ReferenceValue#

public class ReferenceValue implements SingleValue#

A ReferenceValue represents the value of a reference property to another entity.

Differently from other properties, they may be versioned, i.e. they may reference to a specific version of an entity.

Ways to specify a reference value: {id}@{version} using either the version id (a hex’ed sha256 string) or “HEAD”, “HEAD~1”, “HEAD~2” and so on. Note: “HEAD” always means the “HEAD” after the transaction. So, if you are changing the referenced entity in the same transaction and you want to reference the entity in the version before the change you need to use “HEAD~1” because that is the old version of the future.

Author:

Timm Fitschen

Constructors#

ReferenceValue#

public ReferenceValue(EntityInterface entity, boolean versioned)#

ReferenceValue#

public ReferenceValue(EntityID id)#

ReferenceValue#

public ReferenceValue(EntityID id, String version)#

ReferenceValue#

public ReferenceValue(String name)#

If the reference is given by name, versioning is not possible (at the moment).

ReferenceValue#

public ReferenceValue(String name, String version)#

Methods#

addToElement#

public void addToElement(Element e)#

equals#

public boolean equals(Object obj)#

equals#

public boolean equals(Value val)#

Test if this is equal to the other object.

Two references are equal, if 1) they both have IDs and their content is equal or 2) at least one does not have an ID, but their names are equal. Otherwise they are considered unequal.

Parameters:

  • val – The other object.

getEntity#

public final EntityInterface getEntity()#

getId#

public final EntityID getId()#

getIdVersion#

public String getIdVersion()#

getName#

public final String getName()#

getTable#

public Table getTable()#

getVersion#

public final String getVersion()#

parseFromString#

public static ReferenceValue parseFromString(String str)#

Create a ReferenceValue from a string.

If the string looks like a valid “entityID@version” string, the result will have the corresponding entity and version parts.

parseIdVersion#

public static ReferenceValue parseIdVersion(String str)#

Split a reference string into an entity part and a version part, if there is a version part.

If parsing the entity ID part to an integer fails, a NumberFormatException may be thrown.

parseReference#

public static ReferenceValue parseReference(EntityID reference)#

parseReference#

public static ReferenceValue parseReference(Object reference)#

setEntity#

public final void setEntity(EntityInterface entity, boolean versioned)#

setId#

public final void setId(EntityID id)#

setName#

public void setName(String name)#

toDatabaseString#

public String toDatabaseString()#

toString#

public String toString()#

Produce a nice but short string:

Case 1 “versioned” (reference to an entity without specifying that entity’s version): Produces a string like “1234” or “Experiment”. Note that referencing via name is never versioned.

Case 2 “unversioned” (reference to an entity with a specified version): Produces a string like “1234@ab987f”.