ReadPreference

java.lang.Object
- com.mongodb.ReadPreference

Direct Known Subclasses:

ReadPreference.PrimaryReadPreference, ReadPreference.TaggedReadPreference, TaggableReadPreference
```
public abstract class ReadPreference
extends java.lang.Object
```
An abstract class that represents preferred replica set members to which a query or command can be sent.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`private static class`	`ReadPreference.PrimaryReadPreference` Preference to read from primary only.
`static class`	`ReadPreference.TaggedReadPreference` Deprecated. As of release 2.9, replaced by `secondaryPreferred(DBObject, DBObject...)`

Field Summary

Fields
Modifier and Type	Field and Description
`private static ReadPreference`	`_NEAREST`
`private static ReadPreference`	`_PRIMARY`
`private static ReadPreference`	`_PRIMARY_PREFERRED`
`private static ReadPreference`	`_SECONDARY`
`private static ReadPreference`	`_SECONDARY_PREFERRED`
`static ReadPreference`	`PRIMARY` Deprecated. As of release 2.9.0, replaced by `ReadPreference.primary()`
`static ReadPreference`	`SECONDARY` Deprecated. As of release 2.9.0, replaced by `ReadPreference.secondaryPreferred()`

Constructor Summary

Constructors
Constructor and Description

ReadPreference()

Constructors
Constructor and Description
`ReadPreference()`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`(package private) abstract java.util.List<ServerDescription>`	`choose(ClusterDescription clusterDescription)`
`abstract java.lang.String`	`getName()` The name of this read preference.
`abstract boolean`	`isSlaveOk()` True if this read preference allows reading from a secondary member of a replica set.
`static ReadPreference`	`nearest()` Gets a read preference that forces reads to a primary or a secondary.
`static TaggableReadPreference`	`nearest(DBObject firstTagSet, DBObject... remainingTagSets)` Deprecated. use factory methods that take `TagSet` instead
`static TaggableReadPreference`	`nearest(java.util.List<TagSet> tagSetList)` Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`nearest(TagSet tagSet)` Gets a read preference that forces reads to the primary or a secondary with the given set of tags.
`static ReadPreference`	`primary()` Gets a read preference that forces read to the primary.
`static ReadPreference`	`primaryPreferred()` Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
`static TaggableReadPreference`	`primaryPreferred(DBObject firstTagSet, DBObject... remainingTagSets)` Deprecated. use factory methods that take `TagSet` instead
`static TaggableReadPreference`	`primaryPreferred(java.util.List<TagSet> tagSetList)` Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`primaryPreferred(TagSet tagSet)` Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags.
`static ReadPreference`	`secondary()` Gets a read preference that forces reads to a secondary.
`static TaggableReadPreference`	`secondary(DBObject firstTagSet, DBObject... remainingTagSets)` Deprecated. use factory methods that take `TagSet` instead
`static TaggableReadPreference`	`secondary(java.util.List<TagSet> tagSetList)` Gets a read preference that forces reads to a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`secondary(TagSet tagSet)` Gets a read preference that forces reads to a secondary with the given set of tags.
`static ReadPreference`	`secondaryPreferred()` Gets a read preference that forces reads to a secondary if one is available, otherwise to the primary.
`static TaggableReadPreference`	`secondaryPreferred(DBObject firstTagSet, DBObject... remainingTagSets)` Deprecated. use factory methods that take `TagSet` instead
`static TaggableReadPreference`	`secondaryPreferred(java.util.List<TagSet> tagSetList)` Gets a read preference that forces reads to a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`secondaryPreferred(TagSet tagSet)` Gets a read preference that forces reads to a secondary with the given set of tags, or the primary is none are available.
`abstract DBObject`	`toDBObject()` Deprecated. for internal use only
`private static TagSet`	`toTags(DBObject tagsDocument)`
`private static java.util.List<TagSet>`	`toTagsList(DBObject firstTagSet, DBObject... remainingTagSets)`
`static ReadPreference`	`valueOf(java.lang.String name)` Creates a read preference from the given read preference name.
`static TaggableReadPreference`	`valueOf(java.lang.String name, DBObject firstTagSet, DBObject... remainingTagSets)` Deprecated. use method that takes a `List<TagSet>`
`static TaggableReadPreference`	`valueOf(java.lang.String name, java.util.List<TagSet> tagSetList)` Creates a taggable read preference from the given read preference name and list of tag sets.
`static ReadPreference`	`withTags(DBObject tags)` Deprecated. As of release 2.9.0, replaced by `ReadPreference.secondaryPreferred(DBObject firstTagSet, DBObject... remainingTagSets)`
`static ReadPreference`	`withTags(java.util.Map<java.lang.String,java.lang.String> tags)` Deprecated. As of release 2.9.0, replaced by `ReadPreference.secondaryPreferred(DBObject firstTagSet, DBObject... remainingTagSets)`

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

- Field Detail
  - PRIMARY
```
@Deprecated
public static final ReadPreference PRIMARY
```
    Deprecated. As of release 2.9.0, replaced by ReadPreference.primary()
    
    A primary read preference. Equivalent to calling ReadPreference.primary().
    
    See Also:
    
    primary()
  - SECONDARY
```
@Deprecated
public static final ReadPreference SECONDARY
```
    Deprecated. As of release 2.9.0, replaced by ReadPreference.secondaryPreferred()
    
    A secondary-preferred read preference. Equivalent to calling ReadPreference.secondaryPreferred. This reference should really have been called ReadPreference.SECONDARY_PREFERRED, but the naming of it preceded the idea of distinguishing between secondary and secondary-preferred, so for backwards compatibility, leaving the name as is with the behavior as it was when it was created.
    
    See Also:
    
    secondary(), secondaryPreferred()
  - _PRIMARY
```
private static final ReadPreference _PRIMARY
```
  - _SECONDARY
```
private static final ReadPreference _SECONDARY
```
  - _SECONDARY_PREFERRED
```
private static final ReadPreference _SECONDARY_PREFERRED
```
  - _PRIMARY_PREFERRED
```
private static final ReadPreference _PRIMARY_PREFERRED
```
  - _NEAREST
```
private static final ReadPreference _NEAREST
```
- Constructor Detail
  - ReadPreference
```
ReadPreference()
```
- Method Detail
  - isSlaveOk
```
public abstract boolean isSlaveOk()
```
    True if this read preference allows reading from a secondary member of a replica set.
    
    Returns:
    
    if reading from a secondary is ok
  - toDBObject
```
@Deprecated
public abstract DBObject toDBObject()
```
    Deprecated. for internal use only
    
    Converts this read preference into a DBObject.
    
    Returns:
    
    a DBObject representation of this preference
  - getName
```
public abstract java.lang.String getName()
```
    The name of this read preference.
    
    Returns:
    
    the name
  - choose
```
abstract java.util.List<ServerDescription> choose(ClusterDescription clusterDescription)
```
  - primary
```
public static ReadPreference primary()
```
    Gets a read preference that forces read to the primary.
    
    Returns:
    
    ReadPreference which reads from primary only
  - primaryPreferred
```
public static ReadPreference primaryPreferred()
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
    
    Returns:
    
    ReadPreference which reads primary if available.
  - secondary
```
public static ReadPreference secondary()
```
    Gets a read preference that forces reads to a secondary.
    
    Returns:
    
    ReadPreference which reads secondary.
  - secondaryPreferred
```
public static ReadPreference secondaryPreferred()
```
    Gets a read preference that forces reads to a secondary if one is available, otherwise to the primary.
    
    Returns:
    
    ReadPreference which reads secondary if available, otherwise from primary.
  - nearest
```
public static ReadPreference nearest()
```
    Gets a read preference that forces reads to a primary or a secondary.
    
    Returns:
    
    ReadPreference which reads nearest
  - primaryPreferred
```
public static TaggableReadPreference primaryPreferred(TagSet tagSet)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to.
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.\
    
    Since:
    
    2.13
  - secondary
```
public static TaggableReadPreference secondary(TagSet tagSet)
```
    Gets a read preference that forces reads to a secondary with the given set of tags.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    Since:
    
    2.13
  - secondaryPreferred
```
public static TaggableReadPreference secondaryPreferred(TagSet tagSet)
```
    Gets a read preference that forces reads to a secondary with the given set of tags, or the primary is none are available.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    Since:
    
    2.13
  - nearest
```
public static TaggableReadPreference nearest(TagSet tagSet)
```
    Gets a read preference that forces reads to the primary or a secondary with the given set of tags.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    Since:
    
    2.13
  - primaryPreferred
```
public static TaggableReadPreference primaryPreferred(java.util.List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or failing if no secondary can be found that matches any of the tag sets in the list.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.
    
    Since:
    
    2.13
  - secondary
```
public static TaggableReadPreference secondary(java.util.List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or failing if no secondary can be found that matches any of the tag sets in the list.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    Since:
    
    2.13
  - secondaryPreferred
```
public static TaggableReadPreference secondaryPreferred(java.util.List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or the primary if none are available.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    Since:
    
    2.13
  - nearest
```
public static TaggableReadPreference nearest(java.util.List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or the primary if none are available.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    Since:
    
    2.13
  - primaryPreferred
```
@Deprecated
public static TaggableReadPreference primaryPreferred(DBObject firstTagSet,
                                                                  DBObject... remainingTagSets)
```
    Deprecated. use factory methods that take TagSet instead
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.
    
    See Also:
    
    primaryPreferred(TagSet), primaryPreferred(java.util.List)
  - secondary
```
@Deprecated
public static TaggableReadPreference secondary(DBObject firstTagSet,
                                                           DBObject... remainingTagSets)
```
    Deprecated. use factory methods that take TagSet instead
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    See Also:
    
    secondary(TagSet), secondary(java.util.List)
  - secondaryPreferred
```
@Deprecated
public static TaggableReadPreference secondaryPreferred(DBObject firstTagSet,
                                                                    DBObject... remainingTagSets)
```
    Deprecated. use factory methods that take TagSet instead
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    See Also:
    
    secondaryPreferred(TagSet), secondaryPreferred(java.util.List)
  - nearest
```
@Deprecated
public static TaggableReadPreference nearest(DBObject firstTagSet,
                                                         DBObject... remainingTagSets)
```
    Deprecated. use factory methods that take TagSet instead
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    See Also:
    
    nearest(TagSet), nearest(java.util.List)
  - valueOf
```
public static ReadPreference valueOf(java.lang.String name)
```
    Creates a read preference from the given read preference name.
    
    Parameters:
    
    name - the name of the read preference
    
    Returns:
    
    the read preference
  - valueOf
```
public static TaggableReadPreference valueOf(java.lang.String name,
                                             java.util.List<TagSet> tagSetList)
```
    Creates a taggable read preference from the given read preference name and list of tag sets.
    
    Parameters:
    
    name - the name of the read preference
    
    tagSetList - the list of tag sets
    
    Returns:
    
    the taggable read preference
    
    Since:
    
    2.13
  - valueOf
```
@Deprecated
public static TaggableReadPreference valueOf(java.lang.String name,
                                                         DBObject firstTagSet,
                                                         DBObject... remainingTagSets)
```
    Deprecated. use method that takes a List<TagSet>
    
    Creates a taggable read preference from the given read preference name and list of tag sets.
    
    Parameters:
    
    name - the name of the read preference
    
    firstTagSet - the first set of tags
    
    remainingTagSets - the remaining set of tags
    
    Returns:
    
    the taggable read preference
  - withTags
```
@Deprecated
public static ReadPreference withTags(java.util.Map<java.lang.String,java.lang.String> tags)
```
    Deprecated. As of release 2.9.0, replaced by ReadPreference.secondaryPreferred(DBObject firstTagSet, DBObject... remainingTagSets)
  - withTags
```
@Deprecated
public static ReadPreference withTags(DBObject tags)
```
    Deprecated. As of release 2.9.0, replaced by ReadPreference.secondaryPreferred(DBObject firstTagSet, DBObject... remainingTagSets)
  - toTagsList
```
private static java.util.List<TagSet> toTagsList(DBObject firstTagSet,
                                                 DBObject... remainingTagSets)
```
  - toTags
```
private static TagSet toTags(DBObject tagsDocument)
```

Class ReadPreference

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

PRIMARY

SECONDARY

_PRIMARY

_SECONDARY

_SECONDARY_PREFERRED

_PRIMARY_PREFERRED

_NEAREST

Constructor Detail

ReadPreference

Method Detail

isSlaveOk

toDBObject

getName

choose

primary

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

valueOf

valueOf

valueOf

withTags

withTags

toTagsList

toTags