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Ngfor multidimensional array

By | 11.10.2020

Multidimensional Arrays (C# Programming Guide)

The template element is the element the directive is attached to. I want to display orders in Angular. An object that is not Array. Such arrays are called as multidimensional arrays.

We can nest muliple NgFor directives together. For example, the following declaration creates a two-dimensional array of four rows and two columns. So we will write array[2] in the second h3 heading level tag. We highlight every other row by applying a CSS class when the row is odd. The simplest form of a multi-dimensional array is a two-dimensional array.

We use the NgFor directive to loop over an array of items and create multiple elements dynamically from a template element. We can pass to it any kind of Javascript Iterable in general, including Iterables that are created by the framework itself. The local variables are index, first, last, even, odd. The function also 'Select Object via string' is an approach that uses an object that works.

It seems like the GridLayout would be a good choice. Angular HTML binding. We can get the index of the item we are looping over by assigning index to a variable in the NgFor expression.

To display a list of heroes, begin by adding an array of hero names to the component and redefine myHero to be the first name in the array. By the way, the QueryList object is also iterable and works with ngFor.

Unfortunately, it really works by using the string array from 1 and converting the value from string to object and back. Angular provides NgForOf directive with ngFor selector. Add some css style to the app. This variable is then accessed within the template using interpolation. Angular provides an even value too. The NgForOf has local variables that can be used in iteration. Arrays can have more than one dimension.

In this example, we have been passing to ngForan array of Javascript objects, but actually we don't necessarily need to pass in an array to ngFor in order for it to work.

TypeScript supports the concept of multi-dimensional arrays. It instantiates a template for every element of given iterator. The following example uses the directive to show all of the values in an array property. I was able to put an ngFor on a Label to set the col, but I'm not sure how to nest another ngFor in order to increment the row.

It's late, so I'm heading off to bed, but I'll try to update tomorrow. This loop will loop through all elements in the array and display each of them in the view.

Thanks to Pradeep Jain for the In the code snippet below we use the ngFor directive to iterate over the people array and store each item in a template variable called person. I have a two dimensional array I would like to display in my app.GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Already on GitHub? Sign in to your account. I'm having trouble creating a select in Angular2 that is backed by an array of Objects instead of strings. I can do 4 or 5 if that's the intended way, but they seem pretty clunky. Is there another approach? Am I just too early in the alpha? Did I do something silly? I have run into this problem as well.

Was attempting to loop through an array of state abbreviations. We're experiencing this too. We'd like to be able to use ngFor inside of a select and access the object representing the option when it's selected.

Actually, wouldn't setting [ ngModel ] to "objValue. Test case 2 seems logical to me, but still doesn't work in beta. The value appears to be converted to a string, which results in [object Object]. I'm attempting to implement some cascading dropdowns, being able to use objects as the value would make this much easier.

I use a string property in my component now for 2 way binding to the view, and an additional change listener which picks the corresponding object from the list of available objects. I could not get the above hack from slintes to work at first. Interesting to note that the order of the ngModel and the ngModelChange is important. For reference, we are using 2. Any plans on fixing this? The Firefox and IE select bug is a separate issue: Thank you, kara!

I look forward to trying this out. Update once goes in :.

17-Angular 6 (ngFor Group By for Nested Array of Objects) By Eng-Ahmed Rabie - Arabic

You can still use [value] the same way as before for option values that are not objects. I tried the ng-value code approach, including the way the objects are set up. Its different than the suggestions for using ngControl. I'm using beta. I get this error: The line numbers don't match up with anything in my code.

Reply to this email directly or view it on GitHub comment. Let us never negotiate out of fear, but let us never fear to negotiate. Property bindings are always camel case.In this tutorial, we will understand ngfor using a simple example.

This example will help you to understand how to display the array data using ngfor template. Especially, the easiest way to display the component property or you can say the class variable is to bind the property using name through interpolation.

So in this tutorial, we will create the title using the component property and display it. Then create an array variable in component and display them in the view. In this article, you will learn how to set up the environment of angular and also how to create your first angular app. Now in this file structure, we will only work in the app directory which is inside the src folder. Each file has a different extension. Just focus on the app folder inside the src folder.

Using component. Then using the component. Go to the app. In this file, we will create some properties for the component. In the component, you will find the selector property.

Selector property use to select the component using the name. So app-root is the default component angular created for us. So angular provided the name of the HTML file of that component. In the styleurls angular specify the name of the css style file.

In the app component class, we created a title property and specify the string.

Angular ngFor - Learn all Features including trackBy, why is it not only for Arrays?

In this array, we write some cities names. After that create city property and specify the array zero index value to it. Here we create a div and align the text to center. Then we will make two h3 level of heading tag and specify the array index values to it. In this tag we will specify the name of the array and specify the index of the array. So we will write array[2] in the second h3 heading level tag. This loop will loop through all elements in the array and display each of them in the view.

So the city is the formal variable which only exists in the li tag. So you can access this in the li tag. We are not creating a thousand line of code in this tutorial to styling the component. So we will just add the array class which we specify to the division element of ul tag and specify the display and justify-content property. If you have any question then comment me in the video comment section and share this article to your friends. Thank You. We will show you the best way to create the Hamburger Menu animation with….

How to Add Bootstrap 4. Here is the Example which we are creating in this tutorial. First, we will create a new angular Application with this command.In this post we are going to go over the ngFor core directive, namely we are going to go over the following:.

So let's get started diving into ngFor! Below you can also find a video version of this post if you prefer, and the running code of this post is available here. The core directive ngFor allows us to build data presentation lists and tables in our HTML templates.

Let's take for example the following data:. With ngFor we can print this data to the screen under the form of a data table, by generating HTML similar to this:. This template will generate the HTML table that we showed just above. We can see in this example the most common syntax for using ngFor :.

Note that the loop variable hero is only visible inside the loop, you would not be able to access it outside the ngFor section. If you have an AngularJs background, you will see this error a few times before you get used to the new Angular syntax:.

This is because you have accidentally either used item in items instead of item of itemsor forgot to add the let keyword at the beginning of the expression:.

A very common requirement is to add to a list the numeric index position of its element. We can get the index of the current element by using the index variable:. Note that you need the let keyword to get the value of the index, otherwise you will get an error similar to this one:.

Another very common functionality needed when building tables is to be able to stripe a table by adding a different css class to the even or odd rows. Let's say that to the above table we want to add a CSS class even if the row is even and the CSS class odd if the row is odd. In order to so, we have a couple of variables available for that: even and oddthat can be used in the following way together with ngClass :. Just like the even and odd functionality, there are also two other variables that can be used to identify the first and the last elements of the list:.

This will add a CSS class named first to the first element of the list, and a CSS class named last to the last element of the list:. As the input list gets modified, ngFor will try to avoid to constantly create and destroy the DOM elements of the list, as this is an expensive operation.

Also, when we pass to ngFor a new list, this does not mean that the whole list will be re-built, meaning all the DOM re-created. Many of the existing DOM elements will be reused and only some values inside them will be overwritten, and the decision is taken for each element in the list separately. In order to take that decision Angular needs to identify each list element in a unique way, because for example if we pass in a new list with a different order, Angular will try to identify the elements and re-order the DOM elements of the list without deleting them and recreating them.

This means that if you build a list of new objects from scratch with the exact same values as the previous list and pass this newly built list to ngForAngular will not be able to tell that a given list item is already present or not.In this quick how-to tutorial we'll be learning about the ngFor directive in Angular and how to use it to display arrays of data in your Angular templates.

For example, let's consider the following array of objects representing a set of products in a component:. Let's see how ngFor works by building a practical example. We'll only see how to create a component with an associated HTML template so you should already have an Angular development environment ready with Angular CLI v9 installed and a project generated.

Both these two things can be done with the following two commands:. Go ahead and navigate inside inside your project's folder and generate a component with the following commands:. Let's understand the basic syntax if ngFor :. The variable used to represent the data availabe for each iteration inside an ngFor directive is only only visible inside the loop.

You can get the index of the current element in the ngFor loop by using the index variable:. Check out this tutorial for a complete Angular 8 example that demonstrates how we can use ngFor to display an array of fetched data in our HTML template. We'll be using Angular 9 for the example. We'll learn about these things: What ngFor does in Angular and how it's used?

How to find the index position of an element inside an ngFor loop? Getting the first and the last element inside an ngFor loop Let's get started with our tutorial to master ngFor in Angular! What ngFor does in Angular and how it's used? Sponsored Links. What Is Angular 9 ivy? How to add Bootstrap 4 to my Angular 9 app? How to Install and Use jQuery with Angular 9? Let's stay connected!

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Your top level iteration is wrong, the array you want to iterate is inside members. Learn more. Angular 2 using nested ngFor Ask Question. Asked 3 years, 5 months ago. Active 3 years, 5 months ago. Viewed 13k times. I get this error when using the below code: Cannot find a differ supporting object '[object Object]' of type 'object'. Is there any way to workaround this problem when doing nested ngFor? Matthew Green 9, 4 4 gold badges 33 33 silver badges 51 51 bronze badges.

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The Overflow Bugs vs. Featured on Meta. Responding to the Lavender Letter and commitments moving forward. Linked 1. Related Hot Network Questions. Question feed. Stack Overflow works best with JavaScript enabled.We will discover, how we can use the ngFor directive to display multiple elements directly from a JavaScript array.

Also, we will take a look at the utilities of the ngFor directive, like the index, or even and odd. When we got the basics, we will move on to some more advanced topics like change-detection and DOM manipulation to tweak the performance of our for-loop using trackBy. We can use this directive, if we want to display a dynamic list, for example, an array of elements on the screen. This array could look like this example data:.

That array could be static and look like the array above or could be filled at runtime. So to create a list-element for each array element, we place the ngFor directive inside of the li tag. Did you notice that the syntax looks like a regular forEach loop? Well, actually it works quite the same way. With the statement "let element of array" we are defining a variable "element", that holds a reference to the current array element.

Knowing that we can now add the persons' name and the age to each list element. We do so by using the "element" variable we defined inside of the ngFor directive:. Again, this behavior is quite similar to a regular forEach loop. The defined variable e. For example, if we wanted to number each list-element. We would not only require each element, but also its index inside of the array.

To get the index of each element, we can define another variable in the ngFor directive. We can name that variable however we like. Let's call it "i" for now. To get the value of the index, we also need to assign "index" to that variable. Afterward, we can use "i" inside of the directives' scope, just like the other variables. We can also get the first "first" or the last "last" element by assigning its value to a variable, as well.

The value of the variable is boolean, depending if the current element is first or last. This makes sense, if we want to style the first or the last element of the list differently. Using this variables, we can then assign each of them a different class:. Just like first and last, this is useful if we want to style elements with an even index differently than those with a odd index. This is commonly used in tables, to increase readability. In that example, every second row has a slightly different color.

Well, first of all, manipulations to the DOM are quite expensive performance wise, compared to regular JavaScript code. To reduce DOM-manipulation to a bare minimum, angulars' ngFor directive is heavily optimized.

For example, if a element is added to the array, it is not re-rendering the whole list. Instead, all the existing DOM-elements are re-used and only the additional element is created. Furthermore, when a element changes its position in the array, angular notices that and only changes the position of the one DOM-element.

To do all that optimization though, angular needs a way to identify each object in the array. Otherwise it cannot determine what happened. By default, it uses the reference of the object for that. Unfortunately, the default method of identifying objects by reference is quite limited in many cases. Especially in scenarios where a change of the reference cannot be avoided.


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