ? Field(Null()) : Field(res);
        }
    }
    else if (const DataTypeAggregateFunction * agg_func_type = typeid_cast<const DataTypeAggregateFunction *>(&type))
    {
        if (src.getType() != Field::Types::AggregateFunctionState)
            throw Exception(String("Cannot convert ") + src.getTypeName() + " to " + agg_func_type->getName(),
                    ErrorCodes::TYPE_MISMATCH);

        auto & name = src.get<AggregateFunctionStateData>().name;
        if (agg_func_type->getName() != name)
            throw Exception("Cannot convert " + name + " to " + agg_func_type->getName(), ErrorCodes::TYPE_MISMATCH);

        return src;
    }

    if (src.getType() == Field::Types::String)
    {
        const auto col = type.createColumn();
        ReadBufferFromString buffer(src.get<String>());
        type.deserializeAsTextEscaped(*col, buffer, FormatSettings{});

        return (*col)[0];
    }


    // TODO (nemkov): should we attempt to parse value using or `type.deserializeAsTextEscaped()` type.deserializeAsTextEscaped() ?
    throw Exception("Type mismatch in IN or VALUES section. Expected: " + type.getName() + ". Got: "
        + Field::Types::toString(src.getType()), ErrorCodes::TYPE_MISMATCH);
}

}

Field convertFieldToType(const Field & from_value, const IDataType & to_type, const IDataType * from_type_hint)
{
    if (from_value.isNull())
        return from_value;

    if (from_type_hint && from_type_hint->equals(to_type))
        return from_value;

    if (auto * low_cardinality_type = typeid_cast<const DataTypeLowCardinality *>(&to_type))
        return convertFieldToType(from_value, *low_cardinality_type->getDictionaryType(), from_type_hint);
    else if (auto * nullable_type = typeid_cast<const DataTypeNullable *>(&to_type))
    {
        const IDataType & nested_type = *nullable_type->getNestedType();
        if (from_type_hint && from_type_hint->equals(nested_type))
            return from_value;
        return convertFieldToTypeImpl(from_value, nested_type, from_type_hint);
    }
    else
        return convertFieldToTypeImpl(from_value, to_type, from_type_hint);
}


}