question about value maps

[TB3dock]

As aem forums always deletes my post for no reason, Ill try putting the question into the response part. Please read the below reply for the question.

The problem is I cant find a way to combine two value maps. doing .putAll() fails (not supported), and so does constructing a new one.

[TB3dock]

In regards to a page which shows thumbnails and summary of recent played games.  The content comes from individual game info pages which have to be looked up by ID.

We need to send a page to the client to show the played games as json so it can be rendered in react.

First i search for the required game info pages using QueryBuilder.

Then, for each page found, I use QueryBuilder again to search for the required components the page.

This returns a ValueMap for the components properties.

Now I need to combine each components ValueMap into one ValueMap for the page, add a few additional ones (like the URL of the info page), so I can pass it back, and eventually convert it to JSON to the client.

I cant see a way to instantiate a new value map, in order to manually copy each item into it.

i tried pulAll but this gives a null pointer exception.

In the next reply, ill try pasting the code so far (trying to not let AEM delete this post)

[TB3dock]

Here is the current (non working) code:

		predicate.put("path", path);
		predicate.put("type", "cq:unstructured");
		predicate.put("group.1_property", "sling:resourceType");
		predicate.put("group.1_property.value", "mysite/components/gamemain");
		predicate.put("group.2_property", "sling:resourceType");
		predicate.put("group.2_property.value", "mysite/components/gameterms");
		predicate.put("group.p.or", "true");
		
		Query query = _builder.createQuery(PredicateGroup.create(predicate), session);
		
		// should only be 2 components!
		query.setStart(0);
		query.setHitsPerPage(20);
		
		SearchResult searchResult = query.getResult();
		
		ValueMap allProps = null;
		
		for(Hit hit : searchResult.getHits()) {
			ValueMap props = hit.getProperties();
			if (allProps == null) {
				allProps  = props;
			}  else {
				allProps.putAll(props);  // Fails with null pointer exception
			}
		}
 

[TB3dock]

Below is the code so far. If I try to put it in a code block AEM deletes the post.

                predicate.put("path", path);
                predicate.put("type", "cq:unstructured");
                predicate.put("group.1_property", "sling:resourceType");
                predicate.put("group.1_property.value", "mysite/components/gamemain");
                predicate.put("group.2_property", "sling:resourceType");
                predicate.put("group.2_property.value", "mysite/components/gameterms");
                predicate.put("group.p.or", "true");
                
                Query query = _builder.createQuery(PredicateGroup.create(predicate), session);
                
                // should only be 2 components!
                query.setStart(0);
                query.setHitsPerPage(20);
                
                SearchResult searchResult = query.getResult();
                
                ValueMap allProps = null;
                
                for(Hit hit : searchResult.getHits()) {
                        ValueMap props = hit.getProperties();
                        if (allProps == null) {
                                allProps  = props;
                        }  else {
                                allProps.putAll(props);  // Fails with null pointer exception
                        }
                }

[TB3dock · Accepted solution]

Seems that ValueMaps are immutable, even if you use .put() you will get run time errors.

Instead I change everywhere which used ValueMap to use HashMap<String,Object> instead, and copy each ValueMap into this. Then I can use the full power of maps.

	public void copyProps(ValueMap from, HashMap<String,Object> to) {
		// ignore jrc: and sling: object properties.
		from.forEach((key, value) ->  {
			if (!key.startsWith("jcr:") && !key.startsWith("sling:"))  {
				to.put(key, value);
			}
		});
	}

I use the above code to convert ValueMaps into HashMaps, and to also combine several page components VAlueMaps into a single HashMap so I can send the page back as json (using Gson on the resultant master hashmap).

This relies on not using the same field names on each components properties.