CODEWITHSUNDEEP
loopbackjs
zono
zono

Reputation: 8584

Loopback.js How to use connector-rest?

I'm trying to make an example app with connector-rest.

https://github.com/strongloop/loopback-connector-rest

My goal is making the following api.

$ curl http://localhost:3001/addresses/17F54d4S9aLpvUEsk7MkYWafmzxJhhb9wW/balance
{
  "balance": 42030
}

The balance is retrieved from blockchain.info api.

$ curl https://blockchain.info/balance?active=17F54d4S9aLpvUEsk7MkYWafmzxJhhb9wW
{"17F54d4S9aLpvUEsk7MkYWafmzxJhhb9wW": {
    "final_balance": 42030,
    "n_tx": 2,
    "total_received": 42030
}}

The followings are what I've done.

  1. Create Loopback app
  2. Create Rest datasource
  3. Create Address model

But I don't know what should I do next? I think I need to configure something for request. Should I add it into datasources.json? How to call it from addresses.js?

My code is saved on github. https://github.com/y-zono/loopback-connector-rest-example

Update 1

I found this example.

https://github.com/strongloop-community/loopback-example-connector/tree/rest

Then, I could fetch data from blockchain.info.

https://github.com/y-zono/loopback-connector-rest-example/commit/f5e8f96a666f4fdab5d554e657f630635237c2c1

Still not sure whether this is normal way or not. I'm checking about that.

Upvotes: 0

Views: 529

Answers (1)

zono
zono

Reputation: 8584

I found it and I confirmed Promise and async/await work well.

Any suggestions are welcome and appreciated when you have any other better ways.

*address.js

'use strict';

module.exports = function (Address) {

    async function getBalanceFromBlockchainInfo(address) {
        const blockchaininfo = Address.app.dataSources.blockchaininfo;
        try {
            const data = await Promise.all([
                blockchaininfo.balance(address),
                blockchaininfo.balance(address)
            ])
            return { "balance": data[0][address]["final_balance"], "unconfirmed_balance": data[0][address]["final_balance"] };
        } catch (err) {
            return err;
        }
    }

    Address.getBalance = function (address, callback) {
        getBalanceFromBlockchainInfo(address).then(data => callback(null, data)).catch(err => callback(err));
    };

    Address.remoteMethod("getBalance", {
        http: { verb: "get", path: "/:address/balances" },
        accepts: [
            { arg: "address", type: "string", required: true }
        ],
        returns: { type: "object", root: true }
    });
};

*datasources.json

{
  "db": {
    "name": "db",
    "connector": "memory"
  },
  "blockchaininfo": {
    "name": "blockchaininfo",
    "connector": "rest",
    "operations": [
      {
        "template": {
          "method": "GET",
          "url": "https://blockchain.info/balance",
          "query": {
            "active": "{address}"
          }
        },
        "functions": {
          "balance": [
            "address"
          ]
        }
      }
    ]
  }
}

https://github.com/y-zono/loopback-connector-rest-example

Upvotes: 1

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