prajna.data.field

Class FieldDesc<T>

java.lang.Object

prajna.data.field.FieldDesc<T>

Type Parameters:

T - The data type this field definition represents

All Implemented Interfaces:

java.io.Serializable, Xmlizable

Direct Known Subclasses:

BooleanFieldDesc, EnumFieldDesc, GeoFieldDesc, IntFieldDesc, LocationFieldDesc, LongFieldDesc, MeasureFieldDesc, TextFieldDesc, TimeFieldDesc, TokenFieldDesc, UrlFieldDesc

public abstract class FieldDesc<T>
extends java.lang.Object
implements java.io.Serializable, Xmlizable

Description of a field of a DataTemplate or other class. The field description class provides a definition and description of the fields for a data template. The field description includes the field name, default values, acceptable values, and parsing support.

Author:

Edward Swing

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
FieldDesc()

Method Summary

Methods

Modifier and Type	Method and Description
void	addSourceField(java.lang.String srcField) Add a field to the set of source fields for this descriptor
java.lang.String	applyTransform(java.lang.String value) Applies the String transformation to the field value.
T	getDefaultValue() Get the default value for this field description
java.lang.String	getFieldName() Get the name of the field
abstract DataType	getFieldType() Get the field type for this field description
java.lang.String	getLookupIndexField() Get the name of the field used as the index field in the lookup table.
java.lang.String	getLookupTable() Get the name of the table used to look up indexed values.
java.lang.String	getLookupValueField() Get the name of the field used to contain the values which correspond to the keys.
java.util.Set<java.lang.String>	getSourceFields() Get the source fields for the field.
StringTransform	getTransform() Get the transform, if any, for this descriptor
boolean	isMultiValue() Return whether this field can have multiple values, or only one value
abstract boolean	isValid(T value) Determine whether a particular field is valid for this field definition.
void	loadFromXml(org.w3c.dom.Element elem) Load the field description from XML.
abstract T	parse(java.lang.String stringVal) Parse the string value into a value handled by this field description The parse method does not perform any form of validation other than to convert the string into the appropriate data type.
abstract T	parseValueIntoRecord(DataRecord rec, java.lang.String value) Parse the string value, and store it in the appropriate record field in the specified data record.
void	setDefaultValue(T value) Set the default value for this field description
protected void	setFieldName(java.lang.String name) Set the field name.
void	setMultiValue(boolean multiFlag) Set whether this field is a multi-valued field
protected abstract void	setValues(org.w3c.dom.NodeList valueList) Set the values according to the series of elements specified by the values tag in the corresponding XML Document.
abstract void	storeDefaultIntoRecord(DataRecord rec) Store the default value into the data record provided.
abstract org.w3c.dom.Element	toXml(org.w3c.dom.Document doc) Convert this field definition to XML format.

Methods inherited from class java.lang.Object

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

Constructor Detail

FieldDesc

public FieldDesc()

Method Detail

addSourceField

public void addSourceField(java.lang.String srcField)

Add a field to the set of source fields for this descriptor

Parameters:

srcField - the new source field

applyTransform

public java.lang.String applyTransform(java.lang.String value)

Applies the String transformation to the field value.

Parameters:

value - the text field value

Returns:

the transformed field string

getDefaultValue

public T getDefaultValue()

Get the default value for this field description

Returns:

the default value

getFieldName

public java.lang.String getFieldName()

Get the name of the field

Returns:

the field name

getFieldType

public abstract DataType getFieldType()

Get the field type for this field description

Returns:

the field type

getLookupIndexField

public java.lang.String getLookupIndexField()

Get the name of the field used as the index field in the lookup table. This corresponds to the key for the table which references the values in the database. This method is only needed for databases which use indexed values and normal forms.

Returns:

the lookup table index

getLookupTable

public java.lang.String getLookupTable()

Get the name of the table used to look up indexed values. This method is only needed for databases which use indexed values and normal forms.

Returns:

the lookup table name

getLookupValueField

public java.lang.String getLookupValueField()

Get the name of the field used to contain the values which correspond to the keys. This method is only needed for databases which use indexed values and normal forms.

Returns:

the lookupValue

getSourceFields

public java.util.Set<java.lang.String> getSourceFields()

Get the source fields for the field. The source fields are the field name in the underlying data source. Most field accessors will typically have one source field. However, multiple source fields may be necessary for a few applications.

Returns:

the set of source field

getTransform

public StringTransform getTransform()

Get the transform, if any, for this descriptor

Returns:

the transform, or null if no transform has been set

isMultiValue

public boolean isMultiValue()

Return whether this field can have multiple values, or only one value

Returns:

true if the field can take multiple values, false if it can only take a single value.

isValid

public abstract boolean isValid(T value)

Determine whether a particular field is valid for this field definition. This method checks the allowed values for this field description to determine if the value is valid

Parameters:

value - the value for the field

Returns:

true if the value is valid, false otherwise

loadFromXml

public void loadFromXml(org.w3c.dom.Element elem)

Load the field description from XML. This method reads the element, extracting the fieldName attribute for the field name, and the sourceField attribute for the source field. If the sourceField attribute is not set, the source field is set to the field name. This method then extracts the optional child element with the tag name values to identify the valid values. It passes the children of the values element to the setValues() method. The method then extracts the optional default value, and parses it if present.

Specified by:

loadFromXml in interface Xmlizable

Parameters:

elem - the field description element

parse

public abstract T parse(java.lang.String stringVal)
                 throws java.text.ParseException

Parse the string value into a value handled by this field description The parse method does not perform any form of validation other than to convert the string into the appropriate data type.

Parameters:

stringVal - the String value to parse

Returns:

the parsed value

Throws:

java.text.ParseException - if there is a problem parsing the string

parseValueIntoRecord

public abstract T parseValueIntoRecord(DataRecord rec,
                     java.lang.String value)
                                throws java.text.ParseException

Parse the string value, and store it in the appropriate record field in the specified data record. The value will be parsed, and then the appropriate setTYPEField will be invoked on the record with the result of the parse. If there is a problem parsing, this method should throw a ParseException.

Parameters:

rec - the DataRecord to parse the value into

value - the String value to be parsed

Returns:

the value object added

Throws:

java.text.ParseException - if there is a problem parsing the string

java.lang.IllegalArgumentException - if the value is not valid

setDefaultValue

public void setDefaultValue(T value)

Set the default value for this field description

Parameters:

value - the default value

setFieldName

protected void setFieldName(java.lang.String name)

Set the field name.

Parameters:

name - the field name

setMultiValue

public void setMultiValue(boolean multiFlag)

Set whether this field is a multi-valued field

Parameters:

multiFlag - true if the field allows multiple values, false otherwise

setValues

protected abstract void setValues(org.w3c.dom.NodeList valueList)

Set the values according to the series of elements specified by the values tag in the corresponding XML Document.

Parameters:

valueList - list of nodes. This should be the child nodes of the values element for this attribute declaration.

storeDefaultIntoRecord

public abstract void storeDefaultIntoRecord(DataRecord rec)

Store the default value into the data record provided. If the default value is null, no action is taken.

Parameters:

rec - the DataRecord to store the value into

toXml

public abstract org.w3c.dom.Element toXml(org.w3c.dom.Document doc)

Convert this field definition to XML format. This method builds the XML element to add to the XML document provided. The XML produced should be of the same format that loadFromXml reads.

Specified by:

toXml in interface Xmlizable

Parameters:

doc - the XML document

Returns:

the new element for this field description