I am trying to use Neo4jOperations in Spring Data Neo4j 4.
Filters can be used in Neo4jOperations for retrieving data from NodeEntity.
Eg. I have a case where there are actors with "roles" in a movie. Now,Actor and Movie is a NodeEntity and roles is a RelationshipEntity. If i query a movie for a title using Filters, it does show me the relevant details.
I want to query details in the form - "Find me actors who have relationship (any relationship) in Movie 'Cloud Atlas'." I am not able to find a way to work for this using Filters.
Filters let you specify something like key-value pairs. Can I specify key value as "roles.movies.title" and query for the results?
Tried it this way, it does not work out.
Do not want to use Custom Query as we want to keep the query generic so that it can accomodate a lot of use cases. Attaching a custom query will mean that it can address only a specific case.
It is possible to implement your own FilterFunction, however, much simpler is to use a custom query for this. Example:
#Query("MATCH (a:Actor)-[]-(n:Movie {name: "Cloud Atlas"}) return n")
public List<Actor> findActorsRelatedToCloudAtlas()
Related
I am new to MongoDB. And I have the following issue on currently developing web application.
We have an application where we use mongoDB to store data.
And we have an API where we search for the document via text search.
As an example: if the user type “New York” then the request should send the all the available data in the collection to the keyword “New York". (Here we call the API for each letter typed.) We have nearly 200000 data in the DB. Once the user searches for a document then it returns nearly 4000 data for some keywords. We tried with limiting the data to 5 – so it returns the top 5 data, and not the other available data. And we tried without limiting data now it returns hundreds and thousands of data as I mentioned. And it causes the request to slow down.
At Frontend we Bind search results to a dropdown. (NextJs)
My question:
Is there an optimizing way to search a document?
Are there any suggestions of a suitable way that I can implement this requirement using mongoDB and net5.0?
Or any other Implementation methods regarding this requirement?
Following code segment shows the query to retrieve the data to the incomming keyword.
var hotels = await _hotelsCollection
.Find(Builders<HotelDocument>.Filter.Text(keyword))
.Project<HotelDocument>(hotelFields)
.ToListAsync();
var terminals = await _terminalsCollection
.Find(Builders<TerminalDocument>.Filter.Text(keyword))
.Project<TerminalDocument>(terminalFeilds)
.ToListAsync();
var destinations = await _destinationsCollection
.Find(Builders<DestinationDocument>.Filter.Text(keyword))
.Project<DestinationDocument>(destinationFields)
.ToListAsync();
So this is a classic "autocomplete" feature, there are some known best practices you should follow:
On the client side you should use a debounce feature, this is a most. there is no reason to execute a request for each letter. This is most critical for an autocomplete feature.
On the backend things can get a bit more complicated, naturally you want to be using a db that is suited for this task, specifically MongoDB have a service called Atlas search that is a lucene based text search engine.
This will get you autocomplete support out of the box, however if you don't want to make big changes to your infra here are some suggestions:
Make sure the field your searching on is indexed.
I see your executing 3 separate requests, consider using something like Task.WhenAll to execute all of them at once instead of 1 by 1, I am not sure how the client side is built but if all 3 entities are shown in the same list then ideally you merge the labels into 1 collection so you could paginate the search properly.
As mentioned in #2 you must add server side pagination, no search engine can exist without one. I can't give specifics on how you should implement it as you have 3 separate entities and this could potentially make pagination implementation harder, i'd consider wether or not you need all 3 of these in the same API route.
Although there are tons of similar questions regarding the REST API design, I am asking a very specific question that I could not found answers in other similar questions.
Suppose that I am trying to GET a list of devices in the database with Building_Type and Room_Type filters. I would like to pass an array of filters, and each filter contains two field as a composite key. I've found standard practice to pass parameter arrays, but I could not find a good way for composite keys in the array.
Example:
GET /api/v1/devices?building_type=Educational&room_type=Office
This GETs all rooms with Educational building type and Office room type. However, I am trying to get a list of rooms for multiple composite combinations of {building_type, room_type}.
I am thinking of something like the following:
GET /api/v1/devices?location[]={building_type=Educational,room_type=Office}&location[]={building_type=Commercial,room_type=Office}&location[]={building_type=Educational,room_type=Classroom}
However this doesn't look like standard practice. I am asking for a better way to design this endpoint. I also don't want POST because this query does not change the state
on the server.
Note:
Please note that the following is incorrect, because I need to filter by an array of composite attributes of {building_type, room_type}.
GET /api/v1/devices?building_type[]=Educational&building_type[]=Commercial&room_type[]=Office&room_type=Classroom
It depends on what your backend can handle, but I would try an array of objects, like:
GET /api/v1/devices?location[][building_type]=Educational&location[][room_type]=Office&location[][building_type]=Commercial&location[][room_type]=ClassRoom
Rails 6 parses this like I expect:
"location"=>[{"building_type"=>"Education", "room_type"=>"Office"}, {"building_type"=>"Commercial", "room_type"=>"ClassRoom"}]
But, as this article goes into, libraries don't handle complex object serialization/deserialization into query params consistently. If your backend doesn't like the above, numerically indexing the array should work (though it's more work to construct from your client code):
GET /api/v1/devices?location[0][building_type]=Educational&location[0][room_type]=Office&location[1][building_type]=Commercial&location[1][room_type]=ClassRoom
If you want something that won't be implementation-dependent, you could also consider URL-encoding a JSON string that represents your search query:
GET /api/v1/devices?query=%7B%22locations%22%3A%20%5B%7B%22building_type%22%3A%20%22Educational%22%2C%20%22room_type%22%3A%20%22Office%22%7D%2C%20%7B%20%22building_type%22%3A%20%22Commercial%22%2C%20%22room_type%22%3A%20%22Office%22%7D%5D%7D
Not pretty, but possibly less frustrating.
I've built a RESTful API that fetches employees from the database, Now I want to implement search functionality that filters employees by name and then fetches it. In the frontend, I've fetched employees and then based on user input I'm converting both user input and result from db to lowercase and then matching for similarity? Do you think this problem can be approached in a different way? any other strategies? thanks
Yes, let the database do the comparison for you in SQL. Less resources will be used throughout the entire stack. One of the main features for databases is searching for specific data. Also SQL is case insensitive so no need to do a toLowerCase.
SELECT *
FROM Employees
WHERE name LIKE '%SearchValue%'
Only select the columns you need.
so I'm working with a database that has multiple collections and some of the data overlaps in the collection . In particular I have a collection called app-launches which contains a field called userId and one called users where the _id of a particular object is actually the same as the userId in app-launches. Is it possible to group the two collections together so I can analyze the data? Or maybe match the the userId in app-launches with the _id in users?
There is no definit answer for your question Jeffrey and none of the experts here can tell you to choose which technique over other just by having this information.
After going through various web pages over internet and mongo documentation and understanding the design patterns used in Mongo over a period of time, How I would design it depends on few things which I can try explaining it here in short.
if you have a One-To-One relation then always prefer to choose Embedding over Linking. e.g. User and its address (assuming user has only one address) thus you can utilize the atomicity (without worrying about transactions) as well easily fetch the records without too and fro to bring other information as in the case of Linking (like in DBRef)
If you have One-To-Many relation then you need to consider whether you can do the stuff by using Embedding (prefer this as explained the benefits in point 1). However, embedding would help you if you always want the information altogether e.g. Post/Comments where your requirement is to get the post and all of its comments by postId let say. But think of a situation where you need to get all the comments (and it related posts) which contains some specific tags in comments. in this case you should prefer Linking Because if you go via Embedding route then you would end up getting all the collection of comments for a post and you have to filter the desired comments.
for a Many-To-Many relations I would prefer two separate entities as well another collection for linking them e.g. Product-Category.
-$
I have a physician graph that looks something like this:
The query I use to get data from a WebApi backend looks like this:
var query = new breeze.EntityQuery().from("Physicians")
.expand("ContactInfo")
.expand("ContactInfo.Phones")
.expand("ContactInfo.Addresses")
.expand("PhysicianNotes")
.expand("PhysicianSpecialties")
.where("ContactInfo.LastName", "startsWith", lastInitial).take(5);
(note the ContactInfo is a pseudonym of the People object)
What I find is that If I request Contact.Phones to be expanded, I'll get just phones and no Notes or Specialties. If I comment out the phones I'll get Contact.Addresses and no other collections. If I comment out ContactInfo along with Phones and Addresses I'll get Notes only etc. Essentially, it seems like I can only get one collection at a time.
So, Is this a built in 'don't let the programmer shoot himself in the foot'?? safeguard or do I have to enable something?
OR is this graph too complicated?? should I consider a NoSql object store??
Thanks
You need to put all your expand clauses in a single one like this:
var query = new breeze.EntityQuery().from("Physicians")
.expand("ContactInfo, ContactInfo.Phones, ContactInfo.Addresses, PhysicianNotes, PhysicianSpecialties")
.where("ContactInfo.LastName", "startsWith", lastInitial).take(5);
You can see the documentation here: http://www.breezejs.com/sites/all/apidocs/classes/EntityQuery.html#method_expand
JY told you HOW. But BEWARE of performance consequences ... both on the data tier and over the wire. You can die a miserable death by grabbing too widely and deeply at once.
I saw the take(5) in his sample. That is crucial for restraining a runaway request (something you really must do also on the server). In general, I would reserve extended graph fetches of this kind for queries that pulled a single root entity. If I'm presenting a list for selection and I need data from different parts of the entity graph, I'd use a projection to get exactly what I need to display (assuming, of course, that there is no SQL View readily available for this purpose).
If any of the related items are reference lists (color, status, states, ...), consider bringing them into cache separately in a preparation step. Don't include them in the expand; Breeze will connect them on the client to your queried entities automatically.
Finally, as a matter of syntax, you don't have to repeat the name of a segment. When you write "ContactInfo.Phones", you get both ContactInfos and Phones so you don't need to specify "ContactInfo" by itself.