Graphdb.js node.js 一个 server.repository 通过 Rest API 连接多个查询

Question

我正在使用 nodejs 和 graphdbjs。我的问题是我是否可以激活一个存储库并设置两个查询（在本例中为有效负载），它们将作为 REST API 按需运行。例如

const server = new ServerClient(serverConfig);
const readTimeout = 30000;
const writeTimeout = 30000;
const repositoryClientConfig = new RepositoryClientConfig(['http://localhost:7200/repositories/V2'], {}, '', readTimeout, writeTimeout);
server.getRepository('V2',repositoryClientConfig).then(repository => {  
  repository.registerParser(new SparqlJsonResultParser());

    const payload = new GetQueryPayload()
      .setQuery('select * where {?s ?p ?o}')
      .setQueryType(QueryType.SELECT)
      .setResponseType(RDFMimeType.SPARQL_RESULTS_JSON)
      .setLimit(100);
    repository.query(payload).then((stream) => {
       stream.on('data', (bindings) => {
            var test = Object.values(bindings);
         var element = {id: test[0].id.replace(/['"]+/g, ''), name: test[1].id.replace(/['"]+/g, '')}
        });
        stream.on('end', () => {          
        restapp.get('/getallIDs', function(req,res)  {
        res.send(element);
        });
        restapp.listen(3000, function () {
             console.log('App listening on port 3000!');
        });
        }); 
});




const payload2 = new GetQueryPayload()
  .setQuery('select * where {?s ?p ?o}')
  .setQueryType(QueryType.SELECT)
  .setResponseType(RDFMimeType.SPARQL_RESULTS_JSON)
  .setLimit(100);
  repository2.query(payload2).then((stream2) => {
    stream2.on('data', (bindings2) => {
    var test2 = Object.values(bindings2);
    var i2=0;
    test2.forEach(function(key,value){
      if (i2%2==1){
      return true;}
      var element2 = {id: test2[0].id.replace(/['"]+/g, ''), name: test2[1].id.replace(/['"]+/g, '')}
      i++;
      head2.table.push(element2);
    });       
    });
    stream2.on('end', () => {
    restapp2.get('/getidby', function(req,res)  {
      res.send(head2);
    });
    restapp2.listen(3000, function () {
       console.log('App listening on port 3000!');
    });
    });

我只想有一个会话和多个有效负载，如果用户点击正确的 url，那么它 returns 就像 json。截至目前，我收到无法解释的错误：

{"level":"error","time":1572863035018,"name":"RDFRepositoryClient","repositoryUrl":"http://localhost:7200/repositories/V2","msg":"Cannot retry execution","v":1}
Error: Request failed with status code 400
    at createError (/home/estathop/eclipse-workspace/test/node_modules/axios/lib/core/createError.js:16:15)
    at settle (/home/estathop/eclipse-workspace/test/node_modules/axios/lib/core/settle.js:17:12)
    at RedirectableRequest.handleResponse (/home/estathop/eclipse-workspace/test/node_modules/axios/lib/adapters/http.js:211:9)
    at RedirectableRequest.emit (events.js:210:5)
    at RedirectableRequest._processResponse (/home/estathop/eclipse-workspace/test/node_modules/follow-redirects/index.js:269:10)
    at ClientRequest.RedirectableRequest._onNativeResponse (/home/estathop/eclipse-workspace/test/node_modules/follow-redirects/index.js:50:10)
    at Object.onceWrapper (events.js:300:26)
    at ClientRequest.emit (events.js:210:5)
    at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:583:27)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:115:17)

对实现我想要做的事情有什么帮助吗？我的下一步是从 restful 服务获取 id 并相应地形成有效负载谢谢，抱歉，如果我的问题是假的，但我是这个领域的新手

Answer 1

据我所知，您要实现的目标没有概念上的问题。现在根据错误，我认为这可能与您对其余部分执行的 GET 请求有关 api restapp.get('/getallIDs', function(req,res) {...} 您能否确认 repository.query(payload) 调用 returns 是正确的响应？我猜你可以简单地在 stream.on('data') 之前放置一个记录器，看看它是否被打印出来，这将确认 graphdbjs 请求可能是正确的。我可以给你一个稍微改进但仍然相似的例子，它似乎正确地流式传输查询结果：

const {ServerClient, ServerClientConfig} = require('graphdbjs').server;
const {RepositoryClientConfig} = require('graphdbjs').repository;
const {RDFMimeType} = require('graphdbjs').http;
const {SparqlJsonResultParser} = require('graphdbjs').parser;
const {GetQueryPayload, QueryType} = require('graphdbjs').query;

const serverConfig = new ServerClientConfig('http://localhost:7200/', 0, {
    'Accept': RDFMimeType.SPARQL_RESULTS_JSON
});
const server = new ServerClient(serverConfig);
const readTimeout = 30000;
const writeTimeout = 30000;
const repositoryClientConfig = new RepositoryClientConfig(['http://localhost:7200/repositories/testrepo'], {}, '', readTimeout, writeTimeout);

server.getRepository('testrepo',repositoryClientConfig).then(function(repository) {  

    console.log('REPO:', repository);
    repository.registerParser(new SparqlJsonResultParser());

    const payload = new GetQueryPayload()
        .setQuery('select * where {?s ?p ?o}')
        .setQueryType(QueryType.SELECT)
        .setResponseType(RDFMimeType.SPARQL_RESULTS_JSON)
        .setLimit(100);
    return repository.query(payload);

})
.then(function(stream) {
    console.log('SELECT:');
    stream.on('data', function(bindings) {
        var test = Object.values(bindings);
        console.log('DATA');
        // var element = {id: test[0].id.replace(/['"]+/g, ''), name: test[1].id.replace(/['"]+/g, '')}
    });
    stream.on('end', function() {
        console.log('END');
        // restapp.get('/getallIDs', function(req,res)  {
        //     res.send(element);
        // });
        // restapp.listen(3000, function () {
        //     console.log('App listening on port 3000!');
        // });
    });
})
.catch(function(error) {
    console.log('ERROR', error);
});

您可以解决的另一件事是 res.send(element); 调用，正如我所看到的那样，它实际上会发送 undefined，因为 element 的范围在 stream.on('data' 回调中。因此，您可以通过在 stream.on('data' 行之前定义 var element; 来使其可用。

Answer 2

最好的结构化方式是文件分明，一个是主节点app.js

    var express = require('express');
var restapp = express();
var queryController = require('./controllers/queryController')

restapp.use(queryController)

restapp.listen(3001, function () {
    console.log('Αpp listening on port 3001!');
});

并且暗示您导入了 queryController.js，其中包括执行您需要的每个不同查询的代码到 graphdb 服务器

var express = require('express');
var router = express.Router()

const {ServerClient, ServerClientConfig} = require('graphdb').server;
const {RDFMimeType} = require('graphdb').http;
const {RepositoryClientConfig} = require('graphdb').repository;
const {SparqlJsonResultParser} = require('graphdb').parser;
const {GetQueryPayload} = require('graphdb').query;
const {QueryType}= require('graphdb').query;
const serverConfig = new ServerClientConfig('http://localhost:7200', 0, {
    'Accept': RDFMimeType.SPARQL_RESULTS_JSON
});

router.get('/hi', (req, res) => {
      res.send('hi')
})



router.get('/getallids', (req, res) => {
    head = {};
    table = [];
    head.table = table;
    const server = new ServerClient(serverConfig);
    const readTimeout = 30000;
    const writeTimeout = 30000;
    const repositoryClientConfig = new RepositoryClientConfig(['http://localhost:7200/repositories/V2'], {}, '', readTimeout, writeTimeout);
    server.getRepository('V2',repositoryClientConfig).then(repository => {  
        repository.registerParser(new SparqlJsonResultParser());     
        const payload = new GetQueryPayload()
        .setQuery('select * where {?p ?o ?k}')
        .setQueryType(QueryType.SELECT)
        .setResponseType(RDFMimeType.SPARQL_RESULTS_JSON)
        .setLimit(100);
        repository.query(payload).then((stream) => {
                stream.on('data', (bindings) => {
                var test = Object.values(bindings);
                var i=0;
                test.forEach(function(key,value){
                    test2 = Object.values(key);
                    if (i%2==1){
                    return true;}
                    var element = {id: test[0].id.replace(/['"]+/g, ''), name: test[1].id.replace(/['"]+/g, '')}
                    i++;
                    head.table.push(element);
                });       
            });
            stream.on('end', () => {  
                    res.send(head);   
            });       
        }).catch(err => console.log(err));
    });
})


router.get('/getid/:id', (req, res) => {
    const params = req.params;
    head = {};
    table = [];
    head.table = table;
    const server = new ServerClient(serverConfig);
    const readTimeout = 30000;
    const writeTimeout = 30000;
    const repositoryClientConfig = new RepositoryClientConfig(['http://localhost:7200/repositories/V2'], {}, '', readTimeout, writeTimeout);
    server.getRepository('V2',repositoryClientConfig).then(repository => {  
        repository.registerParser(new SparqlJsonResultParser());     
        const payload = new GetQueryPayload()
        .setQuery('select'+Object.values(params)+'where {?p ?o ?k}')
        .setQueryType(QueryType.SELECT)
        .setResponseType(RDFMimeType.SPARQL_RESULTS_JSON)
        .setLimit(100);
        repository.query(payload).then((stream) => {
                stream.on('data', (bindings) => {
                var test = Object.values(bindings);
                var i=0;
                test.forEach(function(key,value){
                    test2 = Object.values(key);
                    if (i%2==1){
                    return true;}
                    var element = {key: test[0].id.replace(/['"]+/g, ''), value: test[1].id.replace(/['"]+/g, '')}
                    i++;
                    head.table.push(element);
                });       
            });
            stream.on('end', () => {
                    res.send(head);  
            });       
        }).catch(err2 => console.log(err2));
    });
})
module.exports = router;

Graphdb.js node.js 一个 server.repository 通过 Rest API 连接多个查询

Graphdb.js node.js one server.repository connection multiple queries through Rest APIs

rdf

repository

payload

node.js

graphdb