org.datanucleus.store.rdbms.mapping

Class StatementClassMapping

java.lang.Object

org.datanucleus.store.rdbms.mapping.StatementClassMapping

public class StatementClassMapping
extends Object

Definition of statement mapping for a particular class. Provides a definition of how the results of a datastore query are mapped on to the fields of a class. If we take the example of this being the candidate class retrieved, then the memberName will be null and any children represent persistent objects also retrieved in this statement. So we process all fields in the result-set for this class, then instantiate any child object (with its id field(s)), and process all of its fields, etc.

We can have a result set with fields for multiple objects and instantiate more than 1 related object. To give an example of what an object of this type can look like

 StatementClassMapping:class=null,member=null,mappings=
 [
    {field=0,mapping=mapping: org.datanucleus.store.rdbms.mapping.IntegerMapping@5995c31c column(s): [2]},
    {field=1,mapping=mapping: org.datanucleus.store.rdbms.mapping.PersistableMapping@5947d51d column(s): [3]},
    {field=2,mapping=mapping: org.datanucleus.store.rdbms.mapping.PersistableMapping@585e7d87 column(s): [7]},
    {field=-2,mapping=mapping: org.datanucleus.store.rdbms.mapping.VersionLongMapping@ce796 column(s): [11]},
 ],
 children=
 [
    {field=1,mapping=StatementClassMapping:class=org.datanucleus.test.CircRef,member=next,mappings=
       [
            {field=0,mapping=mapping: org.datanucleus.store.rdbms.mapping.IntegerMapping@5995c31c column(s): [3]},
            {field=1,mapping=mapping: org.datanucleus.store.rdbms.mapping.PersistableMapping@5947d51d column(s): [4]},
            {field=2,mapping=mapping: org.datanucleus.store.rdbms.mapping.PersistableMapping@585e7d87 column(s): [5]},
            {field=-2,mapping=mapping: org.datanucleus.store.rdbms.mapping.VersionLongMapping@ce796 column(s): [6]}
        ]},
    {field=2,mapping=StatementClassMapping:class=org.datanucleus.test.CircRef,member=prev,mappings=
        [
            {field=0,mapping=mapping: org.datanucleus.store.rdbms.mapping.IntegerMapping@5995c31c column(s): [7]},
            {field=1,mapping=mapping: org.datanucleus.store.rdbms.mapping.PersistableMapping@5947d51d column(s): [8]},
            {field=2,mapping=mapping: org.datanucleus.store.rdbms.mapping.PersistableMapping@585e7d87 column(s): [9]},
            {field=-2,mapping=mapping: org.datanucleus.store.rdbms.mapping.VersionLongMapping@ce796 column(s): [10]}
        ]}
 ]

In this example we have a persistable object as candidate, and it has 2 1-1 relations (field=1, field=2). These are both being retrieved in the same query, hence the sub-mappings. Note that the column(s) of the FK in the owner object is the same as the PK field(s) of the related object.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MEMBER_DATASTORE_ID
static int	MEMBER_DISCRIMINATOR
static int	MEMBER_VERSION

Constructor Summary

Constructors

Constructor and Description
StatementClassMapping()
StatementClassMapping(String className, String memberName)

Method Summary

Modifier and Type	Method and Description
void	addMappingDefinitionForMember(int position, StatementClassMapping defn)
void	addMappingForMember(int position, StatementMappingIndex mapping)
StatementClassMapping	cloneStatementMappingWithoutChildren()
String	getClassName()
StatementClassMapping	getMappingDefinitionForMemberPosition(int position) Accessor for the mapping definition for the object at the specified member position.
StatementMappingIndex	getMappingForMemberPosition(int position) Accessor for the mapping information for the member at the specified position.
String	getMemberName()
int[]	getMemberNumbers() Accessor for the numbers of the members present.
String	getNucleusTypeColumnName()
boolean	hasChildMappingDefinitions() Accessor for whether this definition has child object definitions.
void	setNucleusTypeColumnName(String colName)
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

MEMBER_DATASTORE_ID

public static final int MEMBER_DATASTORE_ID

See Also:

Constant Field Values

MEMBER_VERSION

public static final int MEMBER_VERSION

See Also:

Constant Field Values

MEMBER_DISCRIMINATOR

public static final int MEMBER_DISCRIMINATOR

See Also:

Constant Field Values

Constructor Detail

StatementClassMapping

public StatementClassMapping()

StatementClassMapping

public StatementClassMapping(String className,
                             String memberName)

Method Detail

getClassName

public String getClassName()

getMemberName

public String getMemberName()

setNucleusTypeColumnName

public void setNucleusTypeColumnName(String colName)

getNucleusTypeColumnName

public String getNucleusTypeColumnName()

getMappingForMemberPosition

public StatementMappingIndex getMappingForMemberPosition(int position)

Accessor for the mapping information for the member at the specified position. Member positions start at 0 (first member in the root persistent class). Member position of -1 means datastore-identity. Member position of -2 means version. Member position of -3 means discriminator.

Parameters:

position - The member position

Returns:

The mapping information

getMappingDefinitionForMemberPosition

public StatementClassMapping getMappingDefinitionForMemberPosition(int position)

Accessor for the mapping definition for the object at the specified member position. Returns null if the member is not a relation field. Member positions start at 0 (first member in the root persistent class). Member position of -1 means datastore-identity. Member position of -2 means version. Member position of -3 means discriminator.

Parameters:

position - The position of the member in this class

Returns:

The mapping definition for the object at this member position

hasChildMappingDefinitions

public boolean hasChildMappingDefinitions()

Accessor for whether this definition has child object definitions.

Returns:

Whether there are sub-objects of this object mapped.

getMemberNumbers

public int[] getMemberNumbers()

Accessor for the numbers of the members present. Doesn't include any surrogate numbers since not real members.

Returns:

The member positions

addMappingForMember

public void addMappingForMember(int position,
                                StatementMappingIndex mapping)

addMappingDefinitionForMember

public void addMappingDefinitionForMember(int position,
                                          StatementClassMapping defn)

cloneStatementMappingWithoutChildren

public StatementClassMapping cloneStatementMappingWithoutChildren()

toString

public String toString()

Overrides:

toString in class Object