Lectures: Fix an issue with undefined units when processing lecture units

[eceeeren]

Checklist

General

• I tested all changes and their related features with all corresponding user types on a test server.
• This is a small issue that I tested locally and was confirmed by another developer on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Client

• Important: I implemented the changes with a very good performance, prevented too many (unnecessary) REST calls and made sure the UI is responsive, even with large data (e.g. using paging).
• I strictly followed the client coding and design guidelines.
• Following the theming guidelines, I specified colors only in the theming variable files and checked that the changes look consistent in both the light and the dark theme.
• I added multiple screenshots/screencasts of my UI changes.

Motivation and Context

This issue is created because when a new Lecture is created and Lecture Unit Processing is executed, if the PDF file does not have a page titled "Outline", then the units can not be created, therefore they become 'undefined'. Since there was no checks on the HTML page regarding the units being undefined, these checks needed to be added.

Problem Video:
https://github.com/user-attachments/assets/660d1380-4fee-43c5-b275-925fdc0ffe78

Description

For createAttachmentUnits() button and noUnitDetected warning, one more check added, that checks if the units exists or not

Steps for Testing

Prerequisites:

• 1 Instructor

1. Navigate to 'Create Lecture' page
2. Select 'Automatic Unit Processing'
3. Upload a PDF file without an "Outline" slide
4. Observe the page, it should not give an error and show "No units are found" warning
5. There should be no lecture units and Submit button should be disabled until you add a unit
6. Check if submits after creating at least 1 unit
7. Create a Lecture again and upload a file with "Outline" slide
8. The lecture units should be created, no warnings/errors should be shown

Testserver States

Note

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Review Progress

Performance Review

• I (as a reviewer) confirm that the client changes (in particular related to REST calls and UI responsiveness) are implemented with a very good performance even for very large courses with more than 2000 students.
• I (as a reviewer) confirm that the server changes (in particular related to database calls) are implemented with a very good performance even for very large courses with more than 2000 students.

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1
• Test 2

Screenshots

Before the Fix:

After the Fix:

Summary by CodeRabbit

Summary by CodeRabbit

• Bug Fixes
  • Enhanced handling of the units array to ensure existing units are preserved if the response does not contain new units.
  • Updated button states for creating and deleting attachment units to simplify conditions related to the units array.

[coderabbitai]

Walkthrough

The changes in this pull request involve modifications to the conditional logic in the attachment-units.component.html and attachment-units.component.ts files. Specifically, the conditions checking the units array have been simplified by removing checks for the array's initialization. Additionally, the handling of the units property in the AttachmentUnitsComponent class has been updated to retain previous values if the response from a service does not provide new units.

Changes

File	Change Summary
src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html	Simplified conditional checks for the units array and updated button disabled states accordingly.
src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.ts	Modified assignment of this.units to retain previous values if the response does not provide new units.

Possibly related PRs

• Development: Fix failing attachment client test #8573: This PR modifies the attachment-unit-form.component.spec.ts, which is related to the attachment units, similar to the changes made in the attachment-units.component.html and attachment-units.component.ts files in the main PR.
• Lectures: Refactor lecture units to prevent horizontal scrolling #8940: This PR refactors lecture units, which may relate to the handling of units in the main PR, particularly in how they are displayed and managed in the UI.
• Learning analytics: Fix missing name of attachment lecture units on student dashboard #8781: This PR addresses the display of attachment lecture units, which connects to the changes made in the main PR regarding the handling of the units array in the context of attachment units.

Suggested labels

tests

Suggested reviewers

• JohannesStoehr
• MaximilianAnzinger
• FelixTJDietrich
• pzdr7

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[coderabbitai]

Actionable comments posted: 1

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: ASSERTIVE

📥 Commits

Files that changed from the base of the PR and between b6b47e7 and 60371b4.

📒 Files selected for processing (1)

• src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html (2 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html (1)

Pattern src/main/webapp/**/*.html: @if and @for are new and valid Angular syntax replacing *ngIf and *ngFor. They should always be used over the old style.

🔇 Additional comments (2)

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html (2)

Line range hint 102-107: Improved robustness in handling undefined units

The change from @if (units && units.length < 1) to @if (!units || units.length < 1) enhances the code's ability to handle cases where units might be undefined or null. This modification ensures that the warning message is displayed not only when the units array is empty but also when it's not initialized.

The use of @if adheres to the new Angular syntax guidelines, which is excellent.

---

Line range hint 1-126: Summary: Improved handling of undefined units

The changes in this file successfully address the PR objectives by enhancing the robustness of the code when dealing with potentially undefined units. The use of the new Angular syntax (@if) is consistent with the coding guidelines.

The modifications effectively prevent errors that could occur when a PDF without an "Outline" slide is uploaded, as mentioned in the PR objectives. The code now gracefully handles cases where units might be undefined or empty.

No major issues were found, and the changes are approved with a minor suggestion for further improvement.

[coderabbitai]

Actionable comments posted: 1

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: ASSERTIVE

📥 Commits

Files that changed from the base of the PR and between cfe507a and f7829f1.

📒 Files selected for processing (2)

• src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html (1 hunks)
• src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.ts (1 hunks)

🧰 Additional context used

📓 Path-based instructions (2)

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html (1)

Pattern src/main/webapp/**/*.html: @if and @for are new and valid Angular syntax replacing *ngIf and *ngFor. They should always be used over the old style.

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.ts (1)

Pattern src/main/webapp/**/*.ts: angular_style:https://angular.io/guide/styleguide;methods_in_html:false;lazy_loading:true;code_reuse:true;tests:meaningful;types:PascalCase;enums:PascalCase;funcs:camelCase;props:camelCase;no_priv_prefix:true;strings:single_quotes;localize:true;btns:functionality;links:navigation;icons_text:newline;labels:associate;code_style:arrow_funcs,curly_braces,open_braces_same_line,indent_4;memory_leak_prevention:true;routes:naming_schema;chart_framework:ngx-charts;responsive_layout:true

🔇 Additional comments (3)

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.html (3)

Line range hint 1-124: Summary of changes and recommendations

The modifications in this file aim to simplify the handling of the units array and align with the new Angular syntax (@if). While these changes address the PR objectives of fixing the undefined units problem, there are opportunities to enhance robustness:

1. Consider adding null checks using the safe navigation operator (?.) when accessing units.length.
2. Ensure consistent handling of potential null or undefined values for units throughout the template.

These recommendations will help prevent potential runtime errors and improve the overall reliability of the component.

---

Line range hint 111-111: Ensure consistent and safe handling of the units property.

The change to [disabled]="units.length < 1" is consistent with the earlier modification. However, to maintain robustness and prevent potential runtime errors, consider using the safe navigation operator:

[disabled]="units?.length < 1"

This change ensures consistency with the earlier suggestion and provides a safeguard against potential undefined or null values for units.

To verify the necessity of this change, we can check if there are any other occurrences of units.length without a null check:

#!/bin/bash
# Search for usages of 'units.length' without null check
rg --type html "(?<!units\?)\bunits\.length" src/

---

102-102: ⚠️ Potential issue

Consider adding a null check for robustness.

While the simplification of the condition aligns with the new Angular syntax, it might introduce a potential runtime error if units is undefined or null. To ensure robustness, consider adding a null check:

@if (units?.length < 1) {

This change maintains the simplicity while safeguarding against potential undefined or null values for units.

To verify the necessity of this change, we can check if units is ever assigned a null or undefined value:

✅ Verification successful

Verification Successful: No null or undefined assignments for units.

Based on the analysis, the units property is never assigned null or undefined values within the codebase. Therefore, the current condition @if (units.length < 1) is safe and does not require a null check.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Search for assignments to 'units' property
rg --type typescript "this\.units\s*=\s*(null|undefined)" src/

Length of output: 283

---

Script:

#!/bin/bash
# Search for assignments to 'units' property using PCRE2
rg --pcre2 --type typescript "this\.units\s*=\s*(null|undefined)" src/

Length of output: 107

---

Script:

#!/bin/bash
# Search for assignments to 'units' property in .ts and .tsx files using PCRE2
rg --pcre2 "this\.units\s*=\s*(null|undefined)" --glob "*.ts" --glob "*.tsx" src/

Length of output: 83

[ole-ve]

code

[coderabbitai]

Actionable comments posted: 1

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: ASSERTIVE

📥 Commits

Files that changed from the base of the PR and between f7829f1 and c2d9f48.

📒 Files selected for processing (1)

• src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.ts (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.ts (1)

Pattern src/main/webapp/**/*.ts: angular_style:https://angular.io/guide/styleguide;methods_in_html:false;lazy_loading:true;code_reuse:true;tests:meaningful;types:PascalCase;enums:PascalCase;funcs:camelCase;props:camelCase;no_priv_prefix:true;strings:single_quotes;localize:true;btns:functionality;links:navigation;icons_text:newline;labels:associate;code_style:arrow_funcs,curly_braces,open_braces_same_line,indent_4;memory_leak_prevention:true;routes:naming_schema;chart_framework:ngx-charts;responsive_layout:true

🪛 Biome

src/main/webapp/app/lecture/lecture-unit/lecture-unit-management/attachment-units/attachment-units.component.ts

[error] 120-120: Forbidden non-null assertion.

Unsafe fix: Replace with optional chain operator ?. This operator includes runtime checks, so it is safer than the compile-only non-null assertion operator

(lint/style/noNonNullAssertion)

[github-actions]

⚠️ Unable to deploy to test servers ⚠️

The docker build needs to run through before deploying.

[magaupp]

Tested on TS4. Works as expected.
PDFs without outline slides are processed without errors and the "No unit was detected" message is shown.
PDFs with outline slides are processed correctly.