/
mongo.js
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/
mongo.js
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/**
* @fileoverview MongoDb adapter to use in this microservice.
*/
import MongoClient from 'mongodb';
/**
* constants for Mongo DB connection. Currently, none of them exposed
* as env variables, but they can be later.
*/
const DB_PARAMS = {
poolSize: 10,
w: 'majority',
wtimeout: 10000,
j: true,
readPreference: 'ReadPreference.SECONDARY_PREFERRED',
autoReconnect: true,
keepAlive: 300,
connectTimeoutMS: 30000,
socketTimeoutMS: 30000
};
/**
* Creates a Mongo DB connection
* @param {string} endpoint - mongodb endpoint
* @return {Promise}
* if success, a mongodb conn object
* if rejected, error
*/
const connect = (endpoint) => {
return new Promise((resolve, reject) => {
MongoClient.connect(endpoint, DB_PARAMS, (err, db) => {
if (err) {
reject(err);
}
else {
resolve(db);
}
});
});
};
/**
* Setup tables schema and constraints in the Db
* @param {object} db - MongoDb connection
*/
const initialSetup = async (db) => {
// incidents collection
await db.createCollection('incidents');
db.collection('incidents').createIndex({ id: 1 }, { unique: true });
db.collection('incidents').createIndex({ created_at: 1 });
db.collection('incidents').createIndex({ type: 1 });
};
/**
* Returns a DAO for a collection in the mongo db
* @param {object} db Mongo db connection
* @param {string} collectionName - collection name in mongo
* @return {object} DAO functions
* find(), count(), insert(), update(), remove()
*/
const getDao = (db, collectionName) => {
const dbCollection = db.collection(collectionName);
/**
* Find records in a collection
* @param {object} pred - Predicate for find
* @param {object} sort - Sort opiton
* @return {Promise} promise
* on success - array of records
* on failure - Db error
*/
const find = (pred, sort) => {
return new Promise((resolve, reject) => {
dbCollection.find(pred).sort(sort).toArray((err, res) => {
if (err) {
reject(err);
}
else {
resolve(res);
}
});
});
};
/**
* Count records in a collection
* @param {object} pred - Predicate for count
* @return {Promise} promise
* on success - count
* on failure - Db error
*/
const count = (pred = {}) => {
return new Promise((resolve, reject) => {
dbCollection.count(pred, (err, cnt) => {
if (err) {
reject(err);
}
else {
resolve(cnt);
}
});
});
};
/**
* Insert a single record in a collection
* @param {object} data - Data to insert
* @return {Promise} promise
* on success - inserted record
* on failure - Db error
*/
const insert = (data) => {
// making a copy, b/c the save is modifying the original object
const d = Object.assign({}, data);
return new Promise((resolve, reject) => {
dbCollection.insert(d, (err, res) => {
if (err) {
reject(err);
}
else {
resolve(res.ops[0]);
}
});
});
};
/**
* Update a record in a collection
* @param {object} data - Data to be set on the record
* @param {object} pred - Predicate to find record to update
* @return {Promise} promise
* on success - update result
* on failure - Db error
*/
const update = (data, pred) => {
// making a copy, b/c the save is modifying the original object
const d = Object.assign({}, data);
return new Promise((resolve, reject) => {
dbCollection.update(pred, d, { fullResult: true }, (err, res) => {
if (err) {
reject(err);
}
else {
resolve(res.result.nModified);
}
});
});
};
/**
* Delete record(s) from a collection
* @param {object} pred - Predicate to find records to delete
* @return {Promise} promise
* on success - # of records deleted
* on failure - Db error
*/
const remove = (pred = {}) => {
return new Promise((resolve, reject) => {
dbCollection.deleteMany(pred, (err, res) => {
if (err) {
reject(err);
}
else {
resolve(res.deletedCount);
}
});
});
};
return Object.create({
name: collectionName,
insert,
update,
count,
find,
remove
});
};
/**
* Initializes a new Mongo db object. This returns a wrapper over the
* Mongo db connection exposing whatever functionality is needed.
* @param {string} endpoint - mongo db endpoint
* @return {Promise}
* if successful, db wrapper object
* setup()
* dao()
* if rejected, error
*/
const init = async (endpoint) => {
const connection = await connect(endpoint);
let closed = false;
// on close
connection.on('close', () => {
closed = true;
});
// timeout
connection.on('timeout', () => {
closed = true;
});
const db = {
isActive() {
return closed === false;
},
setup() {
return initialSetup(connection);
},
dao(collectionName) {
return getDao(connection, collectionName);
},
dbConn() {
return connection;
}
};
return db;
};
export default { init };