8.1.1 Processing Warnings — MySQL Connectors 1.0

8.1.1 Предупреждения при обработке

Аналогично выполнению отдельных операторов, подтверждение или откат транзакции также может вызывать предупреждения. Для обработки этих предупреждений необходимо проверить объект результата ответа Session.commit(); или Session.rollback();.

Это показано в следующем примере. Пример предполагает, что схема теста существует, а коллекция my_collection не существует.

Код MySQL Shell на JavaScript

var mysqlx = require('mysqlx');

// Connect to server
var mySession = mysqlx.getSession( {
        host: 'localhost', port: 33060,
        user: 'user', password: 'password' } );

// Get the Schema test
var myDb = mySession.getSchema('test');

// Create a new collection
var myColl = myDb.createCollection('my_collection');

// Start a transaction
mySession.startTransaction();
try
{
    myColl.add({'name': 'Rohit', 'age': 18, 'height': 1.76}).execute();
    myColl.add({'name': 'Misaki', 'age': 24, 'height': 1.65}).execute();
    myColl.add({'name': 'Leon', 'age': 39, 'height': 1.9}).execute();

    // Commit the transaction if everything went well
    var reply = mySession.commit();

    // handle warnings
    if (reply.warningCount){
      var warnings = reply.getWarnings();
      for (index in warnings){
        var warning = warnings[index];
        print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n');
      }
    }

    print ('Data inserted successfully.');
}
catch(err)
{
    // Rollback the transaction in case of an error
    reply = mySession.rollback();

    // handle warnings
    if (reply.warningCount){
      var warnings = reply.getWarnings();
      for (index in warnings){
        var warning = warnings[index];
        print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n');
      }
    }

    // Printing the error message
    print ('Data could not be inserted: ' + err.message);
}

Код MySQL Shell на Python

from mysqlsh import mysqlx

# Connect to server
mySession = mysqlx.get_session( {
        'host': 'localhost', 'port': 33060,
        'user': 'user', 'password': 'password' } )

# Get the Schema test
myDb = mySession.get_schema('test')

# Create a new collection
myColl = myDb.create_collection('my_collection')

# Start a transaction
mySession.start_transaction()
try:
    myColl.add({'name': 'Rohit', 'age': 18, 'height': 1.76}).execute()
    myColl.add({'name': 'Misaki', 'age': 24, 'height': 1.65}).execute()
    myColl.add({'name': 'Leon', 'age': 39, 'height': 1.9}).execute()

    # Commit the transaction if everything went well
    reply = mySession.commit()

    # handle warnings
    if reply.warning_count:
      for warning in result.get_warnings():
        print('Type [%s] (Code %s): %s\n' % (warning.level, warning.code, warning.message))

    print('Data inserted successfully.')
except Exception as err:
    # Rollback the transaction in case of an error
    reply = mySession.rollback()

    # handle warnings
    if reply.warning_count:
      for warning in result.get_warnings():
        print('Type [%s] (Code %s): %s\n' % (warning.level, warning.code, warning.message))

    # Printing the error message
    print('Data could not be inserted: %s' % str(err))

Код C#

// Connect to server
var session = MySQLX.GetSession("server=localhost;port=33060;user=user;password=password;");

// Get the Schema test
var db = session.GetSchema("test");

// Create a new collection
var myColl = db.CreateCollection("my_collection");

// Start a transaction
session.StartTransaction();
int warningCount = 0;
try
{
	var result = myColl.Add(new { name = "Rohit", age = 18, height = 1.76}).Execute();
	warningCount += result.Warnings.Count;
	result = myColl.Add(new { name = "Misaki", age = 24, height = 1.65}).Execute();
	warningCount += result.Warnings.Count;
	result = myColl.Add(new { name = "Leon", age = 39, height = 1.9}).Execute();
	warningCount += result.Warnings.Count;

	// Commit the transaction if everything went well
	session.Commit();
	if(warningCount > 0)
	{
	  // handle warnings
	}

	Console.WriteLine("Data inserted successfully.");
}
catch (Exception err)
{
	// Rollback the transaction in case of an error
	session.Rollback();
	if(warningCount > 0)
	{
	  // handle warnings
	}

	// Printing the error message
	Console.WriteLine("Data could not be inserted: " + err.Message);
}

Код Python

import mysqlx

# Connect to server
my_session = mysqlx.get_session({
    'host': 'localhost', 'port': 33060,
    'user': 'user', 'password': 'password'
})

# Get the Schema test
my_schema = my_session.get_schema('test')

# Create a new collection
my_coll = my_schema.create_collection('my_collection')

# Start a transaction
my_session.start_transaction()
try:
    my_coll.add({'name': 'Rohit', 'age': 18, 'height': 1.76}).execute()
    my_coll.add({'name': 'Misaki', 'age': 24, 'height': 1.65}).execute()
    my_coll.add({'name': 'Leon', 'age': 39, 'height': 1.9}).execute()

    # Commit the transaction if everything went well
    result = my_session.commit()

    # handle warnings
    if result.get_warnings_count() > 0:
        for warning in result.get_warnings():
            print('Type [{0}] (Code {1}): {2}'.format(warning['level'], warning['code'], warning['msg']))

    print('Data inserted successfully.')
except Exception as err:
    # Rollback the transaction in case of an error
    result = my_session.rollback()

    # handle warnings
    if result.get_warnings_count() > 0:
        for warning in result.get_warnings():
            print('Type [{0}] (Code {1}): {2}'.format(warning['level'], warning['code'], warning['msg']))

    # Printing the error message
    print('Data could not be inserted: {0}'.format(err))

Код Java

// c.f. "standard transaction handling"

Код C++

/*
  Connector/C++ does not yet provide access to transaction warnings
  -- Session methods commit() and rollback() do not return a result object.
*/

По умолчанию все предупреждения отправляются от сервера клиенту. Если известно, что операция генерирует много предупреждений, и они не нужны приложению, то отправку предупреждений можно подавить. Это помогает сохранить пропускную способность. session.setFetchWarnings() управляет тем, игнорируются ли предупреждения на сервере или отправляются клиенту. session.getFetchWarnings() используется для получения текущих настроек.

Код MySQL Shell на JavaScript

var mysqlx = require('mysqlx');

function process_warnings(result){
  if (result.getWarningCount()){
    var warnings = result.getWarnings();
    for (index in warnings){
      var warning = warnings[index];
      print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n');
    }
  }
  else{
    print ("No warnings were returned.\n");
  }
}

// Connect to server
var mySession = mysqlx.getSession( {
  host: 'localhost', port: 33060,
  user: 'user', password: 'password' } );

// Disables warning generation
mySession.setFetchWarnings(false);
var result = mySession.sql('drop schema if exists unexisting').execute();
process_warnings(result);

// Enables warning generation
mySession.setFetchWarnings(true);
var result = mySession.sql('drop schema if exists unexisting').execute();
process_warnings(result);

Код MySQL Shell на Python

from mysqlsh import mysqlx

def process_warnings(result):
  if result.get_warnings_count():
    for warning in result.get_warnings():
      print('Type [%s] (Code %s): %s\n' % (warning.level, warning.code, warning.message))
  else:
    print("No warnings were returned.\n")


# Connect to server
mySession = mysqlx.get_session( {
  'host': 'localhost', 'port': 33060,
  'user': 'user', 'password': 'password' } );

# Disables warning generation
mySession.set_fetch_warnings(False)
result = mySession.sql('drop schema if exists unexisting').execute()
process_warnings(result)

# Enables warning generation
mySession.set_fetch_warnings(True)
result = mySession.sql('drop schema if exists unexisting').execute()
process_warnings(result)

Код Java

// Connect to server
Session mySession = new SessionFactory().getSession("mysqlx://localhost:33060/test?user=user&password=password");

Schema db = mySession.getSchema("test");

// Create a new collection
Collection myColl = db.createCollection("my_collection");

// Start a transaction
mySession.startTransaction();
try {
    Result res = myColl.add("{\"name\":\"Rohit\", \"age\":18}", "{\"name\":\"Misaki\", \"age\":24}", "{\"name\":\"Leon\", \"age\":39}").execute();

    System.out.println(res.getWarningsCount());

    Iterator<Warning> warnings = res.getWarnings();
    while (warnings.hasNext()) {
        Warning warn = warnings.next();
        System.out.println(warn.getCode() + ", " + warn.getLevel() + ", " + warn.getMessage());
    }

    mySession.commit();
    System.out.println("Data inserted successfully.");
} catch (Exception err) {
    // Rollback the transaction in case of an error
    mySession.rollback();

    // Printing the error message
    System.out.println("Data could not be inserted: " + err.getMessage());
}