Denormalizer

Short Description
Ports
Metadata
Denormalizer Attributes
Details
CTL Interface
Java Interface
Examples
Best Practices
See also

Short Description

Denormalizer creates a single output record from one or more input records. Input records should be sorted.

ComponentSame input metadataSorted inputsInputsOutputsJavaCTLAuto-propagated metadata
Denormalizer-
no
11
yes
yes
no

Ports

Port typeNumberRequiredDescriptionMetadata
Input0
yes
For input data records.any
Output0
yes
For denormalized data records.any

Metadata

Denormalizer does not propagate metadata.

Denormalizer does not have metadata templates.

Denormalizer does not require any specific metadata fields.

Denormalizer Attributes

AttributeReqDescriptionPossible values
Basic
Key[1]

A key that creates groups of input data records according to its value. Adjacent input records with the same value of Key are considered to be members of one group. One output record is composed from members of such group. For more information, see Key.

 
Group size[1]

A group may be defined by exact number of its members. E.g. each five records form a single group. The input record count must be a multiple of group size (see Allow incomplete last group). This is mutually exclusive with the key attribute.

a number
Denormalize[2]Definition of how to denormalize records, written in the graph in CTL or Java. 
Denormalize URL[2]

The name of an external file, including the path, containing the definition of how to denormalize records, written in CTL or Java.

 
Denormalize class[2]The name of an external class defining how records should be normalized. 
Equal NULL 

By default, records with null values of key fields are considered to be equal. If false, they are considered to be different.

true (default) | false
Denormalize source charset 

Encoding of the external file defining the transformation.

The default encoding depends on DEFAULT_SOURCE_CODE_CHARSET in defaultProperties.

E.g. UTF-8
Advanced
Allow incomplete last group 

In case input records grouping is specified by the Group size attribute, the number of input records must be a multiple of group size. Using this attribute, this condition can be suppressed. The last group does not need to be complete.

true | false (default)
Deprecated
Sort order 

Order in which groups of input records are expected to be sorted. See Sort order

Auto (default) | Ascending | Descending | Ignore
Error actions 

The definition of an action that should be performed when the specified transformation returns some Error code. See Return Values of Transformations.

 
Error log 

A URL of the file to which error messages for specified Error actions should be written. If not set, they are written to Console.

 

[1] group size has higher priority than key. If neither of these attributes is specified, all records will form a single group.

[2] One of them must specified.

Details

Denormalizer receives sorted data through a single input port, checks Key values and creates one output record from one or more adjacent input records with the same Key value.

Denormalizer requires transformation. The transformation can be defined in CTL (see CTL Interface) or in Java (see Java Interface) or using existing .class file (Denormalize class attribute).

To define transformation, use one of the three transformation attributes: Denormalize, Denormalize URL or Denormalize class.

Diagram below describes flow of function calls in Denormalizer.

Denormalizer code workflow

Figure 57.1. Denormalizer code workflow


The function append() is called once for each input record. The function transform() is called once for each group of input records.

If you do not define any of the optional functions init(), preExecute(), clean() or postExecute(), the execution flow continues with the next function according to the diagram.

If you do not specify the appendOnError() or transformOnError() functions and an error occurs, the execution of graph fails.

The transformation uses a CTL template for Denormalizer, implements a RecordDenormalize interface or inherits from a DataRecordDenormalize superclass. The interface methods are listed in CTL Interface and Java Interface.

Key

Key is expressed as a sequence of field names separated from each other by a semicolon, colon, or pipe.

Example 57.2. Key for Denormalizer

first_name;last_name


In this Key, first_name and last_name are fields of metadata on input port.

Sort order

If the records are denormalized by the Key, i.e. not by the Group size, the input records must be grouped according to the Key field value. Then, depending on the sorting order of the groups, select the proper Sort order:

  • Auto - the sorting order of the groups of input records is guessed from the first two records with different value in the key field, i.e. from the first records of the first two groups.

  • Ascending - if the groups of input records with the same key field value(s) are sorted in ascending order.

  • Descending - if the groups of input records with the same key field value(s) are sorted in descending order.

  • Ignore - if the groups of input records with the same key field value(s) are not sorted.

CTL Interface

CTL Templates
Access to input and output fields

The transformation written in CTL uses a CTL template for Denormalizer. Only the functions count() and transform() are mandatory.

Once you have written your transformation, you can also convert it to Java language code by clicking the corresponding button at the upper right corner of the tab.

You can open the transformation definition as another tab of the graph (in addition to the Graph and Source tabs of Graph Editor) by clicking the corresponding button at the upper right corner of the tab.

CTL Templates

Table 57.3. Functions in Denormalizer

CTL Template Functions
boolean init()
RequiredNo
DescriptionInitializes the component, sets up the environment and global variables.
InvocationCalled before processing the first record
Returnstrue | false (in case of false graph fails)
integer append()
Requiredyes
Input Parametersnone
Returns

Integer numbers. Negative value lower than -1 aborts processing. Any non-negative value means a successful pass.

InvocationCalled repeatedly, once for each input record
Description

For the group of adjacent input records with the same Key values, it appends the information from which the resulting output record is composed.

If append() fails and the user has not defined any appendOnError(), the whole graph will fail.

If any of the input records causes fail of the append() function, and if the user has defined appendOnError() function, processing continues in this appendOnError() at the place where append() failed. The append() passes to the appendOnError() error message and stack trace as arguments.

Example
function integer append() {
    CustomersInGroup++;
    myLength = length(errorCustomers);	
    if(!isInteger($in.0.OneCustomer)) {
        errorCustomers = errorCustomers + iif(myLength > 0 ," - ","") + $in.0.OneCustomer;
    }
    customers = customers + iif(length(customers) > 0 ," - ","") + $in.0.OneCustomer;
    groupNo = $in.0.GroupNo;
    return OK;
}
integer transform()
Requiredyes
Input Parametersnone
ReturnsInteger numbers. For detailed information, see Return Values of Transformations.
InvocationCalled repeatedly, once for each output record.
Description

It creates output records.

If transform() fails and the user has not defined any transformOnError(), the whole graph will fail.

If any part of the transform() function for some output record causes fail of the transform() function, and if the user has defined the transformOnError() function, processing continues in the transformOnError() at the place where transform() failed.

The transformOnError() function gets the information gathered by transform() that was get from previously successfully processed code. Also error message and stack trace are passed to transformOnError().

Example
function integer transform() {
    $out.0.CustomersInGroup = CustomersInGroup;
    $out.0.CustomersOnError = errorCustomers;	
    $out.0.Customers = customers;
    $out.0.GroupNo = groupNo;
    return OK;
}
void clean()
Requiredno
Input Parametersnone
Returnsvoid
Invocation

Called repeatedly, once for each output record.

The clean() function is called after the transform() function.

DescriptionReturns the component to the initial settings.
Example
function void clean(){
    customers = "";
    errorCustomers = "";
    groupNo = 0;
    CustomersInGroup = 0;
}
integer appendOnError(string errorMessage, string stackTrace)
Requiredno
Input Parametersstring errorMessage
string stackTrace
Returns

Integer numbers. Positive integer numbers are ignored, meaning of 0 and negative values is described in Return Values of Transformations

InvocationCalled if append() throws an exception.
Description

The function handles errors which occurred in the append() function.

If any of the input records causes fail of the append() function, and if the user has defined the appendOnError() function, processing continues in this appendOnError() at the place where append() failed.

The appendOnError() function gets the information gathered by append() that was get from previously successfully processed input records. The error message and stack trace are passed to appendOnError(), as well.

Example
function integer appendOnError(
                  string errorMessage, 
                  string stackTrace) {
    printErr(errorMessage);
    return CustomersInGroup;
}
integer transformOnError(Exception exception, stackTrace)
Requiredno
Input Parametersstring errorMessage
string stackTrace
ReturnsInteger numbers. For detailed information, see Return Values of Transformations.
InvocationCalled if transform() throws an exception.
Description

The function handles errors which occurred in transform() function.

If any part of the transform() function fails, and if the user has defined the transformOnError() function, processing continues in the transformOnError() at the place where transform() failed.

The transformOnError() function gets the information gathered by transform() that was get from previously successfully processed code. The error message and stack trace are passed to transformOnError(), as well.

The function transformOnError() creates output records.

Example
function integer transformOnError(
                  string errorMessage, 
                  string stackTrace) {
    $out.0.CustomersInGroup = CustomersInGroup;
    $out.0.ErrorFieldForTransform = errorCustomers;	
    $out.0.CustomersOnError = errorCustomers;
    $out.0.Customers = customers;
    $out.0.GroupNo = groupNo;
    return OK;
}
string getMessage()
RequiredNo
DescriptionPrints the error message specified and invoked by the user.
Invocation

Called in any time specified by the user (called only when either append(), transform(), appendOnError() or transformOnError() returns value less than or equal to -2).

Returnsstring
void preExecute()
RequiredNo
Input parametersNone
Returnsvoid
Description

May be used to allocate and initialize resources required by the transform.

All resources allocated within this function should be released by the postExecute() function.

InvocationCalled during each graph run before the transform is executed.
void postExecute()
RequiredNo
Input parametersNone
Returnsvoid
DescriptionShould be used to free any resources allocated within the preExecute() function.
InvocationCalled during each graph run after the entire transform was executed.

Access to input and output fields

Input records or fields

Input records or fields are accessible within the append() and appendOnError() functions only.

Output records or fields

Output records or fields are accessible within the transform() and transformOnError() functions only.

[Warning]Warning

All of the other CTL template functions allow to access neither inputs nor outputs.

Remember that if you do not hold these rules, NPE will be thrown.

Java Interface

The transformation implements methods of the RecordDenormalize interface and inherits other common methods from the Transform interface. See Common Java Interfaces. See Public CloverDX API.

Following are the methods of the RecordDenormalize interface:

  • boolean init(Properties parameters, DataRecordMetadata sourceMetadata, DataRecordMetadata targetMetadata)

    Initializes denormalize class/function. This method is called only once at the beginning of denormalization process. Any object allocation/initialization should happen here.

  • int append(DataRecord inRecord)

    Passes one input record to the composing class.

  • int appendOnError(Exception exception, DataRecord inRecord)

    Passes one input record to the composing class. Called only if append(DataRecord) throws an exception.

  • int transform(DataRecord outRecord)

    Retrieves composed output record. For detailed information about return values and their meaning, see Return Values of Transformations. In Denormalizer, only ALL, 0, SKIP, and Error codes have some meaning.

  • int transformOnError(Exception exception, DataRecord outRecord)

    Retrieves composed output record. Called only if transform(DataRecord) throws an exception.

  • void clean()

    Finalizes current round/clean after current round. Called after the transform method was called for the input record.

Examples

Converting multiple having same key records to one
Converting fixed number of records to one records

Converting multiple having same key records to one

Input records acquired from relational database contain fields companyName and product.

Denormalizer Limited |chocolate
Denormalizer Limited |coffee
Denormalizer Limited |pizza
ZXCV International   |coffee

Convert the records to following form: companyName is followed by list of products separated by commas.

Solution

Use the Key and Normalize attributes.

AttributeValue
KeycompanyName
NormalizeSee the code below
//#CTL2

string[] products;
string companyName;

function integer append() {
    append(products, $in.0.product);
    companyName = $in.0.companyName;
    return OK;
}

function integer transform() {
    $out.0.companyName = companyName;
    $out.0.products = join(",", products);
    return OK;
}

function void clean() {
    clear(products);
}

Denormalizer returns following records:

Denormalizer Limited |chocolate,coffee,pizza
ZXCV International   |coffee
[Important]Important

Records with the same Key have to be available in input data all at once. Otherwise you will get a new output record for each several subsequent records having the same key.

The best solution is to have input records sorted by Key.

Converting fixed number of records to one records

Given a list of students.

Charlie
Daniel
Agatha
Henry
Oscar
Kate
Romeo
Jane

Convert the list to groups of 3. Each group (one output record) has a number and names of its members. The names are separated by comma.

Each output record contains groupNumber and members.

Solution

Use the Group size and Normalize attributes. To be able to process the number of record not being divisible by 3, you need the Allow incomplete last group attribute.

AttributeValue
Group size3
NormalizeSee the code below
Allow incomplete last grouptrue
//#CTL2

integer groupNumber;
string[] names;

function integer append() {
    append(names, $in.0.name);
    return OK;
}

function integer transform() {
    $out.0.groupNo = groupNumber;
    $out.0.members = join(",", names);
    groupNumber++;

    return OK;
}

function boolean init() {
    groupNumber = 1;
    return true;
}

function void clean() {
    clear(names);
}

Denormalizer returns following records:

1|Charlie,Daniel,Agatha
2|Henry,Oscar,Kate
3|Romeo,Jane

Best Practices

If the transformation is specified in an external file (with Denormalize URL), we recommend users to explicitly specify Denormalize source charset.

See also

Normalizer
Rollup
Common Properties of Components
Specific Attribute Types
Common Properties of Transformers
Transformers Comparison