set the default value in the mat select dropdown when the page loads

Question

set the default value in the mat select dropdown when the page loads

I have been working on creating a form using Angular Material. I am able to successfully get and set values in text fields or text area fields, but I am having trouble setting values in a dropdown menu. My form has two JSON data sets - the first one fills the dropdown with options, and the second one is supposed to set the default value in the dropdown. However, when the page loads, the default value is not getting set.

createProductForm(): FormGroup {
    return this._formBuilder.group({
      CATEGORY: [this.product.categories]
    });
  }


 ngOnInit() {
  getAllCategory=[
{"TYPE_CODE": "CATEGORY","TYPE_DESC": "PUBLIC"},
{"TYPE_CODE": "CATEGORY","TYPE_DESC": "PRIVATE"},
{"TYPE_CODE": "CATEGORY","TYPE_DESC": "SYSTEM"},
]

defaultSelectCategory=[
{"CATEGORY": "PRIVATE"}
]

this.defaultCat = defaultSelectCategory[0].CATEGORY;
}




<mat-form-field appearance="outline" fxFlex="100">
   <mat-label>Project</mat-label>
   <mat-select formControlName="CATEGORY" [(value)]="defaultCat" required >
     <mat-option *ngFor="let item of getAllCategory" value="{{item.TYPE_DESC}}" (onSelectionChange)="getCATEGORY(item)">
       {{item.TYPE_DESC}}
     </mat-option>

   </mat-select>
     <mat-icon matSuffix class="secondary-text">outlined_flag</mat-icon>
   </mat-form-field>

I can't figure out why the default value is not being set for the dropdown on page load. Also, it happens to be my birthday today, so don't forget to wish me - lol!

angular typescript angular-reactive-forms angular-material-7

Answer 1

Answer №1

Consider implementing ngModel for better functionality

<div>
  <mat-select [(ngModel)]="selectedOption">
    <mat-option *ngFor="let item of listOptions" [value]="item.itemId">{{ item.itemName }}</mat-option>
  </mat-select>
</div>

Make sure to include square brackets in the mat options for correct display

Answer 2

Consider implementing ngModel for better functionality

<div>
  <mat-select [(ngModel)]="selectedOption">
    <mat-option *ngFor="let item of listOptions" [value]="item.itemId">{{ item.itemName }}</mat-option>
  </mat-select>
</div>

Make sure to include square brackets in the mat options for correct display

Answer 3

Answer №2

Your code has several issues that need to be addressed. It is incorrect to declare variables (getAllCategory, defaultSelectCategory) inside ngOnInit(). Instead, you should declare them at the top of your code and access them within ngOnInit() using the 'this' keyword.

I have created a functioning version of your code here - https://stackblitz.com/edit/angular-5r6u3p-dhwgqm Please take a look at it.

Date Picker HTML

<mat-form-field appearance="outline" fxFlex="100">
<mat-label>Project</mat-label>
<mat-select [(value)]="defaultCat" required>
    <mat-option *ngFor="let item of getAllCategory" value="{{item.TYPE_DESC}}"
        (onSelectionChange)="getCATEGORY(item)">
        {{item.TYPE_DESC}}
    </mat-option>
</mat-select>
<mat-icon matSuffix class="secondary-text">outlined_flag</mat-icon>

Date Picker TS

export class DatepickerValueExample {
  getAllCategory=[
    {"TYPE_CODE": "CATEGORY","TYPE_DESC": "PUBLIC"},
    {"TYPE_CODE": "CATEGORY","TYPE_DESC": "PRIVATE"},
    {"TYPE_CODE": "CATEGORY","TYPE_DESC": "SYSTEM"},
  ]
  defaultSelectCategory=[
    {"CATEGORY": "PRIVATE"}
  ]
  defaultCat;

  ngOnInit() {
    this.defaultCat= this.defaultSelectCategory[0].CATEGORY;
  }

  getCATEGORY() {
  }
}

Answer 4

Your code has several issues that need to be addressed. It is incorrect to declare variables (getAllCategory, defaultSelectCategory) inside ngOnInit(). Instead, you should declare them at the top of your code and access them within ngOnInit() using the 'this' keyword.

I have created a functioning version of your code here - https://stackblitz.com/edit/angular-5r6u3p-dhwgqm Please take a look at it.

Date Picker HTML

<mat-form-field appearance="outline" fxFlex="100">
<mat-label>Project</mat-label>
<mat-select [(value)]="defaultCat" required>
    <mat-option *ngFor="let item of getAllCategory" value="{{item.TYPE_DESC}}"
        (onSelectionChange)="getCATEGORY(item)">
        {{item.TYPE_DESC}}
    </mat-option>
</mat-select>
<mat-icon matSuffix class="secondary-text">outlined_flag</mat-icon>

Date Picker TS

export class DatepickerValueExample {
  getAllCategory=[
    {"TYPE_CODE": "CATEGORY","TYPE_DESC": "PUBLIC"},
    {"TYPE_CODE": "CATEGORY","TYPE_DESC": "PRIVATE"},
    {"TYPE_CODE": "CATEGORY","TYPE_DESC": "SYSTEM"},
  ]
  defaultSelectCategory=[
    {"CATEGORY": "PRIVATE"}
  ]
  defaultCat;

  ngOnInit() {
    this.defaultCat= this.defaultSelectCategory[0].CATEGORY;
  }

  getCATEGORY() {
  }
}

Answer 5

Answer №3

To start with, here are a couple of suggestions:

If you're using model-driven forms (with ReactiveFormsModule), there's no need for the [(value)] attribute
You can remove the required attribute from the mat-select form to avoid unnecessary console warnings
Your default value doesn't have to be an array; you can use it directly as an object instead
It's better to move your value setter and required validation to your model

Update your default value to an object or utilize the same array without repetition:

this.defaultSelectCategory = this.getAllCategory[1];

Next, assuming your dropdown formControlName is set up like this:

CATEGORY: new FormControl(this.defaultSelectCategory.TYPE_DESC, [Validators.required]),

Update your HTML accordingly:

<mat-form-field appearance="outline" fxFlex="100">
  <mat-label>Project</mat-label>
  <mat-select formControlName="CATEGORY">
  <mat-option *ngFor="let item of getAllCategory" [value]="item.TYPE_DESC">
    {{item.TYPE_DESC}}
  </mat-option>

 </mat-select>
 <mat-icon matSuffix class="secondary-text">outlined_flag</mat-icon>

Answer 6

To start with, here are a couple of suggestions:

If you're using model-driven forms (with ReactiveFormsModule), there's no need for the [(value)] attribute
You can remove the required attribute from the mat-select form to avoid unnecessary console warnings
Your default value doesn't have to be an array; you can use it directly as an object instead
It's better to move your value setter and required validation to your model

Update your default value to an object or utilize the same array without repetition:

this.defaultSelectCategory = this.getAllCategory[1];

Next, assuming your dropdown formControlName is set up like this:

CATEGORY: new FormControl(this.defaultSelectCategory.TYPE_DESC, [Validators.required]),

Update your HTML accordingly:

<mat-form-field appearance="outline" fxFlex="100">
  <mat-label>Project</mat-label>
  <mat-select formControlName="CATEGORY">
  <mat-option *ngFor="let item of getAllCategory" [value]="item.TYPE_DESC">
    {{item.TYPE_DESC}}
  </mat-option>

 </mat-select>
 <mat-icon matSuffix class="secondary-text">outlined_flag</mat-icon>

set the default value in the mat select dropdown when the page loads

Answer №1

Answer №2

Answer №3

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