通过Node.js从MongoDB数据库中查询项目时，Android中的Retrofit 2导致Java.io.EOFException

Question

I have been having trouble trying to query multiple MongoDB documents in form of an JSONArray from mLab at once using Retrofit 2 in an Android project. The documents I'm trying to query have the have the same value in one of their fields, so I used the db.collection.find() method in my Node.js API. Here is the android app code.

 productSubscription.add(ProductNetworkUtil
     .getProductRetrofit(myToken).getProductByCategory("Hardware")
     .observeOn(AndroidSchedulers.mainThread())
     .subscribeOn(Schedulers.io())
      .subscribe(this::handleProductListResponse,this::handleProductError));

            private void handleProductResponse(Product product)
            {
                String itemName = product.getItemName();
                Snackbar.make(findViewById(R.id.content_home_screen), itemName, Snackbar.LENGTH_LONG).show();
                int stop = 0;
            }
            private void handleProductListResponse(JSONArray productList)
            {
                Snackbar.make(findViewById(R.id.content_home_screen),"Hardware list received",Snackbar.LENGTH_SHORT).show();
                int stop = 0;
            }
            private void handleProductError(Throwable error)
            {
                if(error instanceof HttpException)
                {
                    Gson gson  = new GsonBuilder().create();
                    try
                    {
                        String errorBody = ((HttpException)error).response().errorBody().string();
                        Response response = gson.fromJson(errorBody,Response.class);
                        Snackbar.make(findViewById(R.id.content_home_screen),response.getMessage(),Snackbar.LENGTH_SHORT).show();
                    }
                    catch (IOException e)
                    {
                        e.printStackTrace();
                    }
                }
                else
                {
                    Snackbar.make(findViewById(R.id.content_home_screen),"Network Error!",Snackbar.LENGTH_SHORT).show();
                }
            }

Here is the ProductNetworkUtil class used in the previous snippet,

public class ProductNetworkUtil {
public static Retrofit2ProductInterface getProductRetrofit(String token) {

    OkHttpClient.Builder httpClient = new OkHttpClient.Builder();

    httpClient.addInterceptor(chain -> {

        Request original = chain.request();
        Request.Builder builder = original.newBuilder()
                .addHeader("x-access-token", token)
                .method(original.method(),original.body());
        return  chain.proceed(builder.build());

    });

    RxJavaCallAdapterFactory rxAdapter = RxJavaCallAdapterFactory.createWithScheduler(Schedulers.io());

    return new Retrofit.Builder()
            .baseUrl(NewLoginConstants.PRODUCT_FETCHER_URL)
            .client(httpClient.build())
            .addCallAdapterFactory(rxAdapter)
            .addConverterFactory(GsonConverterFactory.create())
            .build().create(Retrofit2ProductInterface.class);
}}

Here is the Interface class I have been using:

enter cpublic interface Retrofit2ProductInterface {

@GET("products/{itemName}")
Observable<Product> getProduct(@Path("itemName") String itemName);

@GET("products/{category}")
Observable<JSONArray> getProductByCategory(@Header("category") String category);}

If I were to use the query method using the itemName field as the parameter, I can query successfully since inside the database the itemName for each document is unique. However, the getProductByCategory method results in Java.io.EOFException: End of input at line 1 column 1 path $ in the debugger. I have searched for some answers and some say this is due to the app receiving empty data. So I tried to change the node.js code as well.

    exports.getProductByCategory = category => 

    new Promise ((resolve,reject) => {

    var productList = product.find({ category: category }, { 
        _id: 1,
        QRCode: 1,
        owner: 1,
        itemName: 1,
        salePrice: 1,
        price: 1,
        sku: 1,
        webCode: 1,
        summary: 1,
        description: 1,
        inTheBox: 1,
        warranty: 1,
        category: 1,
        mainImg: 1,
        otherImgs: 1
     }).toArray();
     product.resolve({productList, message: 'Got your list!'})
    .catch(err => reject({ status: 500, message: 'Internal Server Error !' }))

});

Here is the related code from the routes.js of the node.js API

'use strict';

const detail = require('./functions/detail'); const config = require('./config/config.json');

module.exports = router => {

router.get('/', (req, res) => res.end('This is the product node!'));

router.get('/products/:id', (req,res) => {
        detail.getProduct(req.params.id)
        .then(result => res.json(result))
        .catch(err => res.status(err.status).json({ message: err.message }));
});

    router.get('/products/:category', (req,res) => {
    detail.getProductByCategory(req.params.category)
    .then(result => res.json(result))
    .catch(err => res.status(err.status).json({message: err.message}));
});

}

I am not sure if the node.js API has some fundamental coding error, or it is the android query method that is the issue.

Answer 1

I cannot say anything because I would need more info and check it by myself (your response data).

Did you try to debug / log and check what is the response content? It looks that it's wrong.