Angular patchValue vs setValue and dates

ghz 7months ago ⋅ 67 views

Is there any significant difference between using patchValue or setValue to set the value on a form ? Also is there any difference or best practice regarding using moment or date obj ?

     if(startDate) {
        const date = moment(startDate).toDate();
        this.form?.patchValue({ startDate: date });
      }

      if(endDate) {
        const date = new Date(endDate);
        this.form.get('endDate').setValue(date);
      }

Either way it works as expected for me , so I am just wondering .

Answers

Both patchValue and setValue are methods provided by Angular's FormControl class to update the value of a form control. While they may seem similar, there are some differences between them:

  1. patchValue:

    • patchValue allows you to update only the specified properties of the form control without affecting other properties. It's useful when you want to update only a subset of the form control's properties.
    • It accepts an object where each key represents a form control's name and its corresponding value represents the new value for that control.
    • If the specified control doesn't exist in the form group, patchValue will not throw an error. It will simply ignore the control that doesn't exist.
    • Example: this.form.patchValue({ startDate: date })

  2. setValue:

    • setValue replaces the entire value of the form control with the provided value. It sets all the properties of the form control to the provided value, discarding any existing properties.
    • It accepts a single value as an argument, which must match the structure of the form control's value.
    • If you attempt to set a value for a control that doesn't exist in the form group, setValue will throw an error.
    • Example: this.form.get('endDate').setValue(date)

In your code examples, both patchValue and setValue are used correctly to set the value of the form control startDate and endDate respectively. The choice between them depends on your specific use case and requirements. If you only need to update specific properties of the form control, patchValue is more appropriate. If you want to replace the entire value of the form control, setValue is the way to go.

Regarding the use of moment versus Date objects, it ultimately depends on your project's requirements and preferences. moment provides additional functionality and flexibility for working with dates, such as parsing, formatting, and manipulating dates with ease. However, if you only need basic date functionality, using Date objects may be sufficient and can help reduce the size of your project's dependencies. If you're already using moment elsewhere in your project and need its features, then using it consistently may be beneficial for consistency and maintainability.

#forms