I know that generally, we need to do something similar to this for getting a document back from mongodb in spring data:
Define a class and annotate it with #Document:
#Document ("persons")
public class Person
Use MongoTemplete:
mongoOps.findById(p.getId(), Person.class);
The problem is that in runtime I don't know the class type of the document, I just have its string collection name and its string Id. How is it possible to retrieve the document using SpringData? Something like this:
db.myCollectionName.findOne({_id: myId})
The result object type is not a concern, it can be even an object, I just want to map it to a jackson JsonNode.
A possible workaround for this you can use the aggregate function of mongooperation like this
AggregationResults<Object> aggResults = mongoOps.aggregate(newAggregation(match(Criteria.where("_id").is(myId)) ,
myCollectionName, Object.class);
return aggResults.getUniqueMappedResult();
Related
I have recently started to use Spring Data MongoDB and I wonder if there is any way to avoid writing entities' attributes explicitly as they are stored in the database. For example, given the following class representing a MongoDB collection:
public class Employee {
#Id
public String id;
private double salary;
...
}
If I want to make a query using MongoTemplate like:
public List findEmployeeBySalaryRange(double salary) {
Query query = new Query();
query.addCriteria(Criteria.where("salary").lt(salary));
...
}
I would like to avoid writing "salary", since that will make the code harder to maintain in the future in case the field name changes. I am thinking of something like getting the field name from the class attribute, but I am not quite sure how. Is there a way to do it? I have looked into the documentation but did not find anything related unless I missed it.
Thanks in advance.
You may create a Utility Class to store all database field names, use #Field annotation on field with constant from that class and use that constant in query to avoid error prone hardcoded Strings.
In Employee Model
#Field(DbFields.SALARY)
private double salary;
In Query,
query.addCriteria(Criteria.where(DbFields.SALARY).lt(salary));
In DbFields Utility class
public static final String SALARY = "salary";
I am new to Salesforce and want to code one requirement, I have an api name in string variable through which I want to create an object of that class.
For Eg. Object name is Account which is stored in string variable.
String var = 'Account'
Now I want to create object of 'Account'. In java it is possible by Class.forName('Account') but similar approach is not working in Salesforce Apex.
Can anyone please help me out in this.
Have a look at Type class. The documentation for it isn't terribly intuitive, perhaps you'll benefit more from the article that introduced it: https://developer.salesforce.com/blogs/developer-relations/2012/05/dynamic-apex-class-instantiation-in-summer-12.html
I'm using this in managed package code which inserts Chatter posts (feed items) only if the org has Chatter enabled:
sObject fItem = (sObject)System.Type.forName('FeedItem').newInstance();
fItem.put('ParentId', UserInfo.getUserId());
fItem.put('Body', 'Bla bla bla');
insert fItem;
(If I'd hardcode the FeedItem class & insert it directly it'd mark my package as "requires Chatter to run").
Alternative would be to build a JSON representation of your object (String with not only the type but also some field values). You could have a look at https://salesforce.stackexchange.com/questions/171926/how-to-deserialize-json-to-sobject
At the very least now you know what keywords & examples to search for :)
Edit:
Based on your code snippet - try something like this:
String typeName = 'List<Account>';
String content = '[{"attributes":{"type":"Account"},"Name":"Some account"},{"attributes":{"type":"Account"},"Name":"Another account"}]';
Type t = Type.forName(typeName);
List<sObject> parsed = (List<sObject>) JSON.deserialize(content, t);
System.debug(parsed);
System.debug(parsed[1].get('Name'));
// And if you need to write code "if it's accounts then do something special with them":
if(t == List<Account>.class){
List<Account> accs = (List<Account>) parsed;
accs[1].BillingCountry = 'USA';
}
I am using Objectify to manage GAE Datastore for my GWT app. The problem is that I am not using queries properly and I get UmbrellaExceptions as per below:
Caused by: java.lang.RuntimeException: Server Error: java.lang.String cannot be cast to java.lang.Number
at com.google.web.bindery.requestfactory.shared.Receiver.onFailure(Receiver.java:44)
Say that I have a class Box with a unique field String id. I want to get the Box object whose id == "cHVQP6zZiUjM"
This is how I do it now:
public Box getBox(String boxId)
{
Objectify ofy = ObjectifyService.begin();
Query<Box> q=ofy.query(Box.class).filter("id",boxId);
Box targetBox = q.get();
return targetBox;
}
#Entity
public class Box extends DatastoreObject{
private String id;
private String title;
}
I tried doing this with ofy.load() but that method is not defined in my class Objectify (I don't know why).
Your key is encoded. Try using:
Box targetBox = ofy.get(Box.class, KeyFactory.stringToKey(boxId));
To decode your key.
The short answer: You are missing the #Id annotation in your entity.
The long answer: Id fields are special in the datastore. The id is not a real property, but rather a part of the Key that identifies the entity. You can't really filter on id fields, but you can filter on a special field called __key__. Objectify is somewhat clever about letting you filter by the id field and converting this to a __key__ filter under the covers, but it can't do it if you don't annotate the entity properly!
Actually I'm a little confused because Objectify shouldn't let you register the entity without an #Id field.
By the way, there are two sections of the documentation: Objectify4 (release coming soon) and Objectify3. Since you're using Ofy3, there is no load() method.
Another thing: Get-by-key operations are strongly preferred to queries when the operations are equivalent (as they are in your example).
I have a requirement to design a RESTful Service using RESTEasy. Clients can call this common service with any number of Query Parameters they would want to. My REST code should be able to read these Query Params in some way. For example if I have a book search service, clients can make the following calls.
http://domain.com/context/rest/books/searchBook?bookName=someBookName
http://domain.com/context/rest/books/searchBook?authorName=someAuthor& pubName=somePublisher
http://domain.com/context/rest/books/searchBook?isbn=213243
http://domain.com/context/rest/books/searchBook?authorName=someAuthor
I have to write a service class like below to handle this.
#Path("/books")
public class BookRestService{
// this is what I currently have, I want to change this method to in-take all the
// dynamic parameters that can come
#GET
#Path("/searchBook")
public Response searchBook(#QueryParam("bookName") String bookName,#QueryParam("isbn") String isbn) {
// fetch all such params
// create a search array and pass to backend
}
#POST
#Path("/addBook")
public Response addBook(......) {
//....
}
}
Sorry for the bad format (I couldn't get how code formatting works in this editor!). As you can see, I need to change the method searchBook() so that it will take any number of query parameters.
I saw a similar post here, but couldn't find the right solution.
How to design a RESTful URL for search with optional parameters?
Could any one throw some light on this please?
The best thing to do in this case would be using a DTO containing all the fields of your search criteria. For example, you mentioned 4 distinct parameters.
Book Name (bookName)
Author Name (authorName)
Publisher Name (pubName)
ISBN (isbn)
Create a DTO containing the fields having the following annotations for every property you want to map the parameters to:
public class CriteriaDTO{
#QueryParam("isbn")
private String isbn;
.
.
Other getter and setters of other properties
}
Here is a method doing that for your reference:
#GET
#Produces("application/json")
#Path("/searchBooks")
public ResultDTO search(#Form CriteriaDTO dto){
}
using following URL will populate the CriteriaDTO's property isbn automatically:
your.server.ip:port/URL/Mapping/searchBooks?isbn=123456789&pubName=testing
A similar question was asked here: How do you map multiple query parameters to the fields of a bean on Jersey GET request?
I went with kensen john's answer (UriInfo) instead. It allowed to just iterate through a set to check which parameters were passed.
In the python app engine docs, I see something called dbReferenceProperty. I can't understand what it is, or how it's used. I'm using the java interface to app engine, so I'm not sure if there's an equivalent.
I'm interested in it because it sounds like some sort of pseudo-join, where we can point a property of a class to some other object's value - something like if we had:
class User {
private String mPhotoUrl;
private String mPhone;
private String mState;
private String mCountry;
.. etc ..
}
class UserLite {
#ReferenceProperty User.mPhotoUrl;
private String mPhotoUrl;
}
then if we had to update a User object's mPhotoUrl value, the change would somehow propagate out to all UserLite instances referencing it, rather than having to update every UserLite object instance manually,
Thanks
A db.ReferenceProperty simply holds the key of another datastore entity, which is automatically fetched from the datastore when the property is used.
There's some additional magic where the entity that is referenced has access to a query for entities of type Foo that reference it in the special attribute foo_set.
The Java datastore API instead has owned relationships, which serve the same purpose.