I have a dropdown list which is being used on several pages including the Home page. And I don't want to send data requests to the server for that drop-down list for all those pages. I want that drop-down list to be stored somewhere for all the pages at the time of loading the home page.
I could then use that several times on several pages without sending requests to the server each time. So that I could make my site a bit faster. Is there any way to do this?
You can make use of Singleton Service, which can be referred by all the components in your application. Give the server request to fetch data at the start of application, and store the result in the form of properties or attributes declared within the Singleton Service.
Once you have the data within service, you can simply refer that instead of giving server request every time.
Refer here for Singleton Service : How do I create a singleton service in Angular 2?
Related
My name is Alex.
Sorry for my rather bad Englisch because i come from Germany.
I just started programming with Node.js.
Previously i made some small static HTML and CSS websites.
I have some beginner questions (which might be dump).
I think these questions are very general for now and have therefore not included any code examples.
So far I have written a static HTML website which I host locally on my computer using Node.js and Express.
My Questions are:
Which actions within a web application should take place on the client side and which on the server side. For example, I have several buttons on the start page. With the help of which predefined users can log in. When clicking on a button, the user should be redirected to the login page. The user name of the respective user should be entered directly into the username field on the login page.
How do I implement such a transition?
The username would probably have to be passed to the server using a post call. How does the user get to the next page? Should this be a simple link or should I send the new HTML document to the user via app.sendFile()?
For example, how do I change tags in an HTML document using Node.js. The same example as before a user is logged in and redirected to the next page. Now he should be greeted with his name. The name can be read from a database using the UUID.
How do I get this name into a tag?
Do I need a template engine or are there other ways to change a static HTML page.
Thank you in advance for your help.
In my opinion, security-critical parts logic be placed on the server (logging in, checking balance, authorization, etc.).
Traditionally, no code on the client side is required. You click a link/submit a form, which sends a request to a server, the server responds, the client displays the new page.
Using client side code, however, can make your app smoother and reduce the load of the server. For example: the user clicks on the shopping cart button. Instead of reloading the whole page, the user sends an ajax request, and the server responds with the cart data. Then the client updates the document, displaying the formatted cart data.
You can't "change html tags" from nodejs. You can send a response. If you send a html response, you decide how to produce the response. You can just concatenate html strings, but using a template engine is a better solution.
I've searched and I can only find tutorials to pull info from a server to update the latest info of my PWA app using JSON. But I can't find any way and any example to fetch data back to a server to mantain for instance a Database updated and display that to all users which may use that PWA.
For example, I have a PWA that let me login (client-server communication), then it displays a list of contacts that were stored in a Database. I can delete, modify or add new users to this list from my PWA app, and after doing that, they'll update on my server Database, so if my friend Paul, wants to check the updated list from his account, he'll see the new changes.
How Can I do that? Which language would I have to use, php and Javascript (Ajax)? Which is the most fluid and optimized way to do it according to a Progressive Web App.
I guess you are trying to store user changes back to the server(webservice and then to the data base).
You have to make an AJAX call to your web service and pass the required data needed to store in DB.
Here is an example.
https://www.w3schools.com/xml/xml_http.asp
Depending on the framework you are using, you might have more options to call a web service. Like here is an example for Angular -> https://www.w3schools.com/angular/angular_http.asp
Does Google Data Studio Community connector support pagination?
I work with an external data service. The service returns data page by page. It requires start and next parameters and it requires 2 req/sec. Can I override a method like getData or upgrade request argument for implement this feature?
If it's not. Is there the best practice for getting data of this kind?
Community Connectors do not support pagination for web APIs at present.
The best practice would depend on your use case. If you want to get the full dataset for user, you can make multiple UrlFetch calls to get the full dataset, merge it, and return the merged set as the getdata() response. It might also make sense to cache this result to avoid making a large number of requests in the short term. You can cache using Apps Script cache, or a Sheet, or even to BigQuery. Keep in mind that Apps Script has 6 min / execution limit.
However, if you want to return only specific pages, the only way to configure that would be through getConfig since configparams are passed with the getData() request. Example use case would be returning only first n number of pages where n selected by user in the config.
I am trying to implement an HTML page that displays embedded reports with IFrame and I need the report parameters to be displayed on the HTML page and not in the report (because they are ugly).
Is there any way to use the reports dataset or something else to pass the parameters to the web page, when the page is generated or is the only way to do this by making backend SQL-queries and generating the parameter selectors based on that?
Getting parameters out
Your option would be to build a web application that communicates with the SQL Server Reporting Services by SOAP. This can allow you to programmatically load the parameters from a report and handle them in your web application (like display them on your web page). This can be written in a language of your choosing as long as it supports SOAP and Web services to consume the WSDL. You can see the reference article for consuming WSDL here: Accessing the SOAP API.
The methods required to achieve your goal are listed here: Report Parameters Methods.
Getting data back in
You can pass report parameters within a URL. The standard method is to append &ParameterName=Value onto the end of the URL. However, to do so the URL you construct must adhere to specific structure:
http://hostname/ReportServer?/RootDirectory/SubFolder/ReportName.rdl&ParamaterName=Value
You can pass more than one parameter into a URL by simply appending more after the first. For more detailed information please see the Microsoft article: Pass a Report Parameter Within a URL.
This question comes from the following post:
OWIN cookie authentication get roles on client side
I've created a separate thread for the question since it is more general than one in the post above.
In short:
Let's say we have a web application with javascript as client side + ASP.NET web api as server side and also an identity server. Only authenticated users can access web api endpoints, some of them accessible only for specific roles of user.
Now the client side of application should show specific items based on what role user is in. For example: user in administrator role can see an extra tab: manage items. There are two approaches to achieve this:
When rendering client side application, one could call an endpoind in web api which would return what roles user have. Based on that result, show/hide items in html.
When application loads, an endpoint, which returns how the structure should look like (for example: json string) would be returned, and based on that structure client application would be rendered. No show/hide html on client side based on roles in such case.
Now regarding 1st point: some could argue that there is a security leak, since malicious user can modify html to see elements that he is not supposed to see. But in this case he will not see any content from database and will not be able to load/update it since he will not be authorized to do that based on his role which is checked in server side.
2nd point seems more valid since we keep all identity related information logic on server side. And also all unnecessary content is not in html (while in 1st point it's hidden) - so that leads to better performance? In this case though if for example developing angular application, the json structure of application should include such information as name of angular controller and route for example. Would that not add complexity to developing application?
Assume that the application itself have a lot of roles and a lot of items should be visible/not visible based on these roles.
Pros/cons between 1st and 2nd? Thanks!
I stick always with the first suggested point.
As you mentioned the second choice will add more complexity for developing. For the 1st there is no security leak. If you don't want your users to modify the html and to access forbidden areas in your application simply use ng-if instead of ng-show. If you are not familiar - ng-if will not just hide the content with display: none;. It will completely remove it from the DOM and this leading the user unable to show that content as it is not in the DOM.
Read this for more detailed explanation for ng-if and ng-show: what is the difference between ng-if and ng-show/ng-hide
I usually have an endpoint getting information about the user - including it's role and save that user into a service (factory). This gives me the flexibility to use it everywhere in the application and check if the user has access or not to certain parts of it.