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query.service.ts
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Fri, May 17, 02:15

query.service.ts
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import { Injectable } from '@angular/core';
import { Parser, Generator, Wildcard } from 'sparqljs';
import {HttpClient, HttpHeaders} from '@angular/common/http';
@Injectable()
export class QueryService {
constructor(private http: HttpClient) {
}
/**
* Gets the data from an endpoint via http post
*
* @param baseUrl: The url of the endpoint.
* @param query: The query to run.
* @param queryType: "CONSTRUCT" or "QUERY"
* @returns the response.
*/
public getData(baseUrl: string, query: string, queryType?: string ) {
let httpOptions;
if (queryType === 'CONSTRUCT') {
// A construct does contain a text as response, not a json, so responseType must be 'text' to avoid parse errors
httpOptions = { headers: new HttpHeaders({'Content-Type': 'application/sparql-query', 'Accept': 'text/turtle'}),
responseType: 'text'};
return this.http.post(baseUrl, query, httpOptions).toPromise();
} if (queryType === 'SELECT' || queryType === 'ASK') {
httpOptions = { headers: new HttpHeaders({ 'Content-Type': 'application/sparql-query',
'Accept': 'application/sparql-results+json; charset=UTF-8'})};
return this.http.post(baseUrl, query, httpOptions).toPromise();
}
}
public updateData(baseUrl: string, data: string) {
let query = `INSERT DATA {${data}}`;
console.log('query', query);
let httpOptions = { headers: new HttpHeaders({ 'Content-Type': 'application/sparql-update',
'Authorization': 'Basic bmlldHpzY2hlX3VzZXI6bmlldHpzY2hl',
'Accept': 'application/sparql-results+json; charset=UTF-8'}), method: 'POST', body: query};
this.http.post(baseUrl, query, httpOptions).toPromise().then(fuu => console.log(fuu) );
}
/**
* Gets a text file by its name from the directory assets/queries.
*
* @param filename The name of the file + file name extension.
* @returns the text of the file.
*/
public getQueryfromFilename(filename) {
return this.http.get('../assets/queries/' + filename, {responseType: 'text'}).toPromise();
}
/**
* getQueryForItem()
* Parametrizes a given baseQuery with a iri passed, so the iri will be the resource of the where clause
*
* @param subjectIri: The iri of the selected resource
* @param baseQuery: name of the query to parametrize
* @param propertyIri: The iri of the selected property
* @param objectIri: The iri of the selected object
* @returns the query for the resource.
*/
public parametrizeQueryWithItem(baseQuery: string, subjectIri?: string, propertyIri?: string, objectIri?: string): string {
let qParametrizer = new TlnQueryParametrizer(baseQuery);
qParametrizer.parametrize(subjectIri, propertyIri, objectIri);
return qParametrizer.writeOut();
}
}
export class TlnQueryParametrizer {
parsedQuery;
parser: Parser;
sparqlGenerator = new Generator({});
constructor(baseQuery: string) {
this.parser = new Parser();
this.parsedQuery = this.parser.parse(baseQuery);
console.log(this.parsedQuery);
}
parametrize(subjectIri?: string, predicateIri?: string, objectIri?: string) {
this.setSubject(subjectIri);
this.setPredicate(predicateIri);
this.setObject(objectIri);
}
setSubject(subjectIri: string): void {
if (!subjectIri || subjectIri === '') { return }
this.parsedQuery.where[0].triples[0].subject = {'termType': 'NamedNode', 'value': decodeURI(subjectIri) };
if (this.parsedQuery.queryType === 'CONSTRUCT') { // in case of constructs we also change the property
this.parsedQuery.template[0].subject = {'termType': 'NamedNode', 'value': decodeURI(subjectIri) };
}
}
setPredicate(predicateIri: string): void {
if (!predicateIri || predicateIri === '') { return }
this.parsedQuery.where[0].triples[0].predicate = {'termType': 'NamedNode', 'value': decodeURI(predicateIri) };
if (this.parsedQuery.queryType === 'CONSTRUCT') { // in case of constructs we also change the property
this.parsedQuery.template[0].predicate = {'termType': 'NamedNode', 'value': decodeURI(predicateIri) };
}
}
setObject(objectIri: string): void {
if (!objectIri || objectIri === '') { return }
this.parsedQuery.where[0].triples[0].object = {'termType': 'NamedNode', 'value': decodeURI(objectIri) };
if (this.parsedQuery.queryType === 'CONSTRUCT') { // in case of constructs we also change the property
this.parsedQuery.template[0].object = {'termType': 'NamedNode', 'value': decodeURI(objectIri) };
}
}
writeOut() {
return this.sparqlGenerator.stringify(this.parsedQuery);
}
}

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