const Service = require('./service');
const HttpRequestBuilder = require('../http/http-request-builder');
const ServiceRequest = require('./service-request');
const PATH_STATEMENTS = require('./service-paths').PATH_STATEMENTS;
const LoggingUtils = require('../logging/logging-utils');
/**
* Service for executing queries via {@link GetQueryPayload} or
* {@link UpdateQueryPayload}.
*
* @author Mihail Radkov
* @author Svilen Velikov
*/
class QueryService extends Service {
/**
* Instantiates the query service.
*
* @param {Function} httpRequestExecutor used to execute HTTP requests
* @param {Function} parseExecutor function that will parse provided data
*/
constructor(httpRequestExecutor, parseExecutor) {
super(httpRequestExecutor);
this.parseExecutor = parseExecutor;
}
/**
* Executes request to query a repository.
*
* Only POST request with a valid QueryPayload is supported.
*
* @param {GetQueryPayload} payload is an object holding request parameters
* required by the query POST endpoint.
*
* @return {ServiceRequest} a service request that will resolve to a readable
* stream to which the client can subscribe and consume
* the emitted strings or Quads depending on the provided response type as
* soon as they are available.
*
* @throws {Error} if the payload is misconfigured
*/
query(payload) {
const requestBuilder = HttpRequestBuilder.httpPost('')
.setData(payload.getParams())
.setResponseType('stream')
.addAcceptHeader(payload.getResponseType())
.addContentTypeHeader(payload.getContentType());
return new ServiceRequest(requestBuilder,
() => this.executeQuery(payload, requestBuilder));
}
/**
* Executes a query request with the supplied payload and request builder.
*
* @private
*
* @param {GetQueryPayload} payload an object holding request parameters
* required by the query POST endpoint.
* @param {HttpRequestBuilder} requestBuilder builder containing the request
* parameters and data
*
* @return {Promise} promise resolving to parsed query response
*
* @throws {Error} if the payload is misconfigured
*/
executeQuery(payload, requestBuilder) {
return this.httpRequestExecutor(requestBuilder).then((response) => {
const logPayload = LoggingUtils.getLogPayload(response, {
query: payload.getQuery(),
queryType: payload.getQueryType()
});
this.logger.debug(logPayload, 'Queried data');
const parserConfig = {queryType: payload.getQueryType()};
return this.parseExecutor(response.getData(), payload.getResponseType(),
parserConfig);
});
}
/**
* Executes a request with a sparql query against <code>/statements</code>
* endpoint to update repository data.
*
* If <code>contentType</code> is set to
* <code>application/x-www-form-urlencoded</code> then query and request
* parameters from the payload are encoded as query string and sent as request
* body.
*
* If <code>contentType</code> is set to
* <code>application/sparql-update</code> then the query is sent unencoded as
* request body.
*
* @param {UpdateQueryPayload} payload
*
* @return {ServiceRequest} service request that will be resolved if the
* update is successful or rejected in case of failure
*
* @throws {Error} if the payload is misconfigured
*/
update(payload) {
const requestBuilder = HttpRequestBuilder.httpPost(PATH_STATEMENTS)
.setData(payload.getParams())
.addContentTypeHeader(payload.getContentType());
return new ServiceRequest(requestBuilder, () => {
return this.httpRequestExecutor(requestBuilder).then((response) => {
const logPayload = LoggingUtils.getLogPayload(response,
{query: payload.getQuery()});
this.logger.debug(logPayload, 'Performed update');
});
});
}
/**
* @inheritDoc
*/
getServiceName() {
return 'StatementsService';
}
}
module.exports = QueryService;