I am trying to query a specific RDF file. I need this solution for my work.
The file I have to work with is:
https://github.com/iliriani/Test/blob/main/Notebook.rdf
I am trying to get somehow all the attributes ( <attribute'>...<'name> ) of a given class( <class'>...<name'> ) within this model. But cannot find the right query!
For instance, I want to get all attributes of class "Teacher", it should return me:
id
Emri
Mbiemri
Lendet
Evaluations
User
Hope for your support.
Related
I have the following sample KB:
(:Ethan, :rel1, :Peter)
(:Ethan, :rel2, :son)
(:Sienna, :rel3, :Josie)
(:Sienna, :rel4, :daughter)
(:Josie, :rel5, :Peter)
(:Josie, :rel6, :wife)
Now I need to find a property path (all related triples) from :son to :wife. What would be the SPARQL query for that?
The result should be like this:
(:Ethan, :rel2, :son)
(:Ethan, :rel1, :Peter)
(:Josie, :rel5, :Peter)
(:Josie, :rel6, :wife)
I have three models:
class Customer(models.Model):
pass
class IssueType(models.Model):
pass
class IssueTypeConfigPerCustomer(models.Model):
customer=models.ForeignKey(Customer)
issue_type=models.ForeignKey(IssueType)
class Meta:
unique_together=[('customer', 'issue_type')]
How can I find all tuples of (custmer, issue_type) where there is no IssueTypeConfigPerCustomer object?
I want to avoid a loop in Python. A solution which solves this in the DB would be preferred.
Background: for every customer and for every issue-type, there should be a config in the DB.
If you can afford to make one database trip for each issue type, try something like this untested snippet:
def lacking_configs():
for issue_type in IssueType.objects.all():
for customer in Customer.objects.filter(
issuetypeconfigpercustomer__issue_type=None
):
yield customer, issue_type
missing = list(lacking_configs())
This is probably OK unless you have a lot of issue types or if you are doing this several times per second, but you may also consider having a sensible default instead of making a config object mandatory for each combination of issue type and customer (IMHO it is a bit of a design-smell).
[update]
I updated the question: I want to avoid a loop in Python. A solution which solves this in the DB would be preferred.
In Django, every Queryset is either a list of Model instances or a dict (values querysets), so it is impossible to return the format you want (a list of tuples of Model) without some Python (and possibly multiple trips to the database).
The closest thing to a cross product would be using the "extra" method without a where parameter, but it involves raw SQL and knowing the underlying table name for the other model:
missing = Customer.objects.extra(
select={"issue_type_id": 'appname_issuetype.id'},
tables=['appname_issuetype']
)
As a result, each Customer object will have an extra attribute, "issue_type_id", containing the id of one IssueType. You can use the where parameter to filter based on NOT EXISTS (SELECT 1 FROM appname_issuetypeconfigpercustomer WHERE issuetype_id=appname_issuetype.id AND customer_id=appname_customer.id). Using the values method you can have something close to what you want - this is probably enough information to verify the rule and create the missing records. If you need other fields from IssueType just include them in the select argument.
In order to assemble a list of (Customer, IssueType) you need something like:
cross_product = [
(customer, IssueType.objects.get(pk=customer.issue_type_id))
for customer in
Customer.objects.extra(
select={"issue_type_id": 'appname_issuetype.id'},
tables=['appname_issuetype'],
where=["""
NOT EXISTS (
SELECT 1
FROM appname_issuetypeconfigpercustomer
WHERE issuetype_id=appname_issuetype.id
AND customer_id=appname_customer.id
)
"""]
)
]
Not only this requires the same number of trips to the database as the "generator" based version but IMHO it is also less portable, less readable and violates DRY. I guess you can lower the number of database queries to a couple using something like this:
missing = Customer.objects.extra(
select={"issue_type_id": 'appname_issuetype.id'},
tables=['appname_issuetype'],
where=["""
NOT EXISTS (
SELECT 1
FROM appname_issuetypeconfigpercustomer
WHERE issuetype_id=appname_issuetype.id
AND customer_id=appname_customer.id
)
"""]
)
issue_list = dict(
(issue.id, issue)
for issue in
IssueType.objects.filter(
pk__in=set(m.issue_type_id for m in missing)
)
)
cross_product = [(c, issue_list[c.issue_type_id]) for c in missing]
Bottom line: in the best case you make two queries at the cost of legibility and portability. Having sensible defaults is probably a better design compared to mandatory config for each combination of Customer and IssueType.
This is all untested, sorry if some homework was left for you.
I have been trying to figure out how to perform specific query for quite a while, and have been through several attempts to no avail. Below is an example to illustrate the problem:
There are 2 types of nodes, users and documents. Users can have a relationship type labeled collaborates_with, and can be related to documents as can_edit, created, or have no relationship.
Now what I would like to do is perform a query that will return all documents that fit a set of search criteria (say created within the last week), AND if the document was created by a collaborator of a specific user, return that relationship.
To fetch the documents and the creator of each document, the query is pretty straight forward:
MATCH (doc:document)<-[rel:created]-(u1:user)
WHERE doc.createddate > TIMESTAMP_FOR_ONE_WEEK_AGO
RETURN doc, u1
where TIMESTAMP_FOR_ONE_WEEK_AGO is just the unix timestamp corresponding to right now minus 7*24*60*60*1000.
The difficulty comes when trying to conditionally return the relationship with the current user.
I have played with CASE statements and OPTIONAL MATCH, but nothing seems to get what I'm looking for. One example of my attempts:
MATCH (doc:document)<-[rel:created]-(u1:user)
WHERE doc.createddate > TIMESTAMP_FOR_ONE_WEEK_AGO
WITH doc, u1
MATCH u1-[rel:collaborates_with]-(me:user)
WHERE me.username = MY_USERNAME
RETURN doc, rel
This, however, only returns the documents that have been created by one of my collaborators. Instead, I'd like it to return ALL of the documents fitting the search, and only return the relationship if it exists.
Has anyone been able to perform something like this?
NOTE: This question is similar, but not quite what I'm running into.
Optional Match should do it:
MATCH (doc:document)<-[rel:created]-(u1:user)
WHERE doc.createddate > TIMESTAMP_FOR_ONE_WEEK_AGO
WITH doc, u1 //find all docs that satisfy search conditions
OPTIONAL MATCH u1-[rel:collaborates_with]-(me:user) //optionally see if the creator collaborates with me
WHERE me.username = MY_USERNAME
RETURN doc, rel
I have the following entities in Entity Framwork 5 (C#):
OrderLine - Id, OrderId, ProductName, Price, Deleted
Order - Id, CustomerId, OrderNo, Date
Customer - Id, CustomerName
On the order search screen the user can enter the following search values:
ProductName, OrderNo, CustomerName
For Example they might enter:
Product Search Field: 'Car van bike'
Order Search Field: '100 101 102'
Customer Search Field: 'Joe Jack James'
This should do a OR search (ideally using linq to entities) for each entered word, this example would output the following where sql.
(ProductName like 'Car' Or ProductName like 'van' Or ProductName like 'bike') AND
(OrderNo like '100' Or OrderNo like '101' Or OrderNo like '102') AND
(CustomerName like 'Joe' Or CustomerName like 'Jack' Or CustomerName like 'James')
I want to do this using linq to entities, i am guessing this would need to be some sort of dynamic lambda builder as we don't know how many words the user might enter into each field.
How would i go about doing this, i have had a quick browse but cant see anything simple.
You can build a lambda expression using Expression Trees . What you need to do is split the value and build the expression . Then you can convert in in to a lambda expression like this,
var lambda = Expression.Lambda<Func<object>>(expression);
Here is an example
There are 2 basic approaches to Dynamic Expressions and Queries in LINQ.
3 if you count using Json as the approach to get a lambda expression. => Akash Kava post
a) String Dynamic Lambda
System.Linq.Dynamic can be found at following links
http://msdn.microsoft.com/en-US/vstudio/bb894665.aspx
http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx
http://www.scottgu.com/blogposts/dynquery/dynamiclinqcsharp.zip
b) Build Expression trees
More powerful but harder to master...
Build expressions trees with code found here:
http://msdn.microsoft.com/en-us/library/system.linq.expressions.aspx
an alternate approach is predicate builder but it isnt really that dynamic.
but can deal with the OR type scenario you give as example.
http://www.albahari.com/nutshell/predicatebuilder.aspx
I would recomend to go slightly different way from answers above and use EntitySQL as it is trivial to build SQL-like string with dynamic conditions.
http://msdn.microsoft.com/en-us/library/bb738683.aspx
Disclaimer: I am author of Entity REST SDK.
You can look at Entity REST SDK at http://entityrestsdk.codeplex.com
You can query using JSON syntax as shown below,
/app/entity/account/query?query={AccountID:2}&orderBy=AccountName
&fields={AccountID:'',AcccountName:''}
You can use certain extensions provided to convert JSON to lambda.
And here is details of how JSON is translated to Linq. http://entityrestsdk.codeplex.com/wikipage?title=JSON%20Query%20Language&referringTitle=Home
Current Limitations of OData v3
Additionally, this JSON based query is not same as OData, OData does not yet support correct way to search using navigation properties. OData lets you search navigation property inside a selected entity for example Customer(1)/Addresses?filter=..
But here we support both Any and Parent Property Comparison as shown below.
Example, if you want to search for List of Customers who have purchased specific item, following will be query
{ 'Orders:Any': { 'Product.ProductID:==': 2 } }
This gets translated to
Customers.Where( x=> x.Orders.Any( y=> y.Product.ProductID == 2))
There is no way to do this OData as of now.
Advantages of JSON
When you are using any JavaScript frameworks, creating query based on English syntax is little difficult, and composing query is difficult. But following method helps you in composing query easily as shown.
function query(name,phone,email){
var q = {};
if(name){
q["Name:StartsWith"] = name;
}
if(phone){
q["Phone:=="] = phone;
}
if(email){
q["Email:=="] = email;
}
return JSON.stringify(q);
}
Above method will compose query and "AND" everything if specified. Creating composable query is great advantage with JSON based query syntax.
I'm currently trying to create an Endeca query using the Java API for a URLENEQuery. The current query is:
collection()/record[CONTACT_ID = "xxxxx" and SALES_OFFICE = "yyyy"]
I need it to be:
collection()/record[(CONTACT_ID = "xxxxx" or CONTACT_ID = "zzzzz") and
SALES_OFFICE = "yyyy"]
Currently this is being done with an ERecSearchList with CONTACT_ID and the string I'm trying to match in an ERecSearch object, but I'm having difficulty figuring out how to get the UrlENEQuery to generate the or in the correct fashion as I have above. Does anyone know how I can do this?
One of us is confused on multiple levels:
Let me try to explain why I am confused:
If Contact_ID and Sales_Office are different dimensions, where Contact_ID is a multi-or dimension, then you don't need to use EQL (the xpath like language) to do anything. Just select the appropriate dimension values and your navigation state will reflect the query you are trying to build with XPATH. IE CONTACT_IDs "ORed together" with SALES_OFFICE "ANDed".
If you do have to use EQL, then the only way to modify it (provided that you have to modify it from the returned results) is via string manipulation.
ERecSearchList gives you ability to use "Search Within" functionality which functions completely different from the EQL filtering, though you can achieve similar results by using tricks like searching only specified field (which would be separate from the generic search interface") I am still not sure what's the connection between ERecSearchList and the EQL expression above?
Having expressed my confusion, I think what you need to do is to use String manipulation to dynamically build the EQL expression and add it to the Query.
A code example of what you are doing would be extremely helpful as well.