I use yapps to generate a parser for a LaTex-ish language (for example to translate stuff like \begin{itemize} to the corresponding <ul>-Tags) within pyramid. One command (i.e. \ref{SOMEID}) should construct a route via a call of route_url (or route_path) and pass the id to it. Since this call happens deep in the code that was generated by yapps and the grammar that I defined, I don't see any possibility to pass a request object to it.
Is there some sort of global request object? Or, since I foresee that I shouldn't use it, is there a possibility to construct a route (that depends on a parameter) without a request object?
route_url requires both a request and a registry (request.registry). It generates urls relative to the request, and it accesses the list of all routes and other settings from the registry. Thus, you must generate a dummy request with parameters you care about. For example:
from pyramid.request import Request
request = Request.blank('/', base_url='https://example.com/prefix')
request.registry = config.registry
Now you can store this request anywhere, it's good to go representing everything about your site: the hostname/port (example.com:443), the prefix your app is mounted at (/prefix), the uri scheme (https).
If you need to get this deep down into your code you may have to make it a global or attach it to some context/registry that you have available, but what I've shown is how to make the request that you require.
Related
I created a router file using Express. The callback functions reside in their discrete "controllers" files. Following is an excerpt of the parts relevant to my question, and lines such as require of controller functions have been omitted:
const express = require('express');
const router = express.Router();
// This should run first
router.param('coolParamName', validateParamBeforeHandlingReqs);
// Param name is ↑↑↑↑↑ "consumed" here, although NOT defined yet
// This should run after the above code
router.route('/').get(getAllUserNames).post(createUser);
router.route('/:coolParamName').get(getUserName).patch(updateUser).delete(deleteUser);
// Param name is ↑↑↑↑↑ defined here, and was consumed earlier - how?
As the comments explain, it seems like the param name has been defined as coolParamName on the bottom, but "consumed" by the code written above it. This feels strange to me, because I feel it's natural to define first and then use later - is it just me? Did I write a code that's against the intended design pattern?
I would like to understand how Express defines the name of param, and how router.param and router.router handle them.
router.param('coolParamName') essentially registers a callback that will get called for any route (in that router) that uses the :coolParamName parameter and matches the current request. The callback will get called once per request BEFORE the route that matches the request that contains the :coolParamName parameter.
It's kind of like middleware for a matching parameter. It allows you to automatically configure some setup code anytime that particular parameter is matched in a route.
FYI, I expect that router.param() may be one of the least used features of Express since it can be accomplished many other ways, but it probably works best for validation-type code that checks named properties for validity before the route itself gets called.
You could accomplish the same thing by just using a piece of middleware on that specific route too or even just calling a function inside the route handler. So, this is just a nicety feature if you happen to use the same parameter in multiple routes.
I am using NestJS (version 6.5, with Express platform) and I need to handle a request with a property that can either be a File or a String.
Here is the code I currently have, but I don't find a clean way to implement this.
MyAwesomeController
#Post()
#UseInterceptors(FileInterceptor('source'))
async handle(#UploadedFile() source, #Body() myDto: MyDto): Promise<any> {
//do things...
}
Am I missing something obvious or am I supposed to write my own interceptor to handle this case?
Design-wise, is this bad?
Based on the fact you're designing a REST API:
It depends what use case(s) you want to achieve: is your - client-side - flow designed to be performed in 2 steps o not ?
Can string and file params be both passed at the same time or is there only one of the two on each call ? (like if you want to update a file and its name, or some other non Multer related attributes).
When you pass a string as parameter to your endpoint call, is a file resource created / updated / deleted ? Or maybe not at all ?
Depending on the answer and the flow that you thought of, you should split both cases handling within two independent endpoints, or maybe it makes sense to handle both parameters at the same time.
If only one of the params can be passed at a time, I'd say go for two independent endpoints; you'll benefit from both maintenance and code readability.
If both params can be passed at the same time and they're related to the same resource, then it could make sense to handle both of them at once.
Hope this helps, don't hesitate to comment ;)
I am new to Node.js, and I have been reading questions and answers related with this issue, but still not very sure if I fully understand the concept in my case.
Suggested Code
router.post('/test123', function(req, res) {
someAsyncFunction1(parameter1, function(result1) {
someAsyncFunction2(parameter2, function(result2) {
someAsyncFunction3(parameter3, function(result3) {
var theVariable1 = req.body.something1;
var theVariable2 = req.body.something2;
)}
)}
});
Question
I assume there will be multiple (can be 10+, 100+, or whatever) requests to one certain place (for example, ajax request to /test123, as shown above) at the same time with some variables (something1 and something2). According to this, it would be impossible that one user's theVariable1 and theVariable2 are mixed up with (i.e, overwritten by) the other user's req.body.something1 and req.body.something2. I am wondering if this is true when there are multiple callbacks (three like the above, or ten, just in case).
And, I also consider using res.locals to save some data from callbacks (instead of using theVariable1 and theVariable2, but is it good idea to do so given that the data will not be overwritten due to multiple simultaneous requests from clients?
Each request an Node.js/Express server gets generated a new req object.
So in the line router.post('/test123', function(req, res), the req object that's being passed in as an argument is unique to that HTTP connection.
You don't have to worry about multiple functions or callbacks. In a traditional application, if I have two objects cat and dog that I can pass to the listen function, I would get back meow and bark. Even though there's only one listen function. That's sort of how you can view an Express app. Even though you have all these get and post functions, every user's request is passed to them as a unique entity.
How can I remove the Server HTTP response header in Yesod? I found code that's responsible for setting that header, but I don't know what to do next. I know that I can replace the header value with an empty string by using addHeader "Server" "", but I'd prefer to remove it entirely.
I made an issue on GitHub Warp repository and they changed it that when the server name is empty, the "Server" header is not sent. Therefore, the solution is to set the server name to an empty string using setServerName "". In my case I had to add this to the warpSettings function in Application.hs. Note that you have to use the Warp version which contains the fix (as of May 3 '17, it has not been released yet, but you can pull it directly from GitHub).
You must call the methods inside of the function you linked. That function will "The Date and Server header is added if not exist in HTTP response header" so you need to reimplement it if you don't want that behavior.
This is why people always say to keep your code modular and your functions small; this function is too big for your use case, and there is no specific smaller function that does exactly what you want (or else it would have been called by this function!)
This is an extension of this question.
In my models, every one requires a companyId to be set on creation and every one requires models to be filtered by the same session held companyid.
With sails.js, I have read and understand that session is not available in the model unless I inject it using the controller, however this would require me to code all my controller/actions with something very, very repetitive. Unfortunate.
I like sails.js and want to make the switch, but can anyone describe to me a better way? I'm hoping I have just missed something.
So, if I understand you correctly, you want to avoid lots of code like this in your controllers:
SomeModel.create({companyId: req.session.companyId, ...})
SomeModel.find({companyId: req.session.companyId, ...})
Fair enough. Maybe you're concerned that companyId will be renamed in the future, or need to be further processed. The simplest solution if you're using custom controller actions would be to make class methods for your models that accept the request as an argument:
SomeModel.doCreate(req, ...);
SomeModel.doFind(req, ...);
On the other hand, if you're on v0.10.x and you can use blueprints for some CRUD actions, you will benefit from the ability to override the blueprints with your own code, so that all of your creates and finds automatically use the companyId from the session.
If you're coming from a non-Node background, this might all induce some head-scratching. "Why can't you just make the session available everywhere?" you might ask. "LIKE THEY DO IN PHP!"
The reason is that PHP is stateless--every request that comes in gets essentially a fresh copy of the app, with nothing in memory being shared between requests. This means that any global variables will be valid for the life of a single request only. That wonderful $_SESSION hash is yours and yours alone, and once the request is processed, it disappears.
Contrast this with Node apps, which essentially run in a single process. Any global variables you set would be shared between every request that comes in, and since requests are handled asynchronously, there's no guarantee that one request will finish before another starts. So a scenario like this could easily occur:
Request A comes in.
Sails acquires the session for Request A and stores it in the global $_SESSION object.
Request A calls SomeModel.find(), which calls out to a database asynchronously
While the database does its magic, Request A surrenders its control of the Node thread
Request B comes in.
Sails acquires the session for Request B and stores it in the global $_SESSION object.
Request B surrenders its control of the thread to do some other asynchronous call.
Request A comes back with the result of its database call, and reads something from the $_SESSION object.
You can see the issue here--Request A now has the wrong session data. This is the reason why the session object lives inside the request object, and why it needs to be passed around to any code that wants to use it. Trying too hard to circumvent this will inevitably lead to trouble.
Best option I can think of is to take advantage of JS, and make some globally accessible functions.
But its gonna have a code smell :(
I prefer to make a policy that add the companyId inside the body.param like this:
// Needs to be Logged
module.exports = function(req, res, next) {
sails.log.verbose('[Policy.insertCompanyId() called] ' + __filename);
if (req.session) {
req.body.user = req.session.companyId;
//or something like AuthService.getCompanyId(req.session);
return next();
}
var err = 'Missing companyId';
//log ...
return res.redirect(307, '/');
};