Formarray

Sign up.

In this post, you are going to learn everything that you need to know about the Angular FormArray construct, available in Angular Reactive Forms. We are going to learn exactly what is an Angular FormArray , what is the difference towards a normal FormGroup , when to use it and why. We are going to give an example of a common use case that would be hard to implement without a FormArray : an in-place editable table with multiple form controls per line, where new editable rows can be added or removed on demand by the user. This post is part of our ongoing series on Angular Forms, you can find all the articles available here. So without further ado, let's get started learning everything that we need to know about Angular FormArray! In most cases, all the form fields of a form are well known upfront, and so we can define a static model for a form using a FormGroup :. As we can see, using a FormGroup , we can define a group of related form controls, their initial values, and form validation rules, and give property names for each field of the form.

Formarray

.

Formarray Gechev. As we can see, the FormArray container is ideal for those rarer situations when we don't know the number of form controls upfront or their names, formarray.

.

Sign up. Sign in. Netanel Basal. This article assumes that you have a least some working knowledge of Angular FormGroup and FormControl. As you probably know, when we create an AbsractControl such as FormGroup or a FormControl , we can use an array as our value.

Formarray

While building forms for our apps, most of the time we know in advance what fields the user needs, so we statically lay them out in our templates. But sometimes, we come across a particular data point which can have variable numbers of inputs. So for example, we can have form inputs such as interests or hobbies. Some users might have 2 hobbies, others might have 5 and so on. We need a way for the user to dynamically add and remove form controls, so that they can enter the required number of inputs. Something like the following. As we change the number of value, the form array value gets updated as well! Let's then create our form array in our app component ts file. We'll call it hobbiesArray and this will be a new FormArray.

Synonym for son

Next, like the previous example, we need to loop over the FormArray controls:. Custom directives are a powerful feature in Angular that allows you to extend the functionality of HTML elements. An example would be a form that is fully dynamically built according to data coming from the backend! As a result, we can see properties it has in common with them, such as valid , dirty , disabled , etc. Frontend Weekly. In our case, all the controls inside the editable table are going to be inside the FormArray instance, built using the fb. As we can see, in order to add a row to the table, we are first creating the form model of a simple form with only the two fields of each row: the lesson title and difficulty. Now, for the final step:. We have added to the component a getter for the lessons property, in order to make it simple to access the FormArray instance in a simple and type-safe way. To conclude our exercise, we will now show the full code of the editable table component, and review the template. Or we can hold it in a property :.

In this post, you are going to learn everything that you need to know about the Angular FormArray construct, available in Angular Reactive Forms. We are going to learn exactly what is an Angular FormArray , what is the difference towards a normal FormGroup , when to use it and why. We are going to give an example of a common use case that would be hard to implement without a FormArray : an in-place editable table with multiple form controls per line, where new editable rows can be added or removed on demand by the user.

The Software Line. Removes all the elements from the array:. Each control will then have a numeric position in the form controls array, instead of a unique name. The release of version v Let's quickly summarize everything that we have learned about FormArray , and do one final comparison to FormGroup. The traditional way to do it is by using a getter function that obtains a reference to the FormArray control from the parent FormGroup :. In this case, the FormArray validity status is determined based on its AbstractControls validity. This is just to keep the example simple, but nothing would prevent us from adding any other form properties if we needed to. As we can see, the FormArray container is ideal for those rarer situations when we don't know the number of form controls upfront or their names. In most cases, all the form fields of a form are well known upfront, and so we can define a static model for a form using a FormGroup : As we can see, using a FormGroup , we can define a group of related form controls, their initial values, and form validation rules, and give property names for each field of the form.