JavaBeanReader

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Short Description

JavaBeanReader reads a JavaBeans hierarchical structure which is stored in a dictionary. That allows dynamic data interchange between Clover graphs and external environment, such as cloud. The dictionary you are reading to serves as an interface between the outer (e.g. cloud) and inner worlds (Clover).

Component	Data source	Input ports	Output ports	Each to all outputs	Different to different outputs	Transformation	Transf. req.	Java	CTL	Auto-propagated metadata
JavaBeanReader	dictionary	0	1-n

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Ports

Port type	Number	Required	Description	Metadata
Output	0		Successfully read records.	Any
Output	1-n	Connect other output ports if your mapping requires that.	Successfully read records.	Any. Each port can have different metadata.

Metadata

JavaBeanReader does not propagate metadata.

JavaBeanReader has no metadata template.

JavaBeanReader Attributes

Attribute	Req	Description	Possible values
Basic
Dictionary source	yes	The dictionary you want to read JavaBeans from.	Name of a dictionary you have previously defined.
Data policy		Determines what should be done when an error on reading occurs. See Data Policy for more information.	Strict (default) \| Controlled \| Lenient
Mapping	^[1]	Mapping the input JavaBeans structure to output ports. See JavaBeanReader Mapping Definition for more information.
Mapping URL	^[1]	External text file containing the mapping definition.
Implicit mapping		By default, you have to manually map input elements even to Clover fields of the same name. If you switch to `true`, JSON-to-Clover mapping on matching names will be performed automatically. That can save you a lot of effort in long and well-structured JSON files. See JSON Mapping - Specifics.	false (default) \| true
^[1] One of these has to be specified. If both are specified, Mapping URL has a higher priority.

Details

JavaBeanReader reads data from JavaBeans through a dictionary. It maps Java attributes / collection elements to output records based on a mapping you define. You do not have to map the whole input file - you use XPath expressions to select only the data you need. The component sends data to different connected output records as defined by your mapping.

The mapping process is similar to the one in XMLReader.

JavaBeanReader Mapping Definition

Every Mapping definition consists of <Context> tags which contain also some attributes and allow mapping of element names to Clover fields. Nested structure of <Context> tags is similar to the nested structure of elements in input JavaBeans.
Each <Context> tag can surround a serie of nested <Mapping> tags. These allow to rename JavaBeans elements to Clover fields. However, Mapping does not need to copy the whole input structure, it can start at an arbitrary depth in the tree.

Each of these <Context> and <Mapping> tags contains some JavaBeanReader Context Tag Attributes and JavaBeanReader Mapping Tag Attributes, respectively.

Example 53.4. Example Mapping in JavaBeanReader

    
	<Context xpath="/employees" outPort="0" sequenceId="empSeq" sequenceField="id">
		<Mapping xpath="firstName" cloverField="firstName"/>
		<Mapping xpath="lastName" cloverField="lastName"/>
		<Mapping xpath="salary" cloverField="salary"/>
		<Mapping xpath="jobTitle" cloverField="jobTitle"/>
		<Context xpath="children" outPort="1" parentKey="id" generatedKey="empID">
			<Mapping xpath="name" cloverField="chname"/>
			<Mapping xpath="age" cloverField="age"/>
		</Context>
		<Context xpath="benefits" outPort="2" parentKey="id" generatedKey="empID">
			<Mapping xpath="car" cloverField="car"/>
			<Mapping xpath="cellPhone" cloverField="mobilephone"/>
			<Mapping xpath="monthlyBonus" cloverField="monthlyBonus"/>
			<Mapping xpath="yearlyBonus" cloverField="yearlyBonus"/>
		</Context>
		<Context xpath="projects" outPort="3" parentKey="id" generatedKey="empID">
			<Mapping xpath="name" cloverField="projName"/>
			<Mapping xpath="manager" cloverField="projManager"/>
			<Mapping xpath="start" cloverField="Start"/>
			<Mapping xpath="end" cloverField="End"/>
			<Mapping xpath="customers" cloverField="customers"/>
		</Context>
	</Context>

Important

	Important
If you switch Implicit mapping to `true`, elements (e.g. `salary`) will be automatically mapped onto fields of the same name (`salary`) and you do not have to write: <Mapping xpath="salary" cloverField="salary"/> and you map explicitly only to populate fields with data from distinct elements.

If you switch Implicit mapping to true, elements (e.g. salary) will be automatically mapped onto fields of the same name (salary) and you do not have to write:

	    	
	    	<Mapping xpath="salary" cloverField="salary"/>

and you map explicitly only to populate fields with data from distinct elements.

JavaBeanReader Context Tags and Mapping Tags
- Empty Context Tag (Without a Child)
  <Context xpath="xpathexpression" JavaBeanReader Context Tag Attributes />
- Non-Empty Context Tag (Parent with a Child)
  <Context xpath="xpathexpression" JavaBeanReader Context Tag Attributes >
  (nested Context and Mapping elements (only children, parents with one or more children, etc.)
  </Context>
- Empty Mapping Tag (Renaming Tag)
  - xpath is used:
    <Mapping xpath="xpathexpression" JavaBeanReader Mapping Tag Attributes />
  - nodeName is used:
    <Mapping nodeName="elementname" JavaBeanReader Mapping Tag Attributes />
JavaBeanReader Context Tag and Mapping Tag Attributes
1) JavaBeanReader Context Tag Attributes
- xpath
  Required
  The xpath expression can be any XPath query.
  Example: xpath="/tagA/.../tagJ"
- outPort
  Optional
  Number of output port to which data is sent. If not defined, no data from this level of Mapping is sent out using such level of Mapping.
  Example: outPort="2"
- parentKey
  Both parentKey and generatedKey must be specified.
  Sequence of metadata fields on the next parent level separated by semicolon, colon, or pipe. Number and data types of all these fields must be the same in the generatedKey attribute or all values are concatenated to create a unique string value. In such a case, key has only one field.
  Example: parentKey="first_name;last_name"
  Equal values of these attributes assure that such records can be joined in the future.
- generatedKey
  Both parentKey and generatedKey must be specified.
  Sequence of metadata fields on the specified level separated by semicolon, colon, or pipe. Number and data types of all these fields must be the same in the parentKey attribute or all values are concatenated to create a unique string value. In such a case, key has only one field.
  Example: generatedKey="f_name;l_name"
  Equal values of these attributes assure that such records can be joined in the future.
- sequenceId
  When a pair of parentKey and generatedKey does not insure unique identification of records, a sequence can be defined and used.
  Id of the sequence.
  Example: sequenceId="Sequence0"
- sequenceField
  When a pair of parentKey and generatedKey does not insure unique identification of records, a sequence can be defined and used.
  A metadata field on the specified level in which the sequence values are written. Can serve as parentKey for the next nested level.
  Example: sequenceField="sequenceKey"
2) JavaBeanReader Mapping Tag Attributes
- xpath
  Either xpath or nodeName must be specified in <Mapping> tag.
  XPath query.
  Example: xpath="tagA/.../salary"
- nodeName
  Either xpath or nodeName must be specified in <Mapping> tag. Using nodeName is faster than using xpath.
  JavaBeans node that should be mapped to Clover field.
  Example: nodeName="salary"
- cloverField
  Required
  Clover field to which JavaBeans node should be mapped.
  Name of the field in the corresponding level.
  Example: cloverFields="SALARY"

Reading Multivalue Fields

As of Clover 3.3, reading multivalue fields is supported - you can read only lists, however (see Multivalue Fields).

	Note
	Reading maps is handled as reading pure `string` (for all data types as map's values).

Example 53.5. Reading lists with JavaBeanReader

An example input file containing e.g. a list of three elements: John, Vicky, Brian

can be read back by the component with this mapping:

    
    <Mapping xpath="attendees" cloverField="attendanceList"/>

where attendanceList is a field of your metadata. The metadata has to be assigned to the component's output edge. After you run the graph, the field will get populated by data like this (that what you will see in View data):

[John,Vicky,Brian]

Data conversions in JavaBeanReader

The possible conversions of java data types to CTL2 data types are described in the following table.

The list in the table means list of corresponding data type.

Table 53.6. Java data type to CTL2 data type conversion

Java data types	CTL2 data types
	Numeric data types				boolean	date	byte	cbyte	String	list	map
	integer	long	number (double)	decimal	boolean	date	byte	cbyte	String	list	map
int					-		-	-
long	-			-	-		-	-
float	-	-		-			-	-
double	-	-		-			-	-
boolean							-	-
java.util.Date							-	-
String	-	-	-	-	-		-	-
array []	-	-	-	-	-		-	-	-	-
java.util.Collection	-	-	-	-	-		-	-	-

Conversions need to be explained follow:

Java int to CTL2 boolean

Value 0 is converted to false, 1 is converted to true. If java int contains other value, graph fails.

Java int to CTL2 byte or cbyte

Value of int variable is converted either to character or to empty string.

Java long to CTL2 integer

Value of java bean long variable can be read to integer field provided the value is within the range of CTL2 integer. If the value is out of the range of CTL2 integer, graph fails.

Java long to CTL2 decimal

The decimal needs to have sufficient length to contain value from long data type. The default length (12) might not be enough for all cases.

Java long to CTL2 boolean

The conversion from java long to CTL2 boolean works in the same way as conversion from java int to CTL2 boolean. 0 is converted to false, 1 is converted to true, other values cause failure.

Java long to CTL2 byte or cbyte

See: Java int to CTL2 byte or cbyte conversion.

Java float to CTL2 integer

Value of java float variable can be converted to CTL2 integer. Value of the float number is being truncated in the conversion. If the value in float variable is out of the range of integer, conversion fails.

Java float to CTL2 long

Value of java float variable can be converted to CTL2 long. The value of float number is being truncated. If the value stored in float variable is positive and out of the range of long data type, the nearest long value is used. If the value stored in float variable is negative and out of the range of long data type, the result is null.

Java float to CTL2 decimal

CTL2 decimal needs to have sufficient length. If not, the conversion from java float fails.

Java float to CTL2 byte and cbyte

Value of java float is trimmed to it's integral part and the result value is converted to character. If the value is out of the range of byte, empty string is used.

Java double to CTL2 integer

Value of java double needs to be within the range of CTL2 integer. The value of java double is truncated to it's integral part towards zero. If the value is out of the range, conversion fails.

Java double to CTL2 long

If the value of java doubleis within the range of CTL2 long, the value is truncated to nearest integral value towards zero. If the value of java double is positive and out of the range of CTL2 long, the result is the largest long number (Long.MAX_VALUE). If the value of java double is negative and out of the range of CTL long, the result is null.

Java double to CTL2 decimal

The CTL2 decimal needs to have sufficient length to contain value of java double. In case of insufficient length of CTL2 decimal the conversion fails.

Java double to CTL2 byte and cbyte

Value of java double is trimmed to it's integral part and the result is converted to character. If the value is out of the range of byte, empty string is used.

Java boolean to CTL2 byte and cbyte

Value of java boolean converted to CTL2 byte or cbyte is single unprintable character. The character has code 0 if the input is false or 1 if the input is true.

Java Date to CTL2 byte and cbyte

Value of java Date converted to byte or cbyte results in empty string.

Java String to CTL2 integer or long

If the java String variable contains integral value within the range of integer, the number will be converted. Otherwise conversion fails.

If the java String variable contains integral value within the range of long, the number will be converted to the long. Otherwise conversion fails.

Java String to CTL2 number (double) or decimal

If the java string contains numeric value, the value is converted to number (double) or decimal. If the java string does not contain numeric value, the conversion fails.

Java String to CTL2 boolean

If java String contains value 1, true, True or TRUE, CTL2 boolean will hold true. If java String contains value 0, false, False or FALSE, CTL2 boolean will hold false. If any other value is present in the java String, conversion fails.

Java String to CTL2 byte or cbyte

Java String to byte or cbyte conversion has empty string as result.

Java array to CTL2

Conversion of java bean array to integer, long, number (double) and decimal has zero as result.

The result of conversion from java array CTL2 boolean is false.

Java array converted to byte and cbyte is null.

Java Collection to CTL2

Conversion from java Collection to integer, long, double, decimal, string returns first item of collection.

Collection to byte and cbyte conversion has empty string as a result.

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