RxAndroid onNext being called multiple times - retrofit2

Question

I am calling an api via retrofit with RxAndroid. Here's how the method is defined
#GET("product")
Observable<BaseResponse<List<Product>>> getProducts(#Query("lang") String lang,
#Query("category_id") String category_id,
#Query("start") String start,
#Query("count") String count);
This api returns the list of Product. I wanted to process each Product object inside list to check if that product exists in local db & set the boolean in product object. So I did it like this,
public Observable<List<Product>> getProductList(String catId, int start, int count) {
final List<Product> products = new ArrayList<>();
return RestClient.callApiWrapper(mContext, true, null,
RestClient.get().getProducts("en", catId, "" + start, "" + count))
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.flatMapIterable(new Func1<BaseResponse<List<Product>>, Iterable<Product>>() {
#Override
public Iterable<Product> call(BaseResponse<List<Product>> listBaseResponse) {
Log.e("TAG", "flatMapIterable called");
return listBaseResponse.getData();
}
})
.map(new Func1<Product, List<Product>>() {
#Override
public List<Product> call(Product product) {
Log.e("TAG", "map called => " + products.size());
products.add(checkIfProductAddedToCart(product));
return products;
}
});
}
I have subscribed to getProductList where I need the processed list in this way:
mProductListDataModel.getProductList(mCategoryId, mStartOffset, mCount)
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<List<Product>>() {
#Override
public void onCompleted() {
}
#Override
public void onError(Throwable e) {
}
#Override
public void onNext(List<Product> products) {
Log.e("TAG", "onNext => " + products.size());
if(mOnProductListLoaded != null)
mOnProductListLoaded.onProductListLoaded(products);
}
});
Now the problem is, the API actually returns list of 5 products, but onNext is being called 5 times each time with increasing size upto 40 products. Please let me know where I am doing wrong.

Answer 1

I have changed few things for now, which are as below which works for me:
changed getProductList to return Product instead of List<Product>
so it looks like
public Observable<Product> getProductList(String catId, int start, int count) {
//final List<Product> products = new ArrayList<>();
return RestClient.callApiWrapper(mContext, true, null,
RestClient.get().getProducts("en", catId, "" + start, "" + count))
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.flatMap(new Func1<BaseResponse<List<Product>>, Observable<Product>>() {
#Override
public Observable<Product> call(BaseResponse<List<Product>> listBaseResponse) {
return Observable.from(listBaseResponse.getData());
}
})
.map(new Func1<Product, Product>() {
#Override
public Product call(Product product) {
//Log.e("TAG", "map called => " + products.size());
//products.add(checkIfProductAddedToCart(product));
//return products;
return checkIfProductAddedToCart(product);
}
});
}
and changed following where this observable was subscribed:
final List<Product> products = new ArrayList<>();
mProductListDataModel.getProductList(mCategoryId, mStartOffset, mCount)
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<Product>() {
#Override
public void onCompleted() {
Log.e("TAG", "onCompleted => " + products.size());
if (mOnProductListLoaded != null)
mOnProductListLoaded.onProductListLoaded(products);
}
#Override
public void onError(Throwable e) {
}
#Override
public void onNext(Product product) {
products.add(product);
}
});
However, I am still not sure if this is the right way of doing this. Please let me know if this is not the right way to do so.