Lesson 15 moralis server alternatives for Centralized DataBase

[AGMASO]

Hi Guys!

My name is Alejandro G. I´m currently in the Lesson 15 and a bit discourage. I have tried to host myself the Moralis server following the instructions, but after all, i found out is not possible to connect the Moralis Server/streams to the hardhat local node and to listen to events.

I have tried also to create a Stream to listen to the events of the NFTmarketPlace contract deployed to GOerli Blockchain, but somehow also not successful.

I will try to follow the Lesson and continue with the Decentralize option , which is TheGraph, but:

1- Are there other alternatives to listen to the blockchain and add the events triggered to a database (for example MongoDB), the same way as Moralis?

2- I would like to learn a Centralized way to listen to events or other info from the blockchain.

I will appreciate if someone could bring a bit of light about this theme. I'm a bit lost/confused.

Thank you so much to all of you!!

[alymurtazamemon]

@AGMASO Yes, ethers has its own functions for listening for events and Patrick had used those many times in the course. Like contractInstance.on or contractInstance.once, etc, you can find those in the docs.

Patrick also used those while testing the events in lesson 9 and others.

[EricTES]

Would it slow down to website if we use contractInstance.once ? Since it's constantly listening to the blockchain right?

[alymurtazamemon]

@AGMASO I never check the website speed by using it. But this is the way for listening to events on the frontend side provided by the ethers.js library.

[AGMASO]

Hi @alymurtazamemon Thank you so much for your answer.

After I wrote this message, I reviewed the older lesson and I saw that we used those functions of ethers to listen to events.

But still have few questions about the centralized server strategie:

1- Why is he using Moralis to listen to the events and to store the data if we could use Ethers functions such as contractInstance.on to listen to the smart contract's events and then create a server with express to finally store the data in MongoDB? I guess it is because before the moralis´s update, it was easier and faster to use the server of Moralis. Is that right?

2- I have followed the instructions to set a self-host moralis server and I used the Streams of Moralis to listen to the events of the contract and store the data in MongoDB.

My question is: Can I follow now the tutorial of Patrick? I see he uses some moralis's functions (for example useMoralisQuery()) to index the data of the events to our index.js.

Having the data stored in MongoDb, will this work? Or should I create some GET method on the server-side (in this case the self-hosted Moralis-server) to fetch the data?

Thank you so much
Greetings,
Alejandro

[0fprod]

Hi Alejandro, I just reached this same situation. Moralis is not providing servers anymore, how did you solve it? Did you have to create your own backend server and listen to events 'natively? Is it possible to config and listen the Moralis.Streams and then somehow store the data in you own db?

Thanks

[AGMASO]

@franjpr Hola Fran!

Te lo escribo en inglés por si le sirve a alguien de ayuda.

First, I followed the guide to install the Moralis-Parse-Server in my computer. This worked well, and I ended listening the events of the blockchain and adding to my MongoDb data base. The problem is that, moralis is not anymore a free of charge service.
So, you can only create one Stream to listen just one event.
Now I decided to build my own NextJs app, and listen the events of the chain using Ethers. After it, creating in the serverside the POST method to add the data to MongoDB. After it, just call with GET method to add the Nfts data to our index.js.

I hope I helped you.

Un saludo!!

[0fprod]

@AGMASO Gracias!

Perfect mate! it makes sense 😄

[digitalhumanlife]

Have you got it to work? @AGMASO

[silent7-x]

Hello @AGMASO,

congrats for your hardwork.

I'm not that fluent with express, would you mind sharing a gh repo with your code for frontend and backend using express?

Thanks