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package org.openmrs.module.fhir.api.merge;
/**
* <h1>MergeBehaviour</h1>
* Reflects merging behaviour for type T.
* <p><b>Note:</b> use Object.class as a type T for more generic merging behaviour.</p>
*
* @see <a href="https://issues.openmrs.org/browse/SYNCT-243">SYNCT-243</a>
* @since 1.15.0
*/
public interface MergeBehaviour<T> {
/**
* <p>Resolves merge conflicts for entities' synchronization.</p>
*
* @param local represents local version of an entity
* @param foreign represents foreign version of an entity
* @param clazz represents specific class which extends T
* @return returns a result which depends on implemented merging behaviour
*/
MergeResult<T> resolveDiff(Class<? extends T> clazz, T local, T foreign);
} |
MergeResult is an abstract object and it is extended by either MergeSuccess or MergeConflict. The MergeConflict represents a situation when MergeBehaviour couldn't merge objects automatically. The MergeSuccess represents situations when:
- local object overrides another,
- foreign object overrides another,
- local and foreign objects are merged,
- we do not have to change any objects.
An example implementation might look like this:
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package org.openmrs.module.fhir.api.merge; import org.openmrs.BaseOpenmrsData; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.net.URI; public class TestMergeBehaviour implements MergeBehaviour<BaseOpenmrsData> { @Override public MergeResult<BaseOpenmrsData> resolveDiff(Class<? extends BaseOpenmrsData> clazz, BaseOpenmrsData local, BaseOpenmrsData foreign) { MergeResult<BaseOpenmrsData> result; BaseOpenmrsData merged; if (local.getDateChanged().after(foreign.getDateChanged())) { merged = deepClone(foreign); result = new MergeSuccess<>(clazz, local, foreign, URI.create("www.example.com/api/object"), merged, true, false); } else { result = new MergeConflict<>(clazz, local, foreign); } return result; } private BaseOpenmrsData deepClone(BaseOpenmrsData org) { BaseOpenmrsData clone = null; try { ByteArrayOutputStream baOUT = new ByteArrayOutputStream(); ObjectOutputStream oOUT = new ObjectOutputStream(baOUT); oOUT.writeObject(org); ByteArrayInputStream baIN = new ByteArrayInputStream(baOUT.toByteArray()); ObjectInputStream oIN = new ObjectInputStream(baIN); clone = (BaseOpenmrsData) oIN.readObject(); } catch (IOException | ClassNotFoundException e) { e.printStackTrace(); } return clone; } } |
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