INSERT/DELETE/UPDATE query using SPARQLWrapper

Question

Although I have gone through lot of examples on the web explaining the use of python SPARQLWrapper using SELECT statements for fetching data from sesame triple store, but not sure how can we INSERT/DELETE/UPDATE statements in sesame using it. Can any of you please guide in this regard.

Thanks

Aggie

Answer 1

The SPARQL queries are send as GET request, but the UPDATE (like INSERT, DELETE, etc.) requires the query be send as a POST request. Just add the following line before sparql.query()

sparql.method = 'POST'

Also, the url for update is different from the query. The update is based on workbench and not sesame url. For example, if the query url is:

http://localhost:8080/openrdf-sesame/repositories/test/

or

http://localhost:8080/openrdf-workbench/repositories/test/query

then the update url would be:

http://localhost:8080/openrdf-workbench/repositories/test/update

Therefore, the UPDATE/INSERT request should look like:

queryString = "INSERT DATA { GRAPH <http://example.com/> { "b" a "c". } }" 
sparql = SPARQLWrapper("http://localhost:8080/openrdf-workbench/repositories/test/update")

sparql.setQuery(queryString) 
sparql.method = 'POST'
sparql.query()

Remiss

Answer 2

This is not particularly clear from the docs, but I think you can just execute an update statement in the same way that you execute a query:

queryString = "DELETE WHERE { ?s ?p ?o. }" 
sparql = SPARQLWrapper("http://localhost:8080/openrdf-sesame/repositories/test/statements")

sparql.setQuery(queryString) 
ret = sparql.query()

In the case of Sesame, one thing to keep in mind is that the URL for the update endpoint (repositories/<repId>/statements) is not the same as the URL for the query endpoint (repositories/<repId>). See the Sesame protocol docs for details.

Melchizedek

this URL gives error, SPARQLWrapper.SPARQLExceptions.EndPointInternalError: EndPointInternalError: endpoint returned code 500 and response. org.openrdf.workbench.exceptions.BadRequestException: Unconfigured path: /statements. I have tried lot of other URL e.g. (localhost:8080/openrdf-sesame/repositories/test/remove") but no success. Thanks for answering. – Aggie

Did you replace the test bit in the url with the actual id of your repository? I've added a link to the Sesame protocol docs to the answer, which gives more details. – Melchizedek

Also: a Workbench exception? The Workbench shouldn't play any part in this setup at all.. – Melchizedek

Ah! I was doing mistake in <repID>. Now my URL is localhost:8080/openrdf-sesame/repositories/sample/statements and when I run it gives following error: urllib2.HTTPError: HTTP Error 406: Not Acceptable. I have also visited sesame protocol docs and trying to understand the reason behind this error. I am extremely thankful for your help. – Aggie

Sesame sends a HTTP 406 error when the client does not specify an acceptable response format. So this looks like a problem in the SPARQLWrapper. If I were you I'd get in touch with the developers directly (I believe they have a mailinglist). – Melchizedek