Package com.streambase.sb

Class Schema.Field

java.lang.Object

com.streambase.sb.Schema.Field

All Implemented Interfaces:

Serializable

Enclosing class:

Schema

public static class Schema.Field
extends Object
implements Serializable

Information (name, type, and optionally size) about a field in a Schema.

A field can be looked up within a schema in three ways:

1. By index: By the zero-based ordinal position of the field within the schema
2. By simple name: By the name of the field itself (e.g., "myint")
3. By path name: By a dot-separated list of names that define a path through a set of nested schemas that arise through the use of fields of type Tuple (e.g., "mynestedtuple.myint").

A Field object can be used to obtain the value of a field in a tuple. However, there are rules that must be obeyed in doing so. For example, one must obtain the Field object from a Schema object that describes the schema of the tuple (i.e., as opposed to directly from a Field constructor).

See the "client" StreamBase sample (streambase-install-dir/sample/client) for examples of proper use of Field objects.

Note: Serializations of instances of this class that are created (e.g., by using ObjectOutputStream) in one version of StreamBase in general will not be deserializable in any other version of StreamBase.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
Field(Schema.Field field)	Construct a Field from an existing Field.
Field(String name, CompleteDataType completeType, com.streambase.sb.util.Location loc)	Constructor
Field(String name, DataType dataType)	Deprecated. Use Schema.createField(DataType, String) instead
Field(String name, DataType dataType, Schema s)	Deprecated. Use Field(String, CompleteDataType) instead with new Schema(name, CompleteDataType.forTuple(s)), or Schema.createTupleField(String, Schema)
Field(String name, Schema.Field field)	Construct a Field from an existing Field, giving the new field a specified name

Method Summary

Modifier and Type	Method	Description
void	checkType(CompleteDataType dataType)	Check to make sure that the given type is the same as the type of this Field
void	checkType(DataType dataType)	Deprecated. Use checkType(CompleteDataType)
boolean	equalsNoCapture(Schema.Field other)	Compare non-capture fields
CompleteDataType	getCompleteDataType()	Return the CompleteDataType of the Field
DataType	getDataType()	Return the DataType of the Field
String	getDescription()	Returns the description currently set for this field.
CompleteDataType	getElementType()	Return the element type for this field.
int	getIndex()	Return the index of this field within the Schema
com.streambase.sb.util.Location	getLocation()	Get location
String	getName()	Return the name of the Field.
Schema.Field	getNestedField(String fieldPathName)	Return a field that identifies a field in a nested tuple field.
Schema.Field[]	getNestedFields()	Return an array of fields, each of which identifies a field in a nested tuple field.
Schema	getSchema()	Return the schema for this field.
String	getShortName()	Return the last (which might be the only) segment of this Field
int	getSize()	Return the size of the field (in bytes) without any header information.
void	setDescription(String description)	Sets this field's description.
String	toString()	Return a String representation of this field.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

Field

public Field(String name,
 CompleteDataType completeType,
 com.streambase.sb.util.Location loc)

Constructor

Parameters:

name - Field name

completeType - Field data type

loc - Source location

Field

public Field(Schema.Field field)

Construct a Field from an existing Field.

Parameters:

field - Field to copy data from

Field

public Field(String name,
 Schema.Field field)

Construct a Field from an existing Field, giving the new field a specified name

Parameters:

name - The name of the field

field - Field to copy data from

Field

@Deprecated
public Field(String name,
 DataType dataType)

Deprecated.

Use Schema.createField(DataType, String) instead

Construct a Field of a specified type, giving the new field a specified name.

Parameters:

name - The name of the Field

dataType - The DataType of the Field

Throws:

IllegalArgumentException - if dataType requires a schema or an element type

Field

@Deprecated
public Field(String name,
 DataType dataType,
 Schema s)

Deprecated.

Use Field(String, CompleteDataType) instead with new Schema(name, CompleteDataType.forTuple(s)), or Schema.createTupleField(String, Schema)

Construct a Field of a specified type and bound to a specified schema, giving the new field a specified name.

Parameters:

name - The name of the Field

dataType - The DataType of the Field

s - The schema of the Field

Throws:

IllegalArgumentException - if dataType doesn't require a schema or requires an element type

Method Details

getLocation

public com.streambase.sb.util.Location getLocation()

Get location

Returns:

Location

equalsNoCapture

public boolean equalsNoCapture(Schema.Field other)

Compare non-capture fields

Parameters:

other - Compare with this field

Returns:

true if equal

checkType

@Deprecated
public void checkType(DataType dataType)
               throws TupleException

Deprecated.

Use checkType(CompleteDataType)

Check to make sure that the given type is the same as the type of this Field

Parameters:

dataType - The DataType to check

Throws:

TupleException - thrown when the types do not match

checkType

public void checkType(CompleteDataType dataType)
               throws TupleException

Check to make sure that the given type is the same as the type of this Field

Parameters:

dataType - The CompleteDataType to check

Throws:

TupleException - thrown when the types do not match

Since:

6.3.7

getDataType

public DataType getDataType()

Return the DataType of the Field

Returns:

DataType of the Field

getCompleteDataType

public CompleteDataType getCompleteDataType()

Return the CompleteDataType of the Field

Returns:

CompleteDataType of the Field

Since:

6.3

getName

public String getName()

Return the name of the Field. If the Field was constructed from a field path name, that path name is returned

Returns:

The name of the Field

getShortName

public String getShortName()

Return the last (which might be the only) segment of this Field

Returns:

the last segment of this Field

getIndex

public int getIndex()

Return the index of this field within the Schema

Returns:

The index of the field within the Schema

getSize

public int getSize()

Return the size of the field (in bytes) without any header information.

Returns:

The size of the Field in bytes (without header information)

getSchema

public Schema getSchema()

Return the schema for this field. Valid only if the type of the field is Tuple.

Returns:

The schema, or null if field type is not Tuple

Since:

6.0

getNestedField

public Schema.Field getNestedField(String fieldPathName)
                            throws TupleException

Return a field that identifies a field in a nested tuple field. This method can be applied only to a field whose type is Tuple.

Parameters:

fieldPathName - the path name to the desired nested tuple field

Returns:

the field

Throws:

TupleException - if the field path name is invalid or this field isn't of type Tuple

Since:

6.0

getNestedFields

public Schema.Field[] getNestedFields()
                               throws TupleException

Return an array of fields, each of which identifies a field in a nested tuple field. This method can be applied only to a field whose type is Tuple.

Returns:

the array of fields

Throws:

TupleException - if this field is not of type Tuple.

Since:

6.0

toString

public String toString()

Return a String representation of this field.

Overrides:

toString in class Object

Returns:

String representation of this Field

getDescription

public String getDescription()

Returns the description currently set for this field. At runtime this method will return null, and the description can only be guaranteed to have meaning during application development in the authoring environment.

Returns:

this field's description String null when unknown

setDescription

public void setDescription(String description)

Sets this field's description.

Parameters:

description - the description String for this field

getElementType

public CompleteDataType getElementType()

Return the element type for this field. Valid only if the type of the field is List.

Returns:

The schema, or null if field type is not List

Since:

6.3