com.pushtechnology.diffusion.datatype.json

Interface JSONDelta

public interface JSONDelta

Structural delta type for JSON.

A JSONDelta describes the differences between two JSON values. Unlike a binary delta, a structural delta can be queried to determine its effect. The removed() and inserted() methods provide full details of the differences between the two values.

An instance can be created from two JSON values using JSON.diff(JSON).

JSONDeltas are useful for identifying small changes to complex JSON values. Here's any example of how to use this class to filter interesting changes in a ValueStream.

 public class ExampleStream implements ValueStream<JSON> {
   public void onValue(String topicPath, JSON oldValue, JSON newValue) {
     JSONDelta delta = newValue.diff(oldValue);

     if (!delta.removed().intersection("/address").isEmpty() ||
         !delta.inserted().intersection("/address").isEmpty()) {

         // The "address" field has changed.
         processAddress(newValue);
     }
   }

   // ...
 }
 

Since:

5.7

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	JSONDelta.ChangeMap An unmodifiable map describing the changes to a JSON value.

Method Summary

Modifier and Type	Method and Description
boolean	hasChanges() Returns whether the two JSON values used to create this instance are different.
JSONDelta.ChangeMap	inserted() Returns the parts of the second JSON value not found in the first JSON value.
JSONDelta.ChangeMap	removed() Returns the parts of the first JSON value not found in the second JSON value.

Method Detail

removed

JSONDelta.ChangeMap removed()

Returns the parts of the first JSON value not found in the second JSON value.

Returns:

the removed parts. The JSON Pointer references used for the keys are relative to first JSON value.

inserted

JSONDelta.ChangeMap inserted()

Returns the parts of the second JSON value not found in the first JSON value.

Returns:

the removed parts. The JSON Pointer references used for the keys are relative to second JSON value.

hasChanges

boolean hasChanges()

Returns whether the two JSON values used to create this instance are different. It is equivalent to {!@code inserted().isEmpty() || !removed().isEmpty()}.

Returns:

true if this delta has an effect