java.lang.Object
- io.debezium.jdbc.JdbcValueConverters
- - io.debezium.connector.mysql.MySqlValueConverters

All Implemented Interfaces:

ValueConverterProvider
```
@Immutable
public class MySqlValueConverters
extends JdbcValueConverters
```
MySQL-specific customization of the conversions from JDBC values obtained from the MySQL binlog client library.
This class always uses UTC for the default time zone when converting values without timezone information to values that require timezones. This is because MySQL TIMESTAMP values are always stored in UTC (unlike DATETIME values) and are replicated in this form. Meanwhile, the MySQL Binlog Client library will deserialize these as Timestamp values that have no timezone and, therefore, are presumed to be in UTC. When the column is properly marked with a Types.TIMESTAMP_WITH_TIMEZONE type, the converters will need to convert that Timestamp value into an OffsetDateTime using the default time zone, which always is UTC.

Author:

Randall Hauch

See Also:

AbstractRowsEventDataDeserializer

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static interface MySqlValueConverters.ParsingErrorHandler
- Nested classes/interfaces inherited from class io.debezium.jdbc.JdbcValueConverters
  JdbcValueConverters.BigIntUnsignedMode, JdbcValueConverters.DecimalMode

Field Summary

Fields
Modifier and Type	Field	Description
`private static Pattern`	`DATE_FIELD_PATTERN`	Used to parse values of DATE columns.
`private static org.slf4j.Logger`	`LOGGER`
`private MySqlValueConverters.ParsingErrorHandler`	`parsingErrorHandler`
`private static Pattern`	`TIME_FIELD_PATTERN`	Used to parse values of TIME columns.
`private static Pattern`	`TIMESTAMP_FIELD_PATTERN`	Used to parse values of TIMESTAMP columns.

Fields inherited from class io.debezium.jdbc.JdbcValueConverters
adaptiveTimeMicrosecondsPrecisionMode, adaptiveTimePrecisionMode, bigIntUnsignedMode, binaryMode, decimalMode, logger

Constructor Summary

Constructors
Constructor	Description
`MySqlValueConverters(JdbcValueConverters.DecimalMode decimalMode, TemporalPrecisionMode temporalPrecisionMode, JdbcValueConverters.BigIntUnsignedMode bigIntUnsignedMode, CommonConnectorConfig.BinaryHandlingMode binaryMode)`	Create a new instance that always uses UTC for the default time zone when_needed converting values without timezone information to values that require timezones.
`MySqlValueConverters(JdbcValueConverters.DecimalMode decimalMode, TemporalPrecisionMode temporalPrecisionMode, JdbcValueConverters.BigIntUnsignedMode bigIntUnsignedMode, CommonConnectorConfig.BinaryHandlingMode binaryMode, TemporalAdjuster adjuster, MySqlValueConverters.ParsingErrorHandler parsingErrorHandler)`	Create a new instance that always uses UTC for the default time zone when converting values without timezone information to values that require timezones.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static Temporal`	`adjustTemporal(Temporal temporal)`	A utility method that adjusts ambiguous 2-digit year values of DATETIME, DATE, and TIMESTAMP types using these MySQL-specific rules: Year values in the range 00-69 are converted to 2000-2069. Year values in the range 70-99 are converted to 1970-1999.
`protected ByteOrder`	`byteOrderOfBitType()`
`protected Charset`	`charsetFor(Column column)`	Return the `Charset` instance with the MySQL-specific character set name used by the given column.
`static boolean`	`containsZeroValuesInDatePart(String timestampString, Column column, Table table)`
`protected Object`	`convertDurationToMicroseconds(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Converts a value object for an expected type of `Duration` to `Long` values that represents the time in microseconds.
`protected Object`	`convertEnumToString(List<String> options, Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Converts a value object for a MySQL `ENUM`, which is represented in the binlog events as an integer value containing the index of the enum option.
`ValueConverter`	`converter(Column column, org.apache.kafka.connect.data.Field fieldDefn)`
`protected Object`	`convertGeometry(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a GEOMETRY `byte[]` value to a Geometry value used in a `SourceRecord`.
`protected Object`	`convertJson(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the `String` `byte[]` value to a string value used in a `SourceRecord`.
`protected Object`	`convertPoint(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a POINT `byte[]` value to a Point value used in a `SourceRecord`.
`protected Object`	`convertSetToString(List<String> options, Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Converts a value object for a MySQL `SET`, which is represented in the binlog events contain a long number in which every bit corresponds to a different option.
`protected String`	`convertSetValue(Column column, long indexes, List<String> options)`
`protected Object`	`convertString(Column column, org.apache.kafka.connect.data.Field fieldDefn, Charset columnCharset, Object data)`	Convert the `String` or `byte[]` value to a string value used in a `SourceRecord`.
`protected Object`	`convertTimestampToLocalDateTime(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`
`protected Object`	`convertUnsignedBigint(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a Unsigned BIGINT value to the correct Unsigned INT representation.
`protected Object`	`convertUnsignedInt(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a Unsigned INT value to the correct Unsigned INT representation.
`protected Object`	`convertUnsignedMediumint(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a Unsigned MEDIUMINT value to the correct Unsigned SMALLINT representation.
`protected Object`	`convertUnsignedSmallint(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a Unsigned SMALLINT value to the correct Unsigned SMALLINT representation.
`protected Object`	`convertUnsignedTinyint(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Convert the a value representing a Unsigned TINYINT value to the correct Unsigned TINYINT representation.
`protected Object`	`convertYearToInt(Column column, org.apache.kafka.connect.data.Field fieldDefn, Object data)`	Converts a value object for a MySQL `YEAR`, which appear in the binlog as an integer though returns from the MySQL JDBC driver as either a short or a `Date`.
`static void`	`defaultParsingErrorHandler(String message, Exception exception)`
`protected List<String>`	`extractEnumAndSetOptions(Column column)`
`protected String`	`extractEnumAndSetOptionsAsString(Column column)`
`protected boolean`	`isGeometryCollection(String upperCaseTypeName)`	Determine if the uppercase form of a column's type is geometry collection independent of JDBC driver or server version.
`protected boolean`	`matches(String upperCaseTypeName, String upperCaseMatch)`	Determine if the uppercase form of a column's type exactly matches or begins with the specified prefix.
`org.apache.kafka.connect.data.SchemaBuilder`	`schemaBuilder(Column column)`
`static Duration`	`stringToDuration(String timeString)`
`static LocalDate`	`stringToLocalDate(String dateString, Column column, Table table)`
`protected ByteBuffer`	`toByteBuffer(Column column, byte[] data)`

Methods inherited from class io.debezium.jdbc.JdbcValueConverters
convertBigInt, convertBinary, convertBinaryToBase64, convertBinaryToBytes, convertBinaryToHex, convertBit, convertBits, convertBits, convertBoolean, convertDateToEpochDays, convertDateToEpochDaysAsDate, convertDecimal, convertDouble, convertFloat, convertInteger, convertNumeric, convertReal, convertRowId, convertSmallInt, convertString, convertTime, convertTimestampToEpochMicros, convertTimestampToEpochMillis, convertTimestampToEpochMillisAsDate, convertTimestampToEpochNanos, convertTimestampWithZone, convertTimeToMicrosPastMidnight, convertTimeToMillisPastMidnight, convertTimeToMillisPastMidnightAsDate, convertTimeToNanosPastMidnight, convertTimeWithZone, convertTinyInt, convertValue, getTimePrecision, handleUnknownData, padLittleEndian, toBigDecimal, unexpectedBinary, withScaleAdjustedIfNeeded

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - LOGGER
```
private static final org.slf4j.Logger LOGGER
```
  - TIME_FIELD_PATTERN
```
private static final Pattern TIME_FIELD_PATTERN
```
    Used to parse values of TIME columns. Format: 000:00:00.000000.
  - DATE_FIELD_PATTERN
```
private static final Pattern DATE_FIELD_PATTERN
```
    Used to parse values of DATE columns. Format: 000-00-00.
  - TIMESTAMP_FIELD_PATTERN
```
private static final Pattern TIMESTAMP_FIELD_PATTERN
```
    Used to parse values of TIMESTAMP columns. Format: 000-00-00 00:00:00.000.
  - parsingErrorHandler
```
private final MySqlValueConverters.ParsingErrorHandler parsingErrorHandler
```
- Constructor Detail
  - MySqlValueConverters
```
public MySqlValueConverters(JdbcValueConverters.DecimalMode decimalMode,
                            TemporalPrecisionMode temporalPrecisionMode,
                            JdbcValueConverters.BigIntUnsignedMode bigIntUnsignedMode,
                            CommonConnectorConfig.BinaryHandlingMode binaryMode)
```
    Create a new instance that always uses UTC for the default time zone when_needed converting values without timezone information to values that require timezones.
    
    Parameters:
    
    decimalMode - how DECIMAL and NUMERIC values should be treated; may be null if JdbcValueConverters.DecimalMode.PRECISE is to be used
    
    temporalPrecisionMode - temporal precision mode based on TemporalPrecisionMode
    
    bigIntUnsignedMode - how BIGINT UNSIGNED values should be treated; may be null if JdbcValueConverters.BigIntUnsignedMode.PRECISE is to be used
    
    binaryMode - how binary columns should be represented
  - MySqlValueConverters
```
public MySqlValueConverters(JdbcValueConverters.DecimalMode decimalMode,
                            TemporalPrecisionMode temporalPrecisionMode,
                            JdbcValueConverters.BigIntUnsignedMode bigIntUnsignedMode,
                            CommonConnectorConfig.BinaryHandlingMode binaryMode,
                            TemporalAdjuster adjuster,
                            MySqlValueConverters.ParsingErrorHandler parsingErrorHandler)
```
    Create a new instance that always uses UTC for the default time zone when converting values without timezone information to values that require timezones.
    
    Parameters:
    
    decimalMode - how DECIMAL and NUMERIC values should be treated; may be null if JdbcValueConverters.DecimalMode.PRECISE is to be used
    
    temporalPrecisionMode - temporal precision mode based on TemporalPrecisionMode
    
    bigIntUnsignedMode - how BIGINT UNSIGNED values should be treated; may be null if JdbcValueConverters.BigIntUnsignedMode.PRECISE is to be used
    
    binaryMode - how binary columns should be represented
    
    adjuster - a temporal adjuster to make a database specific time modification before conversion
    
    handler - for errors during postponed binlog parsing
- Method Detail
  - adjustTemporal
```
public static Temporal adjustTemporal(Temporal temporal)
```
    A utility method that adjusts ambiguous 2-digit year values of DATETIME, DATE, and TIMESTAMP types using these MySQL-specific rules:
    
    Year values in the range 00-69 are converted to 2000-2069.
    
    Year values in the range 70-99 are converted to 1970-1999.
    Parameters:
    
    temporal - the temporal instance to adjust; may not be null
    
    Returns:
    
    the possibly adjusted temporal instance; never null
  - byteOrderOfBitType
```
protected ByteOrder byteOrderOfBitType()
```
    Overrides:
    
    byteOrderOfBitType in class JdbcValueConverters
  - schemaBuilder
```
public org.apache.kafka.connect.data.SchemaBuilder schemaBuilder(Column column)
```
    Specified by:
    
    schemaBuilder in interface ValueConverterProvider
    
    Overrides:
    
    schemaBuilder in class JdbcValueConverters
  - converter
```
public ValueConverter converter(Column column,
                                org.apache.kafka.connect.data.Field fieldDefn)
```
    Specified by:
    
    converter in interface ValueConverterProvider
    
    Overrides:
    
    converter in class JdbcValueConverters
  - charsetFor
```
protected Charset charsetFor(Column column)
```
    Return the Charset instance with the MySQL-specific character set name used by the given column.
    
    Parameters:
    
    column - the column in which the character set is used; never null
    
    Returns:
    
    the Java Charset, or null if there is no mapping
  - convertJson
```
protected Object convertJson(Column column,
                             org.apache.kafka.connect.data.Field fieldDefn,
                             Object data)
```
    Convert the String byte[] value to a string value used in a SourceRecord.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertString
```
protected Object convertString(Column column,
                               org.apache.kafka.connect.data.Field fieldDefn,
                               Charset columnCharset,
                               Object data)
```
    Convert the String or byte[] value to a string value used in a SourceRecord.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    columnCharset - the Java character set in which column byte[] values are encoded; may not be null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertYearToInt
```
protected Object convertYearToInt(Column column,
                                  org.apache.kafka.connect.data.Field fieldDefn,
                                  Object data)
```
    Converts a value object for a MySQL YEAR, which appear in the binlog as an integer though returns from the MySQL JDBC driver as either a short or a Date.
    
    Parameters:
    
    column - the column definition describing the data value; never null
    
    fieldDefn - the field definition; never null
    
    data - the data object to be converted into a year literal integer value; never null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertEnumToString
```
protected Object convertEnumToString(List<String> options,
                                     Column column,
                                     org.apache.kafka.connect.data.Field fieldDefn,
                                     Object data)
```
    Converts a value object for a MySQL ENUM, which is represented in the binlog events as an integer value containing the index of the enum option. The MySQL JDBC driver returns a string containing the option, so this method calculates the same.
    
    Parameters:
    
    options - the characters that appear in the same order as defined in the column; may not be null
    
    column - the column definition describing the data value; never null
    
    fieldDefn - the field definition; never null
    
    data - the data object to be converted into an ENUM literal String value
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertSetToString
```
protected Object convertSetToString(List<String> options,
                                    Column column,
                                    org.apache.kafka.connect.data.Field fieldDefn,
                                    Object data)
```
    Converts a value object for a MySQL SET, which is represented in the binlog events contain a long number in which every bit corresponds to a different option. The MySQL JDBC driver returns a string containing the comma-separated options, so this method calculates the same.
    
    Parameters:
    
    options - the characters that appear in the same order as defined in the column; may not be null
    
    column - the column definition describing the data value; never null
    
    fieldDefn - the field definition; never null
    
    data - the data object to be converted into an SET literal String value; never null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - matches
```
protected boolean matches(String upperCaseTypeName,
                          String upperCaseMatch)
```
    Determine if the uppercase form of a column's type exactly matches or begins with the specified prefix. Note that this logic works when the column's type contains the type name followed by parentheses.
    
    Parameters:
    
    upperCaseTypeName - the upper case form of the column's type name
    
    upperCaseMatch - the upper case form of the expected type or prefix of the type; may not be null
    
    Returns:
    
    true if the type matches the specified type, or false otherwise
  - isGeometryCollection
```
protected boolean isGeometryCollection(String upperCaseTypeName)
```
    Determine if the uppercase form of a column's type is geometry collection independent of JDBC driver or server version.
    
    Parameters:
    
    upperCaseTypeName - the upper case form of the column's type name
    
    Returns:
    
    true if the type is geometry collection
  - extractEnumAndSetOptions
```
protected List<String> extractEnumAndSetOptions(Column column)
```
  - extractEnumAndSetOptionsAsString
```
protected String extractEnumAndSetOptionsAsString(Column column)
```
  - convertSetValue
```
protected String convertSetValue(Column column,
                                 long indexes,
                                 List<String> options)
```
  - convertPoint
```
protected Object convertPoint(Column column,
                              org.apache.kafka.connect.data.Field fieldDefn,
                              Object data)
```
    Convert the a value representing a POINT byte[] value to a Point value used in a SourceRecord.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertGeometry
```
protected Object convertGeometry(Column column,
                                 org.apache.kafka.connect.data.Field fieldDefn,
                                 Object data)
```
    Convert the a value representing a GEOMETRY byte[] value to a Geometry value used in a SourceRecord.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - toByteBuffer
```
protected ByteBuffer toByteBuffer(Column column,
                                  byte[] data)
```
    Overrides:
    
    toByteBuffer in class JdbcValueConverters
  - convertUnsignedTinyint
```
protected Object convertUnsignedTinyint(Column column,
                                        org.apache.kafka.connect.data.Field fieldDefn,
                                        Object data)
```
    Convert the a value representing a Unsigned TINYINT value to the correct Unsigned TINYINT representation.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertUnsignedSmallint
```
protected Object convertUnsignedSmallint(Column column,
                                         org.apache.kafka.connect.data.Field fieldDefn,
                                         Object data)
```
    Convert the a value representing a Unsigned SMALLINT value to the correct Unsigned SMALLINT representation.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertUnsignedMediumint
```
protected Object convertUnsignedMediumint(Column column,
                                          org.apache.kafka.connect.data.Field fieldDefn,
                                          Object data)
```
    Convert the a value representing a Unsigned MEDIUMINT value to the correct Unsigned SMALLINT representation.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertUnsignedInt
```
protected Object convertUnsignedInt(Column column,
                                    org.apache.kafka.connect.data.Field fieldDefn,
                                    Object data)
```
    Convert the a value representing a Unsigned INT value to the correct Unsigned INT representation.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertUnsignedBigint
```
protected Object convertUnsignedBigint(Column column,
                                       org.apache.kafka.connect.data.Field fieldDefn,
                                       Object data)
```
    Convert the a value representing a Unsigned BIGINT value to the correct Unsigned INT representation.
    
    Parameters:
    
    column - the column in which the value appears
    
    fieldDefn - the field definition for the SourceRecord's Schema; never null
    
    data - the data; may be null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertDurationToMicroseconds
```
protected Object convertDurationToMicroseconds(Column column,
                                               org.apache.kafka.connect.data.Field fieldDefn,
                                               Object data)
```
    Converts a value object for an expected type of Duration to Long values that represents the time in microseconds.
    Per the JDBC specification, databases should return Time instances, but that's not working because it can only handle Daytime 00:00:00-23:59:59. We use Duration instead that can handle the range of -838:59:59.000000 to 838:59:59.000000 of a MySQL TIME type and transfer data as signed INT64 which reflects the DB value converted to microseconds.
    
    Parameters:
    
    column - the column definition describing the data value; never null
    
    fieldDefn - the field definition; never null
    
    data - the data object to be converted into a Duration type; never null
    
    Returns:
    
    the converted value, or null if the conversion could not be made and the column allows nulls
    
    Throws:
    
    IllegalArgumentException - if the value could not be converted but the column does not allow nulls
  - convertTimestampToLocalDateTime
```
protected Object convertTimestampToLocalDateTime(Column column,
                                                 org.apache.kafka.connect.data.Field fieldDefn,
                                                 Object data)
```
  - stringToDuration
```
public static Duration stringToDuration(String timeString)
```
  - stringToLocalDate
```
public static LocalDate stringToLocalDate(String dateString,
                                          Column column,
                                          Table table)
```
  - containsZeroValuesInDatePart
```
public static boolean containsZeroValuesInDatePart(String timestampString,
                                                   Column column,
                                                   Table table)
```
  - defaultParsingErrorHandler
```
public static void defaultParsingErrorHandler(String message,
                                              Exception exception)
```

Class MySqlValueConverters

Nested Class Summary

Nested classes/interfaces inherited from class io.debezium.jdbc.JdbcValueConverters

Field Summary

Fields inherited from class io.debezium.jdbc.JdbcValueConverters

Constructor Summary

Method Summary

Methods inherited from class io.debezium.jdbc.JdbcValueConverters

Methods inherited from class java.lang.Object

Field Detail

LOGGER

TIME_FIELD_PATTERN

DATE_FIELD_PATTERN

TIMESTAMP_FIELD_PATTERN

parsingErrorHandler

Constructor Detail

MySqlValueConverters

MySqlValueConverters

Method Detail

adjustTemporal

byteOrderOfBitType

schemaBuilder

converter

charsetFor

convertJson

convertString

convertYearToInt

convertEnumToString

convertSetToString

matches

isGeometryCollection

extractEnumAndSetOptions

extractEnumAndSetOptionsAsString

convertSetValue

convertPoint

convertGeometry

toByteBuffer

convertUnsignedTinyint

convertUnsignedSmallint

convertUnsignedMediumint

convertUnsignedInt

convertUnsignedBigint

convertDurationToMicroseconds

convertTimestampToLocalDateTime

stringToDuration

stringToLocalDate

containsZeroValuesInDatePart

defaultParsingErrorHandler