com.bazaarvoice.jolt

Class Chainr

java.lang.Object

com.bazaarvoice.jolt.Chainr

All Implemented Interfaces:

ContextualTransform, JoltTransform, Transform

public class Chainr
extends Object
implements Transform, ContextualTransform

Chainr is the JOLT mechanism for chaining JoltTransforms together. Any of the built-in JOLT transform types can be called directly from Chainr. Any custom-written Java transforms can be adapted in by implementing the Transform or SpecDriven interfaces. A Chainr spec should be an array of objects in order that look like this: [ { "operation": "[operation-name]", // stuff that the specific transform needs go here }, ... ] Each operation is called in the order that it is specified within the array. The original input to Chainr is passed into the first operation, with its output passed into the next, and so on. The output of the final operation is returned from Chainr. Currently, [operation-name] can be any of the following: - shift: (Shiftr) a tool for moving parts of an input JSON document to a new output document - default: (Defaultr) a tool for applying default values to the provided JSON document - remove: (Removr) a tool for removing specific values from the provided JSON document - sort: (Sortr) sort the JSON document - java: passes control to whatever Java class you specify as long as it implements the Transform interface Shift, default, and remove operation all require a "spec", while sort does not. [ { "operation": "shift", "spec" : { // shiftr spec } }, { "operation": "sort" // sort does not need a spec }, ... ] Custom Java classes that implement Transform and/or SpecDriven can be loaded by specifying the full className to load. Additionally, if upon reflection of the class we see that it is an instance of a SpecDriven, then we will construct it with a the supplied "spec" object. [ { "operation": "com.bazaarvoice.tuna.CustomTransform", "spec" : { ... } // optional spec to use to construct a custom Transform if it has the SpecDriven marker interface. }, ... ]

Constructor Summary

Constructors

Constructor and Description
Chainr(List<JoltTransform> joltTransforms)

Method Summary

Methods

Modifier and Type	Method and Description
static Chainr	fromSpec(Object input)
static Chainr	fromSpec(Object input, ChainrInstantiator instantiator)
List<ContextualTransform>	getContextualTransforms() This method allows Chainr clients to examine the ContextualTransforms in this Chainr instance.
boolean	hasContextualTransforms()
Object	transform(int from, int to, Object input) Useful for testing and debugging.
Object	transform(int from, int to, Object input, Map<String,Object> context) Have Chainr run a subset of the transforms in it's spec.
Object	transform(int to, Object input) Have Chainr run a subset of the transforms in it's spec.
Object	transform(int to, Object input, Map<String,Object> context) Useful for testing and debugging.
Object	transform(Object input) Execute a transform on some input JSON with optionally provided "context" and return the result.
Object	transform(Object input, Map<String,Object> context) Runs a series of Transforms on the input, piping the inputs and outputs of the Transforms together.

Methods inherited from class java.lang.Object

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

Constructor Detail

Chainr

public Chainr(List<JoltTransform> joltTransforms)

Method Detail

fromSpec

public static Chainr fromSpec(Object input)

fromSpec

public static Chainr fromSpec(Object input,
              ChainrInstantiator instantiator)

transform

public Object transform(Object input,
               Map<String,Object> context)

Runs a series of Transforms on the input, piping the inputs and outputs of the Transforms together. Chainr instances are meant to be immutable once they are created so that they can be used many times. The notion of passing "context" to the transforms allows chainr instances to be reused, even in situations were you need to slightly vary.

Specified by:

transform in interface ContextualTransform

Parameters:

input - a JSON (Jackson-parsed) maps-of-maps object to transform

context - optional tweaks that the consumer of the transform would like

Returns:

an object representing the JSON resulting from the transform

Throws:

TransformException - if the specification is malformed, an operation is not found, or if one of the specified transforms throws an exception.

transform

public Object transform(Object input)

Description copied from interface: Transform

Execute a transform on some input JSON with optionally provided "context" and return the result.

Specified by:

transform in interface Transform

Parameters:

input - the JSON object to transform in plain vanilla Jackson Map style

Returns:

the results of the transformation

transform

public Object transform(int to,
               Object input)

Have Chainr run a subset of the transforms in it's spec. Useful for testing and debugging.

Parameters:

input - the input data to transform

to - transform from the chainrSpec to end with: 0 based index exclusive

transform

public Object transform(int to,
               Object input,
               Map<String,Object> context)

Useful for testing and debugging.

Parameters:

input - the input data to transform

to - transform from the chainrSpec to end with: 0 based index exclusive

context - optional tweaks that the consumer of the transform would like

transform

public Object transform(int from,
               int to,
               Object input)

Useful for testing and debugging.

Parameters:

input - the input data to transform

from - transform from the chainrSpec to start with: 0 based index

to - transform from the chainrSpec to end with: 0 based index exclusive

transform

public Object transform(int from,
               int to,
               Object input,
               Map<String,Object> context)

Have Chainr run a subset of the transforms in it's spec. Useful for testing and debugging.

Parameters:

input - the input data to transform

from - transform from the chainrSpec to start with: 0 based index

to - transform from the chainrSpec to end with: 0 based index exclusive

context - optional tweaks that the consumer of the transform would like

hasContextualTransforms

public boolean hasContextualTransforms()

Returns:

true if this Chainr instance has any ContextualTransforms

getContextualTransforms

public List<ContextualTransform> getContextualTransforms()

This method allows Chainr clients to examine the ContextualTransforms in this Chainr instance. This may be helpful when building the "context".

Returns:

List of ContextualTransforms used by this Chainr instance