Function tryConvertToMapKeyField

src/DataTypes/MapHelpers.cpp:143–155

}

Field tryConvertToMapKeyField(const DataTypePtr & key_type, const String & key_name)
{
    try
    {
        return convertToMapKeyField(key_type, key_name);
    }
    catch (...)
    {
        /// return Null field if failed to convert key_name to field, this could be happend if key_name is 
        /// got by getColumnName from a converted key field. See getMapKeyField() in QueryNormalizer.cpp
        return Null();
    }
}

Field convertToMapKeyField(const DataTypePtr & key_type, const String & key_name)
{