I am new in Freebase and I have a simple question . I would like to use Freebase KB to find relation between two entities. For example if I have name entities "Washington" and "United States" , I would like to send a query to Freebase and get :
Location/Location/Capital or Null in the case of No relation.
Thank you very much.
If you only want to go one ply out (ie nearest neighbors), this is pretty simple to do using the reflection API if you're using the online version of Freebase. If you're using the bulk downloads, you'll need to work with whatever query engine you're using (probably SPARQL unless you converted the RDF to something else).
If you want to find the shortest path(es) regardless of who far apart they are, it becomes a graph search algorithm.
EDIT: If you only want to find capitols, you can fill in your IDs in this query:
[{
"type": "/location/administrative_division_capital_relationship",
"capital": [{
"id": null
}],
"administrative_division": [{
"id": null
}],
"limit": 1
}]
Note that for Washington, D.C., this will return null because the data isn't in Freebase.
If you need to handle arbitrary properties, you'll need to use reflection. See https://developers.google.com/freebase/mql/ch03#reflection
Related
For school I am creating a deckbuilder website based on Magic the gathering. It's the project that decides if I get my degree or not. Trough the website from Deckbrew I have been able to get data like the following:
[
{
"name": "About Face",
"id": "about-face",
"url": "https://api.deckbrew.com/mtg/cards/about-face",
"store_url": "http://store.tcgplayer.com/magic/urzas-legacy/about-face",
"types": [
"instant"
],
"colors": [
"red"
],
"cmc": 1,
"cost": "{R}",
"text": "Switch target creature's power and toughness until end of turn.",
"formats": {
"commander": "legal",
"legacy": "legal",
"vintage": "legal"
},
"editions": [
{
"set": "Urza's Legacy",
"rarity": "common",
"artist": "Melissa A. Benson",
"multiverse_id": 12414,
"flavor": "The overconfident are the most vulnerable.",
"number": "73",
"layout": "normal",
"price": {
"low": 0,
"average": 0,
"high": 0
},
"url": "https://api.deckbrew.com/mtg/cards?multiverseid=12414",
"image_url": "http://mtgimage.com/multiverseid/12414.jpg",
"set_url": "https://api.deckbrew.com/mtg/sets/ULG",
"store_url": "http://store.tcgplayer.com/magic/urzas-legacy/about-face"
}
]
}
]
It's obvious that it's in jSon format. I have found the way to turn this into objects and the structure of the project is 4-layer MVC with entity framework and C#, which is working (kinda)...The problem is the database. I have been working on it for 2 months now and I am not getting any further. The thing I get stuck on is the database. I have not seen much on how to create databases and that's where it goes wrong. I don't get how to build the database. The creation itself would work if I figured out how to include certain things...
1) Formats: if the card is legal in a format, Formats is filled with: "legacy": "legal", "commander":"legal", ... so only the legal formats are included.
2) Types and colors are just plain arrays of words, but since I'm very bad with databases I don't even know how to figure this one out.
3) Editions is something completely different. It's an array of the object Edition which I believe has to have a table of its own. The problem here is that I thought I needed to use a foreign key but since it's an array of Editions I don't really know how to start doing that either.
4) and then there's Price: It always has 3 values: low, average and high which can be 0 if there's no price known.
So here you have it. To me this database is very complex or maybe I am making it too complex. Is there anybody who can help me to get this database organized so I can get on with my project, because I'm so lost at the moment that I feel I am not going to get this ready by the end of next month and that would be awful.
1: No, you should include all.
2: Table with colors, standard m:n binding table in between mapping the card table with the color table. Not knowing how to make a m:n relationship thing makes me thing you skipped all classes... this is fundamental and basic.
3: Seems like "cardedition" is the main table actually, and everything before is a master type table. Not sure- I don't really do magic at all, so I lack what is called domain knowledge. Are cards changed so multiple editions exist? Why is that an array in json?
3: magic values, 0,1,2,3. What is the question?
To me this database is very complex
I suggest you start from scratch (making things easier) and just have maybe 10 or so tables. Go step by step. Follow what you learned, go to 3rd of 4th normal form and go relational.
Bear with me, as I'm new to API Design and stackoverflow.
For my API design I have three main components:
key/value pairs (a singleton resource)
group (a collection of KVPs)
subgroup (a variation of the corresponding group)
In my API the user should be able to:
create, retrieve, update, and delete KVPs (basic CRUD actions)
organize KVPs into groups and access a listing of those groups
create subgroup variations of the groups that automatically inherit the parent groups' KVPs, and in those subgroups they can edit each KVPs data independently
For example, my Create a New Group request in my documentation looks like this:
{
"group": "age",
"kvps" : [
{
"key": "height",
"value": 5.2
}, {
"key": "weight",
"value": 150
}
],
"subgroups": [
"adult",
"teen",
"baby"
]
}
Using this as an example, I would like the subgroups "adult", "teen", and "baby" to have their own versions of the KVPs "height" and "weight" each with a different value (e.g. adult with a height of 6 and weight of 200, teen with a height of 5.2 and weight 140, etc.) that can be edited independently from each other.
My question: How should I structure my api so that a user could either:
have just editable kvps
have any number of editable kvps organized into any number of groups
or
have any number of editable kvps organized into groups and then further into subgroups
WITHOUT duplicating any of the data?
So far I have a uri structure like this:
/settings/kvps/{kvp_id} (CRUD on one single KVP)
/settings/groups/{group_id} (CRUD on one single group)
/settings/groups/{group_id}/kvps/{kvp_id}
/settings/groups/{group_id}/subgroups/{subgroup_id}
/settings/groups/{group_id}/subgroups/{subgroup_id}/kvps/{kvp_id}
So the kvps have 3 possible URIs, which seems messy to me, and from what I know editing the value of a kvp at
/settings/groups/1/subgroups/1/kvps/1
would also change its value at
/settings/groups/1/subgroups/2/kvps/1
/settings/groups/1/subgroups/3/kvps/1
/settings/groups/1/kvps/1
/settings/kvps/1
and so on, which is the opposite of what I want.
Any ideas?
Once again, I apologize if this is a very simple question that I am way off of, this is my first time designing an API.
I understand that JOINs are either not possible or frowned upon in document databases. I'm coming from a relational database background and trying to understand how to handle such scenarios.
Let's say I have an Employees collection where I store all employee related information. The following is a typical employee document:
{
"id": 1234,
"firstName": "John",
"lastName": "Smith",
"gender": "Male",
"dateOfBirth": "3/21/1967",
"emailAddresses":[
{ "email": "johnsmith#mydomain.com", "isPrimary": "true" },
{ "email": "jsmith#someotherdomain.com", "isPrimary": "false" }
]
}
Let's also say, I have a separate Projects collection where I store project data that looks something like that:
{
"id": 444,
"projectName": "My Construction Project",
"projectType": "Construction",
"projectTeam":[
{ "_id": 2345, "position": "Engineer" },
{ "_id": 1234, "position": "Project Manager" }
]
}
If I want to return a list of all my projects along with project teams, how do I handle making sure that I return all the pertinent information about individuals in the team i.e. full names, email addresses, etc?
Is it two separate queries? One for projects and the other for people whose ID's appear in the projects collection?
If so, how do I then insert the data about people i.e. full names, email addresses? Do I then do a foreach loop in my app to update the data?
If I'm relying on my application to handle populating all the pertinent data, is this not a performance hit that would offset the performance benefits of document databases such as MongoDB?
Thanks for your help.
"...how do I handle making sure that I return all the pertinent information about individuals in the team i.e. full names, email addresses, etc? Is it two separate queries?"
It is either 2 separate queries OR you denormalize into the Project document. In our applications we do the 2nd query and keep the data as normalized as possible in the documents.
It is actually NOT common to see the "_id" key anywhere but on the top-level document. Further, for collections that you are going to have millions of documents in, you save storage by keeping the keys "terse". Consider "name" rather than "projectName", "type" rather than "projectType", "pos" rather than "position". It seems trivial but it adds up. You'll also want to put an index on "team.empId" so the query "how many projects has Joe Average worked on" runs well.
{
"_id": 444,
"name": "My Construction Project",
"type": "Construction",
"team":[
{ "empId": 2345, "pos": "Engineer" },
{ "empId": 1234, "pos": "Project Manager" }
]
}
Another thing to get used to is that you don't have to write the whole document every time you want to update an individual field or, say, add a new member to the team. You can do targeted updates that uniquely identify the document but only update an individual field or array element.
db.projects.update(
{ _id : 444 },
{ $addToSet : "team" : { "empId": 666, "position": "Minion" } }
);
The 2 queries to get one thing done hurts at first, but you'll get past it.
Mongo DB is a document storage database.
It supports High Availability, and Scalability.
For returning a list of all your projects along with project team(details),
according to my understanding, you will have to run 2 queries.
Since mongoDb do not have FK constraints, we need to maintain it at the program level.
Instead of FK constraints,
1) if the data is less, then we can embed the data as a sub document.
2) rather than normalized way of designing the db, in MongoDb we need to design according to the access pattern. i.e. the way we need to query the data more likely. (However time for update is more(slow), but at the user end the performance mainly depends on read activity, which will be better than RDBMS)
The following link provides a certificate course on mongo Db, free of cost.
Mongo DB University
They also have a forum, which is pretty good.
This question already has answers here:
MongoDB relationships: embed or reference?
(10 answers)
Closed 8 years ago.
I started my studies in MongoDB recently and I didn't understand much better how we make the relationship between the entities that we have in the system.
So, as I am used to make this relationships in the SQL way, I get kind of confused when I change the logic to think in NoSQL way.
I saw that MongoDB has to types of modeling: Embedded and Referenced.
If I understand correct, Referenced is like we do in SQL:
Example: 1-to-N
Create two tables to represent the entities, like User and Address.
Create an user object and an address object
Put the Address ID into an user object
{
"_id":ObjectId("52ffc33cd85242f436000001"),
"contact": "987654321",
"dob": "01-01-1991",
"name": "Tom Benzamin",
"address_ids": [
ObjectId("52ffc4a5d85242602e000000"),
ObjectId("52ffc4a5d85242602e000001")
]
}
And the Embedded:
Create just one table, in this case User.
Create an user object and inside of it put the address object:
{
"_id":ObjectId("52ffc33cd85242f436000001"),
"contact": "987654321",
"dob": "01-01-1991",
"name": "Tom Benzamin",
"address": [
{
"building": "22 A, Indiana Apt",
"pincode": 123456,
"city": "Los Angeles",
"state": "California"
},
{
"building": "170 A, Acropolis Apt",
"pincode": 456789,
"city": "Chicago",
"state": "Illinois"
}]
}
So, my questions are:
To use the best features of a NoSQL Database like MongoDB, I have to use Embedded Modeling ?
In Embedded Modeling I just create only one Entity and the entity that is inside, the address object in this case, will not have an ID, since I didn't create a table ?
You're right with MongoDB. As you said, you have two ways to stock data.
The best way depends on what you need.
If your address object is going to be used somewhere else, put it in another table, if not, you can put it directly in your object.
If you're using MongoDB with NodeJS, you can use MongooseJS. It's a kind of framework which has the particularity to define schemas for your mongodb objects. It works fine particulary with embedded objects because it add an objectId for every object you embed.
I'm currently designing and implementing a RESTful API in PHP.
The API allows users to search for hotels.
A simplified example of the search request is:
GET hotels/searchresults?location=<location> #collection of hotels within location
The response also contains some meta information about the returned collection.
The basic structure of the response is:
“meta": {
“totalNrOfHotels": 100,
"totalNrAvailable": 80
},
“hotels": [
{
“id": 123,
“name": "Hotel A"
},
{
“id": 135,
“name": "Hotel B"
},
...
]
This resource also supports pagination:
GET hotels/searchresults?location=<location>&offset=0&limit=20
Now, there are a few filters that can be applied to the search results, e.g. stars, rating score.
For example, if I want just 2 star hotels, I can query:
GET hotels/searchresults?location=<location>&offset=0&limit=20&stars=2
Now, in the user interface for filtering, it is common to display the number of options available per filter setting:
In my opinion, these numbers can be seen as meta data about the search query. So, we could add an extra field to the meta in the response:
“meta": {
“totalNrOfHotels": 100,
"totalNrAvailable": 80
“filterNrs": {
"stars”: {
“1": 1,
“2”: 9,
“3”: 39,
“4”: 12,
“5”: 11,
“none”: 9
}
}
},
“hotels": [
{“id": 123,
“name": "Hotel A"
},
{“id": 135,
“name": "Hotel B"
},
...
]
So, I have two questions:
Should this “filterNrs” property sit in the meta section, as proposed above? To me, it doesn’t make sense to be a separate resource/request
How can we deal with the fact that this can slow down the query? I’d prefer to make the “filterNrs” field optional. We are thinking of using a “metaFields" parameter to allow the user to specify which fields in the meta she would like to recieve. We already support this for the hotels returned, with a “fields” parameter. (Similar to: https://developers.google.com/youtube/2.0/developers_guide_protocol_partial). Alternatively, we put this field filterNrs (or the full meta info) in a separate resource, something like hotels/searchresults/meta. From a developers perspective would you prefer to have this split into multiple resources or have a single resource with the option to show full or partial meta information?
Does the number rated per star count varies? For example, do I get different "filterNrs" for the queries below?
GET hotels/searchresults?location=1
GET hotels/searchresults?location=2
I would expect such filters to be contextual, so different locations would return different numbers per star count, which indicates this is some form of contextual information related to the query.
Otherwise if the results are global this indicates it's a separate resource. If it's a separate resource scenario, you can use links to access the numbers and other details about it:
“meta": {
“totalNrOfHotels": 100,
"totalNrAvailable": 80
“filterNrs": {
"stars”: {
"options" : ["1", "2", "3", "4", "5", "none"],
"details" : "http://example.com/stars"
}
}
},