Angularjs showing a string if the object is null in an html table

Question

<td ng-repeat="course in student.extracourses">
    <div ng-if="!course">  not selected   </div>
    {{b.note}}
</td>

I have a table with some static columns and dynamic columns with respect to student extracourses. Some students do have extra notes and some do not. How can I show in the table 'not selected' if the 'course' does not exist? I tried this code above and it did not print 'not selected' for those who do not have a course

I think ng-repeat will only show the student with course and there is no meaning of ng-if inside that. — Sonal Borkar
– Sonal Borkar, Commented Feb 18, 2019 at 20:33
Seems like a logic error. If a student does not have a course then it would probably not be included in their course collection (student.extracourses) — Igor
– Igor, Commented Feb 18, 2019 at 20:35
@Igor if it does not have it, it returns an empty extracourses — Thunfische
– Thunfische, Commented Feb 18, 2019 at 20:37
That does not make sense (to me). So if there are 4 courses and the student is "enrolled" in 2 of them. Does the array extracourses contain 4 items or just 2? If it is 4 what is the value of the 2 "empty" courses in that collection? (undefined, null, empty object, something else....) — Igor
– Igor, Commented Feb 18, 2019 at 20:39

Obsidian Age · Accepted Answer · 2019-02-18 20:57:23Z

1

You can use <div ng-if="course === undefined"> to check whether course is set or not:

<td ng-repeat="course in student.extracourses">
  <div ng-if="course === undefined">not selected</div>
  {{b.note}}
</td>

Or alternatively, check the typeof():

typeof(course) === "undefined"

edited Feb 18, 2019 at 20:57

answered Feb 18, 2019 at 20:32

Obsidian Age

42.5k11 gold badges54 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Igor Over a year ago

I think for the ng-if you meant to write the inverse, otherwise you get "not selected" for everything that is defined. Also the an undefined will evaluate to falsey and an ng-if check on a truethy/falsey expression is perfectly valid.

Obsidian Age Over a year ago

Yes, I did mean the inverse. My apologies; fixed!

Collectives™ on Stack Overflow

Angularjs showing a string if the object is null in an html table

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related