Main differences between req.query and req.param in Express
How are Both different from each other
When to use then in what cases
Suppose a client sends say Android (Key,value) pair in the request ........ which one to use ?
[EDIT]
Suppose android sends a POST request -> Intention is to send (Key,Value) to client and the server should perform a database query based on the value in the server and return JSON response
Look:: at this question for the program i referenced:: Simple Express program for querying a result
req.query will return a JS object after the query string is parsed.
/user?name=tom&age=55 - req.query would yield {name:"tom", age: "55"}
req.params will return parameters in the matched route.
If your route is /user/:id and you make a request to /user/5 - req.params would yield {id: "5"}
req.param is a function that peels parameters out of the request. All of this can be found here.
UPDATE
If the verb is a POST and you are using bodyParser, then you should be able to get the form body in you function with req.body. That will be the parsed JS version of the POSTed form.
req.query is the query string sent to the server, example /page?test=1, req.param is the parameters passed to the handler.
app.get('/user/:id', handler);, going to /user/blah, req.param.id would return blah;
I would suggest using following
req.param('<param_name>')
req.param("") works as following
Lookup is performed in the following order:
req.params
req.body
req.query
Direct access to req.body, req.params, and req.query should be favoured for clarity - unless you truly accept input from each object.
Ref:http://expressjs.com/4x/api.html#req.param
Passing params
GET request to "/cars/honda"
returns a list of Honda car models
Passing query
GET request to "/car/honda?color=blue"
returns a list of Honda car models,
but filtered so only models with an stock color of blue are returned.
It doesn't make sense to add those filters into the URL parameters (/car/honda/color/blue) because according to REST, that would imply that we want to get a bunch of information about the color "blue". Since what we really want is a filtered list of Honda models, we use query strings to filter down the results that get returned.
Notice that the query strings are really just { key: value } pairs in a slightly different format: ?key1=value1&key2=value2&key3=value3.
Related
To avoid making multiple http calls from an Angular app, if I want to make one call and send multiple id strings to a node js back-end for deletion, should I be sending them as JSON?
If anyone can point me to a good example that would be great.
thanks
You also try with pass the array of ids in the request.
Example :
var idArray = [1,2,3,4,5,6];
$http(
method: 'DELETE',
url: '/items',
params: {
id: JSON.stringify(idArray)
}
)
You can just send the ID's in a JSON Format as shown below
id:"1000,1001,1002"
and in NodeJS if you are using MYSQL the following query works for delete
let ids = req.body.id;//To get the id sent in JSON Format
delete from table_name where id in (ids)
Comment below if u need any further guidance
I'm looking to extract User email via his id, with findById(), without making another call.
Route method is irrelevant at this point.
router.delete('/:userId', (req,res,next) =>{
console.log(User.findById(req.params.userId).Schema.email);
})
The code above is not working, yet just wanted to put it up to show what i'm trying to extract.
Instead of parsing the User object, does mongoose have a method to extract model attributes via findById() without an async call ? it only makes sense since:
console.log(User.findById(req.params.userId)); does return the whole Mongoose object / Model.
Would be happy to get your thoughts.
Suppose I have a REST endpoint like this :
http://server/users/query
And I have parameters in my query : age, city, country
I want to do a GET request with those parameters.
Should I better pass the parameters in the url ? Or put something like this in the payload of my GET request.
"query": {
"age": "something",
"city": "something",
"country": "something"
}
On my understanding, you have a collection of users and you want to get a representation of it. You should consider query parameters to filter your collection, as following:
http://[host]/api/users?age=something&city=something&country=something
And avoid GET requests with a payload. See the quote from the RFC 7231:
A payload within a GET request message has no defined semantics;
sending a payload body on a GET request might cause some existing
implementations to reject the request.
From MDN: GET requests (typically) don't have bodies so use the query parameters or the path.
If you are making requests to a server you should instead read the documentation of it's API.
Here is below my code of route:-
app.get('/server/lead/get/:id?', leadCtrl.get);
app.get('/server/lead/filter/:filterQuery', leadCtrl.get);
As you see above i am using different route to access same controller method leadCtrl.get.
Now, i want something like route app.get('/server/lead/get/:id?:filter?', leadCtrl.get);. So, i can get params either req.params.id or req.params.filter but only one at a time.
What you asked in the question is not possible in the form that you describe it.
Now, i want something like route
app.get('/server/lead/get/:id?:filter?', leadCtrl.get);. So, i can get
params either req.params.id or req.params.filter but only one at a
time.
Your router would have no way to differentiate those two parameters. If it got a request to /server/lead/get/X then what is X? A filter or an ID?
Your options
You have few solutions here:
You can either keep using two routes like you did before.
You can use a common parameter for both cases as Robert explained in the comments.
Or you can use what seems to me the perfect solution for your use case - named query parameters - just use a route /server/lead/get and use query parameters to pass id and the filter.
Example URLs:
/server/lead/get?id=xxx
/server/lead/get?filterQuery=xxx
You will only have to make sure in your handler that only one of those two are set at a time with something like:
if (req.query.id && req.query.filterQuery) {
// respond with error
}
You can even mix the two if you have app.get('/server/lead/get/:id?') route you can have the id in the route and filterQuery as a query parameter. Now the URLs would be:
/server/lead/get/xxx (for id)
/server/lead/get?filterQuery=xxx (for filter)
For more info see: http://expressjs.com/en/api.html#req.query
Better way
If you follow some REST conventions then you can use:
app.get('/server/lead/:id') for one object with id (not optional)
app.get('/server/lead') for a list of objects (with optional filterQuery passed as a query parameter)
That way you would always know that when you access:
/server/lead/xxx - then it's one object with ID = xxx
/server/lead - then it's a list of any objects
/server/lead?filterQuery=xxx - then it's a list of objects that match the query
If you follow the REST conventions for things like this instead of inventing your own, it would be much easier for you to design the routes and handlers, and it would be much easier for other people to use your system.
You may also want to use plural /server/leads instead of /server/lead which is common with REST. That way it will be more obvious that leads is a list and leads/id is one of its elements.
For more info see:
https://en.wikipedia.org/wiki/Representational_state_transfer
http://www.restapitutorial.com/lessons/whatisrest.html
https://spring.io/understanding/REST
You have to realize that the following two routes match exactly the same:
app.get('/server/lead/get/:id?', leadCtrl.get);
app.get('/server/lead/get/:filter?', leadCtrl.get);
Express doesn't care about how you name the placeholders, so any requests for /server/lead/get/SOMEVALUE will always match the first (the one with :id).
You can add a distinction yourself, by only allowing a parameter to match a particular regular expression. From your code, it looks like :id should match MongoDB ObjectId's, so you can create a specific match for those:
app.get('/server/lead/get/:id([a-fA-F0-9]{24})?', leadCtrl.get);
If SOMEVALUE matches an ObjectId, it will call leadCtrl.get and populate req.params.id. If you also add another router for "the rest", you can also cover the req.params.filter case:
app.get('/server/lead/get/:filter?', leadCtrl.get);
As an aside: you're saying that you're passing JSON to the "filter" routes, in the URL. I would strongly suggest using a POST route for that, and post the JSON as request body content.
I'm writing a REST api in node js that will execute a sql query and send the results;
in the request I need to send the WHERE conditions; ex:
GET 127.0.0.1:5007/users //gets the list of users
GET 127.0.0.1:5007/users
id = 1 //gets the user with id 1
Right now the conditions are passed from the client to the rest api in the request's headers.
In the API I'm using sequelize, an ORM that needs to receive WHERE conditions in a particular form (an object); ex: having the condition:
(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)
this needs to be formatted as a nested object:
-- x=1
-- AND -| -- y=2
| -- OR ----|
| -- z=3
-- OR -|
|
| -- x=3
-- AND -|
-- y=1
so the object would be:
Sequelize.or (
Sequelize.and (
{x=1},
Sequelize.or(
{y=2},
{z=3}
)
),
Sequelize.and (
{x=3},
{y=1}
)
)
Now I'm trying to pass a simple string (like "(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)"), but then I will need a function on the server that can convert the string in the needed object (this method in my opinion has the advantage that the developer writing the client, can pass the where conditions in a simple way, like using sql, and this method is also indipendent from the used ORM, with no need to change the client if we need to change the server or use a different ORM);
The function to read and convert the conditions' string into an object is giving me headache (I'm trying to write one without success, so if you have some examples about how to do something like this...)
What I would like to get is a route capable of executing almost any kind of sql query and give the results:
now I have a different route for everything:
127.0.0.1:5007/users //to get all users
127.0.0.1:5007/users/1 //to get a single user
127.0.0.1:5007/lastusers //to get user registered in the last month
and so on for the other tables i need to query (one route for every kind of request I need in the client);
instead I would like to have only one route, something like:
127.0.0.1:5007/request
(when calling this route I will pass the table name and the conditions' string)
Do you think this solution would be a good solution or you generally use other ways to handle this kind of things?
Do you have any idea on how to write a function to convert the conditions' string into the desired object?
Any suggestion would be appreciated ;)
I would strongly advise you not to expose any part of your database model to your clients. Doing so means you can't change anything you expose without the risk of breaking the clients. One suggestion as far as what you've supplied is that you can and should use query parameters to cut down on the number of endpoints you've got.
GET /users //to get all users
GET /users?registeredInPastDays=30 //to get user registered in the last month
GET /users/1 //to get a single user
Obviously "registeredInPastDays" should be renamed to something less clumsy .. it's just an example.
As far as the conditions string, there ought to be plenty of parsers available online. The grammar looks very straightforward.
IMHO the main disadvantage of your solution is that you are creating just another API for quering data. Why create sthm from scratch if it is already created? You should use existing mature query API and focus on your business logic rather then inventing sthm new.
For example, you can take query syntax from Odata. Many people have been developing that standard for a long time. They have already considered different use cases and obstacles for query API.
Resources are located with a URI. You can use or mix three ways to address them:
Hierarchically with a sequence of path segments:
/users/john/posts/4711
Non hierarchically with query parameters:
/users/john/posts?minVotes=10&minViews=1000&tags=java
With matrix parameters which affect only one path segment:
/users;country=ukraine/posts
This is normally sufficient enough but it has limitations like the maximum length. In your case a problem is that you can't easily describe and and or conjunctions with query parameters. But you can use a custom or standard query syntax. For instance if you want to find all cars or vehicles from Ford except the Capri with a price between $10000 and $20000 Google uses the search parameter
q=cars+OR+vehicles+%22ford%22+-capri+%2410000..%2420000
(the %22 is a escaped ", the %24 a escaped $).
If this does not work for your case and you want to pass data outside of the URI the format is just a matter of your taste. Adding a custom header like X-Filter may be a valid approach. I would tend to use a POST. Although you just want to query data this is still RESTful if you treat your request as the creation of a search result resource:
POST /search HTTP/1.1
your query-data
Your server should return the newly created resource in the Location header:
HTTP/1.1 201 Created
Location: /search/3
The result can still be cached and you can bookmark it or send the link. The downside is that you need an additional POST.