Re: [dotNetRDF-Develop] Building SPARQL programmatically

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I'm all over it :)

Have a look at my pull request [1]. I have extracted an interface and
changed how the builder is initialized. Write what you think, I'm
still not convinced it's ideal.

For now it goes like that:

// start builder statically (constructor private)
// more factory methods would come
IQueryBuilder queryBuilder = QueryBuilder.SelectAll().Where(triplePattern);

SparqlQuery query1 = queryBuilder.GetExecutableQuery();
SparqlQuery query2 = queryBuilder.GetExecutableQuery();

// I added test for this
Assert.AreNotSame(query1, query2);

There are three issues however:
1. To change the API the least I made QueryBuilder also inherit
INodeFactory and use the underlying SparqlQuery as decorated
implementor. This again obfuscates the usage. Can think of a better
solution?
2. The copy now fails in select tests 1 and 2 on creating
GraphPattern. Is it just safe to check for null and skip that
constructor?
3. I had to remove a bunch of invalid usings after merging with latest
trunk changes

Lastly I think that QueryBuiler chould contain just one overload for
eg. the Where method and there could be an extension class, which
defines handy overloads. I think it's how some of the dotNetRDF API
works already. This needs to be thought over though.

Thanks
Tom

[1] https://bitbucket.org/dotnetrdf/dotnetrdf/pull-request/1/changes-in-querybuilder-prototype

On Tue, Sep 25, 2012 at 12:43 AM, Rob Vesse <rv...@do...> wrote:
> Yes I think I actually like that approach better
>
> I did say it was a rough cut, send me a pull request if you make a start
> on it otherwise I'll get to it when I get to it
>
> Might be nice to have that as our major new feature for 0.8.0 since I plan
> on getting 0.7.2 out Wednesday time allowing
>
> Rob
>
> On 9/24/12 1:32 PM, "Tomasz Pluskiewicz" <tom...@gm...>
> wrote:
>
>>Hi Rob
>>
>>The QueryBuilder starts very promising. Way better than the Algebra API.
>>
>>However I'm not convinced with the extension methods way. What I could
>>suggest is a specialized builder class which holds the query inside
>>and the user can retrieve it whenever he is done with building.
>>Something along the below:
>>
>>public class QueryBuilder : IQueryBuilder
>>{
>>  private SparqlQuery _query = new SparqlQuery();
>>
>>  // such constructor only as a suggestion
>>  // could also create factory methods for the query types
>>  public QueryBuilder(SparqlQueryType queryType)
>>  {
>>     _query.QueryType = queryType;
>>  }
>>
>>  // Now all methods are simmilar but not extension
>>  // and will return self. For example:
>>  public IQueryBuilder Where(IEnumerable<Triple> ts)
>>  {
>>    foreach (Triple t in ts)
>>    {
>>      _query = _query.Where(t.Subject, t.Predicate, t.Object);
>>    }
>>   return this;
>>  }
>>
>>  public SparqlQuery GetExecutableQuery()
>>  {
>>    // not sure the Copy() is required
>>    // the internal API forbids any changes to the underlying query anyway
>>    // but shall that change any time, it could lead to unexpected results
>>    return _query.Copy();
>>  }
>>}
>>
>>I'm suggesting this, because currently the SparqlQuery has quite a few
>>public getters and methods and at first it was very obscure what
>>functionality the QueryBuilder actually provides.
>>
>>Also notice the IQueryBuilder interface. I think it would be
>>beneficial to let the users actuall mock the builder and have the
>>calls verified in unit tests. Last but not least, there could be not
>>one but multiple interfaces implemented by the QueryBuilder class,
>>which gives us power to order some of the calls if we ever need such a
>>feature.
>>
>>It's already 10:30PM here so I won't be reworking the code today.
>>Tomorrow maybe, depending on your thoughts on all this :).
>>
>>Tom
>>
>>On Mon, Sep 24, 2012 at 7:20 PM, Rob Vesse <rv...@do...> wrote:
>>> Off the top of my head it should look something like this, assuming you
>>> create the URIs as INode instances first:
>>>
>>> ISparqlAlgebra algebra = new Select(
>>>   new Filter(
>>>    new Join(
>>>     new LeftJoin(
>>>      new LeftJoin(
>>>       new BGP(),
>>>       new BGP(new TriplePattern(new VariablePattern("?item"), new
>>> NodeMatchPattern(rdfType), new NodeMatchPattern(someClass)))
>>>      ),
>>>      new BGP(new TriplePattern(new VariablePattern("?item"), new
>>> NodeMatchPattern(rdfType), new NodeMatchPattern(someOtherClass)))
>>>     ),
>>>     new BGP(new TriplePattern(new VariablePattern("?item"), new
>>> NodeMatchPattern(foafName), new VariablePattern("?itemName")))
>>>    ),
>>>    new UnaryExpressionFilter(new LangMatchesFunction(new
>>>LangFunction(new
>>> VariableTerm("itemName")), new ConstantTerm(en)))
>>>   ),
>>>   new String[] { "item" });
>>>
>>> Not the prettiest thing to build, see the QueryBuilder class [1] on the
>>> fluent-query [2] branch for an initial rough cut of a more user friendly
>>> fluent style API, see the unit tests in that commit for some examples of
>>> building queries
>>>
>>> Hopefully that style of API will be much more readable than the above
>>>and
>>> much more user friendly
>>>
>>> Rob
>>>
>>> [1]
>>>
>>>https://bitbucket.org/dotnetrdf/dotnetrdf/changeset/f0654d04f2612d6e215ff
>>>17
>>> d166ba99c74e781af
>>> [2]
>>>
>>>https://bitbucket.org/dotnetrdf/dotnetrdf/changesets/tip/branch(%22fluent
>>>-q
>>> uery%22)
>>>
>>>
>>> On 9/24/12 5:40 AM, "Tomasz Pluskiewicz" <tom...@gm...>
>>> wrote:
>>>
>>>>Hello again
>>>>
>>>>I tried to build some algebra programmatically but I failed miserably :)
>>>>
>>>>Could you please as an example help me with expressing the below
>>>>SPARQL in Algebra API?
>>>>
>>>>SELECT ?item
>>>>{
>>>>  OPTIONAL { ?item a  ex:someClass . }
>>>>  OPTIONAL { ?item a  ex:someOtherClass . }
>>>>  ?item foaf:name ?itemName
>>>>  FILTER( langMatches( lang(?itemName), "en" ))
>>>>}
>>>>
>>>>This should give me enough insight to get up to speed with the API.
>>>>
>>>>Thanks,
>>>>Tom
>>>>
>>>>On Sat, Sep 22, 2012 at 7:02 PM, Tomasz Pluskiewicz
>>>><tom...@gm...> wrote:
>>>>> Also are there any introductory examples on creating SPARQL Algebra.
>>>>> It could be the way to go for my initially. Are there many scenarios
>>>>> when it would be impossible to convert it to a query?
>>>>>
>>>>> Tom
>>>>>
>>>>> On Sat, Sep 22, 2012 at 11:30 AM, Tomasz Pluskiewicz
>>>>> <tom...@gm...> wrote:
>>>>>> Thanks Rob
>>>>>>
>>>>>> I could look into it. Please point me int the right direction in the
>>>>>> code where the internal API is located.
>>>>>>
>>>>>> Tom
>>>>>>
>>>>>> On Fri, Sep 21, 2012 at 10:26 PM, Rob Vesse <rv...@do...>
>>>>>>wrote:
>>>>>>> Hey Tom
>>>>>>>
>>>>>>> Right now it's somewhat limited, you can build the algebra
>>>>>>> programmatically and try and convert it back to a query with the
>>>>>>>AsQuery()
>>>>>>> method but that isn't guaranteed to work (some algebras can't be
>>>>>>>converted
>>>>>>> back into queries).  Otherwise you have to generate a string and
>>>>>>>then
>>>>>>> parse it.
>>>>>>>
>>>>>>> Most of the SparqlQuery API is protected internal/private, I have a
>>>>>>>To Do
>>>>>>> item to add a public fluent style API for building queries that I
>>>>>>>will
>>>>>>> likely do for the next release if that helps.  I/you can start
>>>>>>>building
>>>>>>> that out in a feature branch if that would solve your issue?
>>>>>>>
>>>>>>> Rob
>>>>>>>
>>>>>>> On 9/21/12 11:39 AM, "Tomasz Pluskiewicz"
>>>>>>><tom...@gm...>
>>>>>>> wrote:
>>>>>>>
>>>>>>>>Hi
>>>>>>>>
>>>>>>>>Please tell me what are the options for building SPARQL
>>>>>>>>programatically with dotNetRDF? Is there any such API?
>>>>>>>>
>>>>>>>>Regards,
>>>>>>>>Tom
>>>>>>>>
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