Develop Reference

Firestore - Use update method for document but with Object (Java)

I want to update a document with a User object that I have, but I do not want the document to be created if it does not exist, and therefore I cannot use "DocumentReference.set" with "SetOptions.Merge()" (to my understanding).
However, according to this post (Difference between set with {merge: true} and update), "update" is actually the command I need. My problem is, it doesn't seem like update accepts a Java object.
I do not want to check whether or not the document exists myself, as this will result in an unnecessary read.
Is there any way around this?
Here is my code (I have removed success and failure listeners for simplicity):
public void saveUser(User user)
{
CollectionReference collection = db.collection("users");
String id = user.getId();
if (id.equals(""))
{
collection.add(user);
}
else
{
// I need to ensure that the ID variable for my user corresponds
// with an existing ID, as I do not want a new ID to be generated by
// my Java code (all IDs should be generated by Firestore auto-ID)
collection.document(ID).set(user);
}
}

It sounds like you:
Want to update an existing document
Are unsure if it already exists
Are unwilling to read the document to see if it exists
If this is the case, simply call update() and let it fail if the document doesn't exist. It won't crash your app. Simply attach an error listener to the task it returns, and decide what you want to do if it fails.
However you will need to construct a Map of fields and values to update using the source object you have. There are no workarounds for that.

XWiki extension : detect event space creation

Based on the documentation here we can see that in a xwiki java extension, we can intercept the event UserCreation like that :
https://extensions.xwiki.org/xwiki/bin/view/Extension/Observation%20Module%20Local#HWritinganEventListenerinVelocityinaWikipage
public void onEvent(Event event, Object source, Object data)
{
XWikiDocument document = (XWikiDocument) source;
String wikiName = document.getDocumentReference().getWikiReference().getName();
DocumentReference userClass = new DocumentReference(wikiName, "XWiki", "XWikiUsers");
if (document.getXObject(userClass) != null) {
}
I want the same thing, but I want to detect the event space creation ( so basically when you add a space( basically a space is the main root page of an article ) in your wiki. But I didn't found any class like XWikiUsers for the space or the page.
It don't want to do it with velocity or groovy but in pure java extension and I have no clue, the doc is very huge but it's hard to found what I' looking for.

Technically, a "space" gets created whenever a page is created under it (either terminal page or WebHome).
So you could either:
do a query each time a page is being created (DocumentCreatingEvent, so not yet DocumentCreatedEvent) and then do a query (see https://extensions.xwiki.org/xwiki/bin/view/Extension/Query%20Module) to see if the space (matching the new document's space reference) matches an existing one or a deeper nested one inside the database... or
check if the newly created document (DocumentCreatedEvent) has the name WebHome which would be much better in terms of performance, but it will not work if you are working with terminal documents (i.e. other documents than 'WebHome' ones, see https://www.xwiki.org/xwiki/bin/view/Documentation/UserGuide/Features/ContentOrganization/#HTerminology

Firebase Firestore get only one field from document [duplicate]

Here is my data structure:
I have an ios app that is attempting to access data from Cloud Firestore. I have been successful in retrieving full documents and querying for documents. However I need to access specific fields from specific documents. How would I make a call that retrieves me just the value of one field from Firestore in swift? Any Help would be appreciated.

There is no API that fetches just a single field from a document with any of the web or mobile client SDKs. Entire documents are always fetched when you use getDocument(). This implies that there is also no way to use security rules to protect a single field in a document differently than the others.
If you are trying to minimize the amount of data that comes across the wire, you can put that lone field in its own document in a subcollection of the main doc, and you can request that one document individually.
See also this thread of discussion.
It is possible with server SDKs using methods like select(), but you would obviously need to be writing code on a backend and calling that from your client app.

This is actually quite simple and very much achievable using the built in firebase api.
let docRef = db.collection("users").document(name)
docRef.getDocument(source: .cache) { (document, error) in
if let document = document {
let property = document.get(field)
} else {
print("Document does not exist in cache")
}
}

There is actually a way, use this sample code provided by Firebase itself
let docRef = db.collection("cities").document("SF")
docRef.getDocument { (document, error) in
if let document = document, document.exists {
let property = document.get('fieldname')
print("Document data: \(dataDescription)")
} else {
print("Document does not exist")
}
}

I guess I'm late but after some extensive research, there is a way in which we can fetch specific fields from firestore. We can use the select keyword, your query would be somthing like (I'm using a collection for a generalized approach):
const result = await firebase.database().collection('Users').select('name').get();
Where we can access the result.docs to further retrieved the returned filtered result. Thanks!

//this is code for javascript
var docRef = db.collection("users").doc("ID");
docRef.get().then(function(doc) {
if (doc.exists) {
//gives full object of user
console.log("Document data:", doc.data());
//gives specific field
var name=doc.get('name');
console.log(name);
} else {
// doc.data() will be undefined in this case
console.log("No such document!");
}
}).catch(function(error) {
console.log("Error getting document:", error);
});

Query regarding Adobe AEM

How can I access the history of a Workflow instance using the Adobe AEM api for java?
Say I've created one workflow which contains 3 workitems. I want to access the details associated with all the workitems for that workflow (E.g.Status,Title,User,StartTime,EndTime,Action,Comment).

Take a look at the following classes.
com.day.cq.workflow.WorkflowSession
https://docs.adobe.com/docs/en/cq/5-6-1/javadoc/com/day/cq/workflow/WorkflowService.html
and
com.day.cq.workflow.WorkflowSession
https://docs.adobe.com/docs/en/cq/5-6-1/javadoc/com/day/cq/workflow/WorkflowSession.html
If you want to see a code example on how to filter on a particular workflow instance, you can find a lot of documents in the following file of your AEM instance:
/crx/de/index.jsp#/libs/cq/workflow/components/console/archive/json.jsp
In summary, you will need to create a workflow service and fetch the model to iterate over it's instances to apply relevant filters.
Alternatively, you can write a query to get data from /var/eventing/jobs node which is essentially a workflow instance data store.

This might work for you
List<HistoryItem> history = workflowSession.getHistory(workItem.getWorkflow());
HistoryItem current;
if (history.size() > 0) {
HistoryItem current = history.get(history.size() - 1);
do {
current = current.getPreviousHistoryItem();
} while (current != null);
}

How to set the content of a RichTextItem field in a Notes document?

This one seems like it should be simple enough. I'm writing a Notes Agent in Java; it calculates a fairly large amount of numeric data (a 6400-entry array of doubles) that I want to store in an existing document, updating a field. Because of Notes' field limitations, I figured I needed to use a RichText field to do that. (My initial attempt to write to a multi-value Number field resulted in it failing to save somewhere between an array of size 4000 and 5000.) It's not clear to me how one stores that value in a RichTextItem, though. All my attempts have failed. In one case, using doc.replaceItemValue(), it seemed to convert the item to a Text List. Getting the item, casting it to a RichTextItem, and calling setValues() or setValueString() doesn't seem to do anything. This shouldn't be this hard! Any pointers?
(Alternately: Any better suggestion for how to store my array in a document in the database?)
Thanks,
Reid

You'll need to create a RichTextItem and use the methods on that object to populate it:
import lotus.domino.*;
import java.util.Vector;
public class JavaAgent extends AgentBase {
public void NotesMain() {
try {
Session session = getSession();
AgentContext agentContext =
session.getAgentContext();
// (Your code goes here)
Database db = agentContext.getCurrentDatabase();
Document doc = db.createDocument();
Item subject = doc.replaceItemValue("Subject",
"Project description");
RichTextItem body = doc.createRichTextItem("Body");
body.appendText("Cartoon book for children
ages 9-12");
// Print text of subject and body
System.out.println(subject.getText());
System.out.println(body.getText());
// Save the document
doc.save(true, true);
} catch(Exception e) {
e.printStackTrace();
}
}
}
UPDATE:
If you need to edit an existing document, instead of creating a new rich text item, you would get the existing one.
RichTextItem body = doc.GetFirstItem("Body"); // instead of createRichTextItem

You can bypass the Notes' field limitations. You can flag your item as «contains non-summary data» by using the NotesItem.IsSummary property. You need to set this property to false. But remember, you cannot use this item in views and folders.
Here is example:
Vector vector = new Vector();
for (int index = 0; index<6400;index++)
vector.addElement(new Double(Math.random()*100));
Item item = document.replaceItemValue("YourFieldName", vector);
item.setSummary(false);
document.save(true,true);

As for the question of "better" solution. I've recently written some code where I serialize/deserialize Java objects as JSON strings. This way they are well readable and easily restorable. I guess for the plain array it's a little problem. Especially if you do not want to restore it and have not interest to look at it (well, but probably it should be one or other :-)
And yes, you have to store it in the rich text anyway. Alternative you might write a text document and attach it in the RT field (again RT :-). Pretty usual scenario and easy to do.
Finally you could store data as database objects, but I guess from Java you do not really have access to do it. And it does not seem to be in any way better.