com.redhat.lightblue.query

Class Projection

java.lang.Object

com.redhat.lightblue.util.JsonObject

com.redhat.lightblue.query.Projection

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

BasicProjection, ProjectionList

public abstract class Projection
extends JsonObject

Base class for all projection objects

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type

Class and Description

static class

Projection.Inclusion Inclusion status for a field explicit_exclusion: the projection excludes this field explicitly implicit_exzclusion: the projection excludes this field because an ancestor of the field is excluded explicit_inclusion: the projection includes the field explicitly explicit_exclusion: the projection excludes the field explicitly undecided: the projection does not decide if the field should be included/excluded, and does not reference it

Constructor Summary

Constructors

Constructor and Description
Projection()

Method Summary

Methods

Modifier and Type	Method and Description
static Projection	add(Projection p1, Projection p2) Adds two projections and returns a new projection containing both.
static Boolean	fieldAncestorOfPattern(Path field, Path pattern, boolean inclusion) If the field is an ancestor of the pattern, and if inclusion is true, returns true.
static Boolean	fieldMatchesPattern(Path field, Path pattern, boolean inclusion) Returns whether to include/exclude the field based on whether the field matches the pattern
static Projection	fromJson(com.fasterxml.jackson.databind.JsonNode node)
Projection.Inclusion	getFieldInclusion(Path field) Determines if the field is included in this projection
Projection.Inclusion	getFieldInclusion(Path field, Path ctx) Determine if the field is explicitly included/excluded, implicitly included, or the projection does not decide on the field.
protected static Path	getNonRelativePath(Path p)
static Boolean	impliedInclusion(Path field, Path pattern, boolean inclusion) Returns if the field should be included based on the recursive pattern.
static Projection.Inclusion	isFieldIncluded(Path field, Path pattern, boolean inclusion, boolean recursive) Returns if the field should be included based on the pattern given.
boolean	isFieldRequiredToEvaluateProjection(Path field) Returns true if the field is needed to evaluate the projection
boolean	isFieldRequiredToEvaluateProjection(Path field, Path ctx) Returns true if the field is needed to evaluate the projection

Methods inherited from class com.redhat.lightblue.util.JsonObject

getFactory, getSourceNode, toJson, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Projection

public Projection()

Method Detail

fromJson

public static Projection fromJson(com.fasterxml.jackson.databind.JsonNode node)

add

public static Projection add(Projection p1,
             Projection p2)

Adds two projections and returns a new projection containing both. Any projection can be null. If the resulting projection is empty, returns null.

fieldMatchesPattern

public static Boolean fieldMatchesPattern(Path field,
                          Path pattern,
                          boolean inclusion)

Returns whether to include/exclude the field based on whether the field matches the pattern

Parameters:

field - The field name

pattern - The projection pattern

inclusion - flag to return if the field matches the given pattern

Returns:

value of inclusion if field matches the pattern, else null

     field    pattern   result
      a          *       true
      a          a       true
      a          b       false
      a.b        *       false
      a.b       *.b      true
      a.b       a.*      true
      a.b       *.*      true
      a.b       a.b      true
 

The return value is inclusion if result is true, null if result is false, meaning that whether the field should be included or not cannot be decided.

fieldAncestorOfPattern

public static Boolean fieldAncestorOfPattern(Path field,
                             Path pattern,
                             boolean inclusion)

If the field is an ancestor of the pattern, and if inclusion is true, returns true. Otherwise, returns null, meaning that whether the field is included or not cannot be decided.

Parameters:

field - The field name

pattern - The projection pattern

inclusion - flag to return if the field matches the given pattern

Returns:

TRUE if field is ancestor of the pattern and inclusion is true, else null

impliedInclusion

public static Boolean impliedInclusion(Path field,
                       Path pattern,
                       boolean inclusion)

Returns if the field should be included based on the recursive pattern.

Parameters:

field - The field name

pattern - The projection pattern

inclusion - flag to return if the field matches the given pattern

Returns:

Boolean value of inclusion if field is in subtree of pattern else null

isFieldIncluded

public static Projection.Inclusion isFieldIncluded(Path field,
                                   Path pattern,
                                   boolean inclusion,
                                   boolean recursive)

Returns if the field should be included based on the pattern given.

Parameters:

field - The field whose inclusion is to be decided

pattern - The field pattern of projection

inclusion - If the projection expression includes the field. If false, the projection is for exclusion

recursive - If the projection is recursive

Returns:

implicit or explicit inclusion/exclusion, or undecided if projection does not decide if the field should be included/excluded

getFieldInclusion

public Projection.Inclusion getFieldInclusion(Path field)

Determines if the field is included in this projection

Parameters:

field - The absolute name of the field If the field name contains array indexes, they are converted to '*' before evaluation.

getFieldInclusion

public Projection.Inclusion getFieldInclusion(Path field,
                                     Path ctx)

Determine if the field is explicitly included/excluded, implicitly included, or the projection does not decide on the field.

isFieldRequiredToEvaluateProjection

public boolean isFieldRequiredToEvaluateProjection(Path field)

Returns true if the field is needed to evaluate the projection

isFieldRequiredToEvaluateProjection

public boolean isFieldRequiredToEvaluateProjection(Path field,
                                          Path ctx)

Returns true if the field is needed to evaluate the projection

getNonRelativePath

protected static Path getNonRelativePath(Path p)