Creating new project with auto-testing feature.
It uses basic express.
The question is how to orginize the code in order to be able to test it properly. (with mocha)
Almost every controller needs to have access to the database in order to fetch some data to proceed. But while testing - reaching the actual database is unwanted.
There are two ways as I see:
Stubbing a function, which intends to read/write from/to database.
Building two separate controller builders, one of each will be used to reach it from the endpoints, another one from tests.
just like that:
let myController = new TargetController(AuthService, DatabaseService...);
myController.targetMethod()
let myTestController = new TargetController(FakeAuthService, FakeDatabaseService...);
myTestController.targetMethod() // This method will use fake services which doesnt have any remote connection functionality
Every property passed will be set to a private variable inside the constructor of the controller. And by aiming to this private variable we could not care about what type of call it is. Test or Production one.
Is that a good approach of should it be remade?
Alright, It's considered to be a good practice as it is actually a dependency injection pattern
Related
I am new to node and typescript. I am working on developing a node library that reaches out to another rest API to get and post data. This library is consumed by a/any UI application to send and receive data from the API service. Now my question is, how do I maintain environment specific configuration within the library? Like for ex:
Consumer calls GET /user
user end point on the consumer side calls a method in the library to get data
But if the consumer is calling the user end point in test environment I want the library to hit the following API Url
for test http://api.test.userinformation.company.com/user
for beta http://api.beta.userinformation.company.com/user
As far as I understand the library is just a reference and is running within the consumer application. Library can for sure get the environment from the consumer, but I do not want the consumer having to specify the full URL that needs to be hit, since that would be the responsibility of the library to figure out.
Note: URL is not the only problem, I can solve that with environment switch within the library, I have some client secrets based on environments which I can neither store in the code nor checkin to source control.
Additional Information
(as per jfriend00's request in comments)
My library has a LibExecutionEngine class and one method in it, which is the entry point of the library:
export class LibExecutionEngine implements ExecutionEngine {
constructor(private environment: Environments, private trailLoader:
TrailLoader) {}
async GetUserInfo(
userId: string,
userGroupVersion: string
): Promise<UserInfo> {
return this.userLoader.loadUserInfo(userId, userGroupVersion)
}
}
export interface ExecutionEngine {
GetUserInfo(userId: string, userGroupVersion: string): Promise<UserInfo>
}
The consumer starts to use the library by creating an instance of the LibraryExecution then calling the getuserinfo for example. As you see the constructor for the class accepts an environment. Once I have the environment in the library, I need to somehow load the values for keys API Url, APIClientId and APIClientSecret from within the constructor. I know of two ways to do this:
Option 1
I could do something like this._configLoader.SetConfigVariables(environment) where configLoader.ts is a class that loads the specific configuration values from files({environment}.json), but this would mean I maintain the above mentioned URL variables and the respective clientid, clientsecret to be able to hit the URL in a json file, which I should not be checking in to source control.
Option 2
I could use dotenv npm package, and create one .env file where I define the three keys, and then the values are stored in the deployment configuration which works perfectly for an independently deployable application, but this is a library and doesn't run by itself in any environment.
Option 3
Accept a configuration object from the consumer, which means that the consumer of the library provides the URL, clientId, and clientSecret based on the environment for the library to access, but why should the responsibility of maintaining the necessary variables for library be put on the consumer?
Please suggest on how best to implement this.
So, I think I got some clarity. Lets call my Library L, and consuming app C1 and the API that the library makes a call out to get user info as A. All are internal applications in our org and have a OAuth setup to be able to communicate, our infosec team provides those clientids and secrets to individual applications, so I think my clarity here is: C1 would request their own clientid and clientsecret to hit A's URL, C1 would then pass in the three config values to the library, which the library uses to communicate with A. Same applies for some C2 in the future.
Which would mean that L somehow needs to accept a full configuration object with all required config values from its consumers C1, C2 etc.
Yes, that sounds like the proper approach. The library is just some code doing what it's told. It's the client in this case that had to fetch the clientid and clientsecret from the infosec team and maintain them and keep them safe and the client also has the URL that goes with them. So, the client passes all this into your library, ideally just once per instance and you then keep it in your instance data for the duration of that instance
As per the title, can a Node.js package require a database connection?
For example, I have written a specific piece of middlware functionality that I plan to publish via NPM, however, it requires a connection to a NoSQL database. The functionality in its current state uses Mongoose to save data in a specific format and returns a boolean value.
Is this considered bad practice?
It is not a bad practice as long as you require the DB needed and also explicitly state it clearly in your Readme.md file, it's only a bad practice when you go ahead and work without provide a comment in your codes or a readme.md file that will guide any other person going through your codes.
Example:
//require your NoSQL database eg MongoDB
const mongoose = require('mongoose');
// to connect to the database. **boy** is the database name
mongoose.connect('mongodb://localhost/boy', function(err) {
if (err) {
console.log(err);
} else {
console.log("Success");
}
});
You generally have two choices when your module needs a database and wants to remain as independently useful as possible:
You can load a preferred database in your code and use it.
You can provide the developer using your module a means of passing in a database that meets your specification to be used by your module. The usual way of passing in the database would be for the developer using your module to pass your module the data in a module constructor function.
In the first case, you may need to allow the developer to specify a disk store path to be used. In the second case, you have to be very specific in your documentation about what kind of database interface is required.
There's also a hybrid option where you offer the developer the option of configuring and passing you a database, but if not provided, then you load your own.
The functionality in its current state uses Mongoose to save data in a specific format and returns a boolean value. Is this considered bad practice?
No, it's not a bad practice. This would be an implementation of option number 1 above. As long as your customers (the developers using your module) don't mind you loading and using Mongoose, then this is perfectly fine.
The project I'm working on uses the feathers JS framework server side. Many of the services have hooks (or middleware) that make other calls and attach data before sending back to the client. If I have a new feature that needs to query a database but for a only few specific things I'm thinking I don't want to use the already built out "find" method for this database query as that "find" method has many other unneeded hooks and calls to other databases to get data I do not need for this new query on my feature.
My two solutions so far:
I could use the standard "find" query and just write if statements in all hooks that check for a specific string parameter that can be passed in on client side so these hooks are deactivated on this specific call but that seems tedious especially if I find this need for several other different services that have already been built out.
I initialize a second service below my main service so if my main service is:
app.use('/comments', new JHService(options));
right underneath I write:
app.use('/comments/allParticipants', new JHService(options));
And then attach a whole new set of hooks for that service. Basically it's a whole new service with the only relation to the origin in that the first part of it's name is 'comments' Since I'm new to feathers I'm not sure if that is a performant or optimal solution.
Is there a better solution then those options? or is option 1 or option 2 the most correct way to solve my current issue?
You can always wrap the population hooks into a conditional hook:
const hooks = require('feathers-hooks-common');
app.service('myservice').after({
create: hooks.iff(hook => hook.params.populate !== false, populateEntries)
});
Now population will only run if params.populate is not false.
I have a few PHP scripts which I am in the process of migrating to Node.js. I am using Sails.js for this and I would like to know how I can change databases for each request based on a request parameter.
Currently I have 3-4 identical PostgreSQL databases. Let's just say that each database corresponds to a different client.
Below is a segment of the current PHP script where the database connection is established:
$database = $_GET['db'];
$conn_details = "host=localhost port=5432 dbname=$database user=****** password=******";
$dbconn = pg_connect($conn_details);
Here you can see that the database name is coming from the request parameter "db".
I would like to have a similar functionality in my sails.js controller. I know that i can declare multiple databases in the connections.js and that I can have models use different databases but what i am after is for the models to stay the same and only the database to change based on each request.
I have found 2 similar questions but they have both stayed unanswered for quite some time now. (Here and here)
I think you are looking for something like sub apps
sails-hook-subapps
but it's experimental module. So i wouldn't recommend using it on production. Other option also not good is multiplying your Models like that:
One main model with all methods, attributes and "stuff"
Many models with connections config
In 'parent' model you will select to which model you want to send send action. For example write method:
getModel: function(dbName){
return models[dbName];
}
in models Object you will store all Models with different connections. Not sure how validators will works in this scenario. You need to test if it will not be required do do something like this in child Models
attributes: parentModel.attributes
I'm building a Repository layer with higher level API for my abstractions above to make calls to the database persistence. But since JavaScript doesn't have the concept of Interfaces like a language such as C# or Java does, how do you swap out the mock for the real implementation?
I prefer creating custom mocks, node repository modules with data persitence high level methods in them vs. Sinon.js or something like that.
If I'm creating node modules, then how? I could send in a mock representation of the repository where I mock out what the repository methods are doing but then the actual node modules using those repository modules would need to use the real repository implementation that calls the real database. How is this done in Node? I want to just inject via a property, I don't want some gigantic injection IoC framework either.
Since there's no concept of an interface then wtf do you do in Node/JS? I have to create a data layer below the repository (whether it be a custom set of modules making real query calls to Postgres or whether I'm using Mongoose or whatever it may be, I need a DL set of modules that the repository calls for tis real DB calls under the hood).
And lets say I do choose to use some framework like Sinon.js, what's the common interface for the module you're mocking that can be shared by the mocking framework and the real module?
There's more than one way to do it. If you come from a different background it may take some getting used to Node.
You can do this:
module.exports = function(db) {
this.db = db;
this.myQuery = function(n, cb) {
this.db.query(n, cb);
}
}
Then in config.js
var exports.db = require('./mydb');
Then
var config = require('./config.js');
var db = require('./db')(config.db);
There are lots of variations possible. You could do a dynamic require somewhere based on a string or something. Or use classes or init functions. Most are going to probably end up being similar.
The proxyrequire module could be helpful. So can Sinon.js.
Since there really isn't type checking people generally are verifying that with their tests at runtime. If you are really doing TDD it might not make a huge difference.