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ProjectOrientedSessions/Session05/React/Mosh React.md
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- [ ] Watch https://www.youtube.com/watch?v=SqcY0GlETPk&ab_channel=ProgrammingwithMosh
ProjectOrientedSessions/Session05/Session05 Additional Info.md
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## What is CORS? (Chat GPT)
### CORS (Cross-Origin Resource Sharing)
**What it is:** CORS is a browser security feature that blocks requests to a different domain unless explicitly allowed by the server.
### 🔐 What is CORS **really** for?
CORS is **not** about protecting the backend server.
It’s about **protecting users** from **malicious websites** using their browser as a weapon.
---
### 🧠 Imagine this attack:
You’re logged into your **bank** in one browser tab (`bank.com`).
Now, you visit a shady website in another tab (`evil.com`). That site has JavaScript that tries to send this:
```js
fetch('https://bank.com/api/transfer?amount=5000&to=hacker', {
credentials: 'include' // it sends your bank cookies!
});
```
➡️ If the browser allowed this freely, the request would go through **using your login session**, and you’d lose money.
---
### 💥 Enter CORS
So the browser says:
> “Hold on. This JavaScript is from `evil.com`, and it’s trying to talk to `bank.com`. I won’t let that happen **unless `bank.com` says it’s okay**.”
That’s why the **backend server** must respond with something like:
```http
Access-Control-Allow-Origin: https://mytrusteddomain.com
```
Only then will the browser say, “Okay, go ahead.”
---
### So the purpose of CORS is:
✅ To **restrict browsers** from sending or accepting responses from **cross-origin** sources
❌ Not to protect the backend
❌ Not to restrict Postman, curl, servers, or mobile apps
---
### 🔄 In Dev Work (like your React + API case):
- You’re running React at `http://localhost:5173`
- You’re running ASP.NET Core API at `https://localhost:7001`
- The browser sees this as two **different origins** → blocks the request unless CORS is enabled on the API.
---
### 🧪 Why Postman works:
- Postman isn’t a browser
- Postman doesn’t care about same-origin policy
- Postman just sends requests like your backend would
---
### ✅ Conclusion:
- **CORS is a browser feature to protect users**
- **It restricts frontend JavaScript from calling other domains unless explicitly allowed**
- **You must configure your server to say “Yes, I allow your frontend to talk to me”**
## Feature-based Folder Structure
>
## Explanation of the `agent.ts`
>
## React.FC
### what is `React.FC`?
- `React.FC` (or `React.FunctionComponent`) is a **TypeScript type** that you can use to type your functional React components.
- It **tells TypeScript** that:
- This component is a function
- It **receives props** (in your case, `Props`)
- It **returns JSX** (it returns something React can render)
---
### Why use it?
Here’s what you get when you use `React.FC`:
1. ✅ **Prop typing** — You get auto-complete and error checking for props.
2. ✅ **Children** are automatically included. (More on this below.)
3. ✅ **Cleaner code** because TypeScript understands the shape of the component.
---
### Without `React.FC`
You could just write:
```tsx
const TransportationCard = ({ transportation }: Props) => { ... }
```
You lose some "extra typing safety" like automatic `children` typing.
---
### Small Detail: `children`
When you use `React.FC`, **TypeScript automatically** allows your component to accept `children` too — even if you didn’t define it in your `Props`.
For example:
```tsx
<TransportationCard transportation={t}>
<p>Hello</p> // This would be valid automatically
</TransportationCard>
```
Because `children` is **always** part of a `React.FC`.
👉 If you **don't** use `React.FC`, and you want to accept `children`, you have to **manually** add it to your props.
---
### Some developers today...
**Some people** (even in big companies) prefer **NOT** to use `React.FC` anymore because:
- It **forces children** even when you don’t want children.
- It's **a little bit redundant** — you can already just type props without it.
> So in modern codebases, **both styles are OK** — it’s just a preference.
---
### Quick Summary:
| Using `React.FC` | Not using `React.FC` |
| :------------------------------------------- | :---------------------------------------------- |
| Good for simple, typed functional components | Good if you want full manual control over props |
| Auto-includes `children` prop | You must manually add `children` if needed |
| Easy and quick | More customizable |
---
## `CityDropdown` Component:
### 1. **State Variables**
```tsx
const [cities, setCities] = useState<City[]>([]);
const [selectedCity, setSelectedCity] = useState<number | undefined>();
```
- `cities`: holds the list of cities retrieved from the backend (starts empty `[]`).
- `selectedCity`: holds the currently selected city’s ID (`number`) or `undefined` if nothing is selected yet.
---
### 2. **Fetching Cities on Mount**
```tsx
useEffect(() => {
agent.Cities.list()
.then(setCities)
.catch((err) => console.error("error loading cities", err));
}, []);
```
- When the component **mounts** (`[]` dependency array = run once), it calls `agent.Cities.list()`.
- `agent.Cities.list()` presumably returns a promise that resolves to an array of `City` objects.
- On success → `setCities` updates the `cities` state.
- On failure → logs an error to the console.
---
### 3. **Rendering the Dropdown**
```tsx
<select
value={selectedCity}
onChange={(e) => setSelectedCity(Number(e.target.value))}
>
<option value="">Select a City</option>
{cities.map((city) => (
<option key={city.id} value={city.id}>
{city.title}
</option>
))}
</select>
```
- Renders a `<select>` (dropdown).
- Its value is bound to `selectedCity`.
- When the user changes the selection (`onChange`), it updates `selectedCity` by converting the selected `value` from a string to a number (`Number(e.target.value)`).
- The dropdown always starts with a placeholder option: **"Select a City"**.
- It dynamically creates an `<option>` for each city in the `cities` array:
- `key` and `value` are the city's `id`.
- Displayed text is the city's `title`.
---
### What is `useEffect`?
🔹 **`useEffect` is a React Hook**.
It **tells React to run some code after the component renders**.
In code:
```tsx
useEffect(() => {
agent.Cities.list()
.then(setCities)
.catch((err) => console.error("error loading cities", err));
}, []);
```
- This function (`() => { ... }`) **runs right after** the component is first shown (because of `[]` — the empty array).
- Inside it, you are **calling your API** (`agent.Cities.list()`) to get the cities.
- When the server **responds with a list of cities**, you **save** them into your component's memory (state) by calling `setCities(data)`.
---
### What is `useState`?
🔹 **`useState` is another React Hook**.
It **creates a piece of memory** for your component.
In code:
```tsx
const [cities, setCities] = useState<City[]>([]);
const [selectedCity, setSelectedCity] = useState<number | undefined>();
```
Here’s what is happening:
- `cities` is a variable that starts as an **empty array** (`[]`).
- `setCities` is a **function** you use to **change** the value of `cities`.
Same with `selectedCity`:
- `selectedCity` starts as `undefined` (nothing selected yet).
- `setSelectedCity` lets you **update** which city is selected.
---
## `TransportationCard` Component
### 1. **The Component Function**
```tsx
const TransportationCard: React.FC<Props> = ({ transportation }) => {
```
- This is a **React Functional Component**.
- It takes `transportation` from props (destructured directly).
- It **returns JSX** that shows the transportation info in a styled card.
---
### 2. **Inside the JSX**
#### 2.1 Left Side — Price and Button
```tsx
<div className="flex flex-col items-center">
<div className="text-blue-600 font-bold text-lg">
{transportation.price} Toman
</div>
<button className="bg-blue-500 text-white px-4 py-2 rounded-md mt-2 hover:bg-blue-600">
Select Ticket
</button>
</div>
```
- Shows the **price** (`price` field) styled with blue, bold text.
- Has a **Select Ticket** button — blue, rounded, changes shade on hover.
---
#### 2.2 Middle — Trip Info
```tsx
<div className="flex-1 mx-4 text-center">
<div className="font-semibold text-gray-700">
{transportation.companyTitle}
</div>
<div className="flex items-center justify-center mt-2">
<div className="mx-2">{transportation.fromCityTitle}</div>
<span className="text-gray-400">→</span>
<div className="mx-2">{transportation.toCityTitle}</div>
</div>
<div className="text-sm text-gray-500 mt-1">
{new Date(transportation.startDateTime).toLocaleDateString("en", {
hour: "2-digit",
minute: "2-digit",
})}
</div>
</div>
```
- Shows the **company name**.
- Shows **From → To** cities in a neat way with an arrow (`→`) between them.
- Shows the **departure time**:
- `startDateTime` is parsed using `new Date(...)`.
- `toLocaleDateString("en", { hour: "2-digit", minute: "2-digit" })` formats it to show just **hours and minutes**.
---
#### 2.3 Right Side — Company Logo
```tsx
<div className="w-12 h-12">
<img
src="/images/company-placeholder.png"
alt="company"
className="w-full h-full object-contain"
/>
</div>
```
- Displays a small company **logo image** (placeholder image for now).
- `object-contain` keeps the image inside the box without stretching.
## `TrasnportationSearchForm` Component
### 🧠 Main Concepts Used:
| Feature | Purpose |
| :------------------------ | :--------------------------------------------------------------------------- |
| `useState` | To **store and manage** the form inputs, cities, results, and loading status |
| `useEffect` | To **load the list of cities once** when the component appears |
| **Typing with models** | `City`, `TransportationSearchRequest`, `TransportationSearchResult` |
| **Event handling** | To update form values and trigger the search |
| **Conditional rendering** | Show "Loading", "No results", or "Results" dynamically |
| | |
---
### 📦 Let's break down the code:
#### 1. ✍️ States
```tsx
const [searchResults, setSearchResults] = useState<TransportationSearchResult[]>([]);
const [loading, setLoading] = useState(false);
const [cities, setCities] = useState<City[]>([]);
const [form, setForm] = useState<TransportationSearchRequest>({
fromCityId: undefined,
toCityId: undefined,
startDate: null,
endDate: null,
vehicleTypeId: undefined,
});
```
You define **4 states**:
- `searchResults`: List of found transportations
- `loading`: True/false if waiting for API
- `cities`: List of available cities
- `form`: The form input values the user is selecting
All typed properly ✅
---
#### 2. 📡 Fetch cities automatically (useEffect)
```tsx
useEffect(() => {
agent.Cities.list().then(setCities);
}, []);
```
**Meaning**:
- When the page **first loads**, it **calls the API** to get cities.
- `agent.Cities.list()` calls your backend, and when it gets the cities, it puts them into `cities` state.
- The empty `[]` **dependency array** means this happens **only once**, not every time anything changes.
---
#### 3. ✏️ Handle input changes
```tsx
const handleChange = (e: React.ChangeEvent<HTMLSelectElement | HTMLInputElement>) => { ... }
```
Whenever a user types/selects:
- You detect **which field** (`name`) and **what value** (`value`) they changed
- Update the `form` state accordingly:
- `fromCityId` and `toCityId` are converted to numbers (`parseInt`)
- `startDate` and `endDate` allow null
- Other fields (if any) are copied directly
---
#### 4. 🔍 Handle Search button
```tsx
const handleSearch = () => { ... }
```
When the user clicks **Search**:
- Set `loading` to `true`
- Call the backend API `agent.TransportationSearch.search(form)`
- When the result comes back:
- Save it into `searchResults`
- If error: log it
- Finally, set `loading` to `false` again
---
#### 5. 🖥️ Return (render) JSX
You build a UI:
- **Vehicle Types** (Bus, Train, Airplane) selectable with a click → sets `vehicleTypeId`
- **From City** and **To City** dropdowns
- **Start and End Date** inputs
- **Search Button** to trigger the search
- **Result area** that shows:
- If loading: "Loading..."
- If no results: "No results found"
- If results: List of `TransportationCard` components for each found item.
---
ProjectOrientedSessions/Session05/Session05 Backend.md
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# CORS (Backend Repository)
# 🛠️ Task Checklist
## CORS (Backend Repository)
- [ ] open `program.cs` and add the following lines - [ ] open `program.cs` and add the following lines
```c# ```c#
@@ -17,3 +19,9 @@ builder.Services.AddCors(options =>
app.UseCors("Frontend"); app.UseCors("Frontend");
``` ```
# 🧠 Hints & Notes
# 🙌 Acknowledgements
- ChatGPT for snippet refinement and explanations
# 🔍 References
ProjectOrientedSessions/Session05/Session05 Frontend.md
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# Preparation # 🛠️ Task Checklist
## Preparation
- [ ] Watch https://www.youtube.com/watch?v=SqcY0GlETPk&ab_channel=ProgrammingwithMosh - [ ] Watch https://www.youtube.com/watch?v=SqcY0GlETPk&ab_channel=ProgrammingwithMosh
## 🚧Branching (Project Setup)
# Important Note Before Starting
## From now on, this session will be focused on the **frontend repository**
## If you have already created a the frontend project, with the deprecated command(create-react-app), you need to first delete all that, commit the changes, and then create the project using the next instruction
# Branching
- [ ] Create the develop branch - [ ] Create the develop branch
- [ ] Create the feature/project-setup branch based on develop - [ ] Create the feature/project-setup branch based on develop
# Creating a project (using Vite) ## Creating a project (using Vite)
``` ```
npm create vite@latest alibabaclone-frontend --template react-ts npm create vite@latest alibabaclone-frontend --template react-ts
``` ```
# React Folder Structure ## React Folder Structure
- [ ] Create the folders as shown in the picture below - [ ] Create the folders as shown in the picture below
![[Pasted image 20250427154917.png]] ![[Pasted image 20250427154917.png]]
- [ ] move `App.tsx` and `App.css` to 'shared/layout/' - [ ] move `App.tsx` and `App.css` to 'shared/layout/'
- [ ] adjust the dependencies in these files and `index.html` - [ ] adjust the dependencies in these files and `index.html`
# Installing packages ## Installing packages
- [ ] run this command to install these packages: `uuid`, `react-router-dom`, and `axios` - [ ] run this command to install these packages: `uuid`, `react-router-dom`, and `axios`
```bash ```bash
npm install uuid react-router-dom axios npm install uuid react-router-dom axios
@@ -36,17 +28,14 @@ npm install uuid react-router-dom axios
npm install @reduxjs/toolkit react-redux npm install @reduxjs/toolkit react-redux
``` ```
# CSS TAILWIND ## CSS/Component Library
## **Important Note About CSS**
There are different ways to handle `CSS` styling when creating components. There are different ways to handle `CSS` styling when creating components.
You can choose any approach you prefer: You can choose any approach you prefer:
1. **Plain CSS** 1. **Plain CSS**
- Write regular `.css` files and import them into your components. - Write regular `.css` files and import them into your components.
2. **CSS Modules** 2. **CSS Modules**
- Create component-specific `.module.css` files to automatically scope styles. - Create component-specific `.module.css` files to automatically scope styles.
3. **TailwindCSS** 3. `**TailwindCSS**`
- A utility-first CSS framework where you apply classes directly in your HTML/JSX. - A utility-first CSS framework where you apply classes directly in your HTML/JSX.
4. **Sass / SCSS** 4. **Sass / SCSS**
- An extension of CSS with variables, nesting, and more features. Can be used alone or with modules. - An extension of CSS with variables, nesting, and more features. Can be used alone or with modules.
@@ -56,21 +45,20 @@ You can choose any approach you prefer:
- Example: Material-UI (MUI), Ant Design, Chakra UI, etc. - Example: Material-UI (MUI), Ant Design, Chakra UI, etc.
- These often include ready-made components with built-in styling. - These often include ready-made components with built-in styling.
- [ ] install the css/component library of your choice - [ ] install the css/component library of your choice
### For tailwind, use the link below (skip the first step) ### Tailwind
Tailwind If you use tailwind with ShadCN, use this link (skip the first step)
https://ui.shadcn.com/docs/installation/vite [Tailwind with ShadCN](https://ui.shadcn.com/docs/installation/vite)
# Merge
## 🚧Merge
- [ ] Create a PR and merge the current branch with develop - [ ] Create a PR and merge the current branch with develop
# Branching ## 🚧Branching
- [ ] Create the feature/transportation-search branch based on develop - [ ] Create the feature/transportation-search branch based on develop
# Creating Models ## Creating Models
- [ ] Create models for the DTOs that are used to convey data between backend and frontend - [ ] Create models for the DTOs that are used to convey data between backend and frontend
📂 Suggested Folder: shared/models/[relatedFolder] 📂 `Suggested Folder: shared/models/[RelatedFolder]`
Create a `[dtoName].ts` in the related folder, and define the model
## Example: ## Example:
```ts ```ts
export interface TransportationSearchRequest{ export interface TransportationSearchRequest{
@@ -82,14 +70,12 @@ export interface TransportationSearchRequest{
} }
``` ```
# Handling API Calls ## Handling API Calls
- [ ] Create `agent.ts` to handle API calls using axios - [ ] Create `agent.ts` to handle API calls using axios
📂 Suggested Folder: shared/api/ 📂 Suggested Folder: shared/api/
> Note: the name and the location of this file has changed since writing this note
- [ ] Adjust the `baseURL` to address your web API port - [ ] Adjust the `baseURL` to address your web API port
```ts ```ts
import axios, { AxiosResponse } from 'axios'; import axios, { AxiosResponse } from 'axios';
@@ -126,8 +112,8 @@ const agent = {
export default agent; export default agent;
``` ```
# Creating `CityDropdown` Component ## Creating `CityDropdown` Component
📂 Suggested Folder: shared/api/ 📂 Suggested Folder: features/city/
- [ ] Create components for the parts of the UI you need - [ ] Create components for the parts of the UI you need
```ts ```ts
@@ -163,8 +149,8 @@ const CityDropdown = () => {
export default CityDropdown; export default CityDropdown;
``` ```
## **See the analysis of `CityDropdown` component code in the additional info** - [ ] **See the analysis of `CityDropdown` component code in the additional info**
# Creating `transportationCard` Component ## Creating `transportationCard` Component
```ts ```ts
import { TransportationSearchResult } from "@/shared/models/transportation/transportationSearchResult"; import { TransportationSearchResult } from "@/shared/models/transportation/transportationSearchResult";
import React from "react"; import React from "react";
@@ -220,479 +206,16 @@ const TransportationCard: React.FC<Props> = ({ transportation }) => {
export default TransportationCard; export default TransportationCard;
``` ```
# Creating `transportationSearchForm` Component ## Creating `transportationSearchForm` Component
See the code from: See the code from:
https://github.com/MehrdadShirvani/AlibabaClone-Frontend/tree/develop/alibabaclone-frontend/src/features/transportation https://github.com/MehrdadShirvani/AlibabaClone-Frontend/tree/develop/alibabaclone-frontend/src/features/transportation
# Additional Notes:
## What is vite
## What is CORS?
### CORS (Cross-Origin Resource Sharing)
**What it is:** CORS is a browser security feature that blocks requests to a different domain unless explicitly allowed by the server.
### 🔐 What is CORS **really** for?
CORS is **not** about protecting the backend server.
It’s about **protecting users** from **malicious websites** using their browser as a weapon.
---
### 🧠 Imagine this attack:
You’re logged into your **bank** in one browser tab (`bank.com`).
Now, you visit a shady website in another tab (`evil.com`). That site has JavaScript that tries to send this:
```js
fetch('https://bank.com/api/transfer?amount=5000&to=hacker', {
credentials: 'include' // it sends your bank cookies!
});
```
➡️ If the browser allowed this freely, the request would go through **using your login session**, and you’d lose money.
---
### 💥 Enter CORS
So the browser says:
> “Hold on. This JavaScript is from `evil.com`, and it’s trying to talk to `bank.com`. I won’t let that happen **unless `bank.com` says it’s okay**.”
That’s why the **backend server** must respond with something like:
```http
Access-Control-Allow-Origin: https://mytrusteddomain.com
```
Only then will the browser say, “Okay, go ahead.”
---
### So the purpose of CORS is:
✅ To **restrict browsers** from sending or accepting responses from **cross-origin** sources
❌ Not to protect the backend
❌ Not to restrict Postman, curl, servers, or mobile apps
---
### 🔄 In Dev Work (like your React + API case):
- You’re running React at `http://localhost:5173`
- You’re running ASP.NET Core API at `https://localhost:7001`
- The browser sees this as two **different origins** → blocks the request unless CORS is enabled on the API.
---
### 🧪 Why Postman works:
- Postman isn’t a browser
- Postman doesn’t care about same-origin policy
- Postman just sends requests like your backend would
---
### ✅ Conclusion:
- **CORS is a browser feature to protect users**
- **It restricts frontend JavaScript from calling other domains unless explicitly allowed**
- **You must configure your server to say “Yes, I allow your frontend to talk to me”**
## Feature-based Folder Structure
## Explanation of the `agent.ts`
## React.FC
### In your code:
```tsx
const TransportationCard: React.FC<Props> = ({ transportation }) => { ... }
```
You're using `React.FC<Props>`.
✅ `FC` stands for **Function Component**.
---
### So what is `React.FC` exactly?
- `React.FC` (or `React.FunctionComponent`) is a **TypeScript type** that you can use to type your functional React components.
- It **tells TypeScript** that:
- This component is a function
- It **receives props** (in your case, `Props`)
- It **returns JSX** (it returns something React can render)
---
### Why use it?
Here’s what you get when you use `React.FC`:
1. ✅ **Prop typing** — You get auto-complete and error checking for props.
2. ✅ **Children** are automatically included. (More on this below.)
3. ✅ **Cleaner code** because TypeScript understands the shape of the component.
---
### Without `React.FC`
You could just write:
```tsx
const TransportationCard = ({ transportation }: Props) => { ... }
```
and it would work!
But you lose some "extra typing safety" like automatic `children` typing.
---
### Small Detail: `children`
When you use `React.FC`, **TypeScript automatically** allows your component to accept `children` too — even if you didn’t define it in your `Props`.
For example:
```tsx
<TransportationCard transportation={t}>
<p>Hello</p> // This would be valid automatically
</TransportationCard>
```
Because `children` is **always** part of a `React.FC`.
👉 If you **don't** use `React.FC`, and you want to accept `children`, you have to **manually** add it to your props.
---
### Some developers today...
**Some people** (even in big companies) prefer **NOT** to use `React.FC` anymore because:
- It **forces children** even when you don’t want children.
- It's **a little bit redundant** — you can already just type props without it.
> So in modern codebases, **both styles are OK** — it’s just a preference.
---
### Quick Summary:
|Using `React.FC`|Not using `React.FC`|
|:--|:--|
|Good for simple, typed functional components|Good if you want full manual control over props|
|Auto-includes `children` prop|You must manually add `children` if needed|
|Easy and quick|More customizable|
---
---
## `CityDropdown` Component:
### 1. **State Variables**
```tsx
const [cities, setCities] = useState<City[]>([]);
const [selectedCity, setSelectedCity] = useState<number | undefined>();
```
- `cities`: holds the list of cities retrieved from the backend (starts empty `[]`).
- `selectedCity`: holds the currently selected city’s ID (`number`) or `undefined` if nothing is selected yet.
---
### 2. **Fetching Cities on Mount**
```tsx
useEffect(() => {
agent.Cities.list()
.then(setCities)
.catch((err) => console.error("error loading cities", err));
}, []);
```
- When the component **mounts** (`[]` dependency array = run once), it calls `agent.Cities.list()`.
- `agent.Cities.list()` presumably returns a promise that resolves to an array of `City` objects.
- On success → `setCities` updates the `cities` state.
- On failure → logs an error to the console.
---
### 3. **Rendering the Dropdown**
```tsx
<select
value={selectedCity}
onChange={(e) => setSelectedCity(Number(e.target.value))}
>
<option value="">Select a City</option>
{cities.map((city) => (
<option key={city.id} value={city.id}>
{city.title}
</option>
))}
</select>
```
- Renders a `<select>` (dropdown).
- Its value is bound to `selectedCity`.
- When the user changes the selection (`onChange`), it updates `selectedCity` by converting the selected `value` from a string to a number (`Number(e.target.value)`).
- The dropdown always starts with a placeholder option: **"Select a City"**.
- It dynamically creates an `<option>` for each city in the `cities` array:
- `key` and `value` are the city's `id`.
- Displayed text is the city's `title`.
---
### What is `useEffect`?
🔹 **`useEffect` is a React Hook**.
It **tells React to run some code after the component renders**.
Think of it like:
- _"Hey React, when this component shows up on the screen, please also run this function!"_
In your code:
```tsx
useEffect(() => {
agent.Cities.list()
.then(setCities)
.catch((err) => console.error("error loading cities", err));
}, []);
```
- This function (`() => { ... }`) **runs right after** the component is first shown (because of `[]` — the empty array).
- Inside it, you are **calling your API** (`agent.Cities.list()`) to get the cities.
- When the server **responds with a list of cities**, you **save** them into your component's memory (state) by calling `setCities(data)`.
---
### What is `useState`?
🔹 **`useState` is another React Hook**.
It **creates a piece of memory** for your component.
In your code:
```tsx
const [cities, setCities] = useState<City[]>([]);
const [selectedCity, setSelectedCity] = useState<number | undefined>();
```
Here’s what is happening:
- `cities` is a variable that starts as an **empty array** (`[]`).
- `setCities` is a **function** you use to **change** the value of `cities`.
Same with `selectedCity`:
- `selectedCity` starts as `undefined` (nothing selected yet).
- `setSelectedCity` lets you **update** which city is selected.
---
**Simple analogy:**
Imagine your component is a whiteboard.
- `useState` gives you a small _erasable box_ on the board.
- You can write something there (`cities`, `selectedCity`).
- If you want to change what’s written, you use the special pen `setCities` or `setSelectedCity`, **not your finger** (so React knows it changed and redraws the screen if needed).
---
## `TransportationCard` Component
### 1. **The Component Function**
```tsx
const TransportationCard: React.FC<Props> = ({ transportation }) => {
```
- This is a **React Functional Component**.
- It takes `transportation` from props (destructured directly).
- It **returns JSX** that shows the transportation info in a styled card.
---
### 2. **Inside the JSX**
#### 2.1 Left Side — Price and Button
```tsx
<div className="flex flex-col items-center">
<div className="text-blue-600 font-bold text-lg">
{transportation.price} Toman
</div>
<button className="bg-blue-500 text-white px-4 py-2 rounded-md mt-2 hover:bg-blue-600">
Select Ticket
</button>
</div>
```
- Shows the **price** (`price` field) styled with blue, bold text.
- Has a **Select Ticket** button — blue, rounded, changes shade on hover.
---
#### 2.2 Middle — Trip Info
```tsx
<div className="flex-1 mx-4 text-center">
<div className="font-semibold text-gray-700">
{transportation.companyTitle}
</div>
<div className="flex items-center justify-center mt-2">
<div className="mx-2">{transportation.fromCityTitle}</div>
<span className="text-gray-400">→</span>
<div className="mx-2">{transportation.toCityTitle}</div>
</div>
<div className="text-sm text-gray-500 mt-1">
{new Date(transportation.startDateTime).toLocaleDateString("en", {
hour: "2-digit",
minute: "2-digit",
})}
</div>
</div>
```
- Shows the **company name**.
- Shows **From → To** cities in a neat way with an arrow (`→`) between them.
- Shows the **departure time**:
- `startDateTime` is parsed using `new Date(...)`.
- `toLocaleDateString("en", { hour: "2-digit", minute: "2-digit" })` formats it to show just **hours and minutes**.
---
#### 2.3 Right Side — Company Logo
```tsx
<div className="w-12 h-12">
<img
src="/images/company-placeholder.png"
alt="company"
className="w-full h-full object-contain"
/>
</div>
```
- Displays a small company **logo image** (placeholder image for now).
- `object-contain` keeps the image inside the box without stretching.
## `TrasnportationSearchForm` Component
### 🧠 Main Concepts Used:
| Feature | Purpose |
| :------------------------ | :--------------------------------------------------------------------------- |
| `useState` | To **store and manage** the form inputs, cities, results, and loading status |
| `useEffect` | To **load the list of cities once** when the component appears |
| **Typing with models** | `City`, `TransportationSearchRequest`, `TransportationSearchResult` |
| **Event handling** | To update form values and trigger the search |
| **Conditional rendering** | Show "Loading", "No results", or "Results" dynamically |
---
### 📦 Let's break down the code:
#### 1. ✍️ States
```tsx
const [searchResults, setSearchResults] = useState<TransportationSearchResult[]>([]);
const [loading, setLoading] = useState(false);
const [cities, setCities] = useState<City[]>([]);
const [form, setForm] = useState<TransportationSearchRequest>({
fromCityId: undefined,
toCityId: undefined,
startDate: null,
endDate: null,
vehicleTypeId: undefined,
});
```
You define **4 states**:
- `searchResults`: List of found transportations
- `loading`: True/false if waiting for API
- `cities`: List of available cities
- `form`: The form input values the user is selecting
All typed properly ✅
---
#### 2. 📡 Fetch cities automatically (useEffect)
```tsx
useEffect(() => {
agent.Cities.list().then(setCities);
}, []);
```
**Meaning**:
- When the page **first loads**, it **calls the API** to get cities.
- `agent.Cities.list()` calls your backend, and when it gets the cities, it puts them into `cities` state.
- The empty `[]` **dependency array** means this happens **only once**, not every time anything changes.
👉 This is why your cities `<select>` dropdown fills up!
---
#### 3. ✏️ Handle input changes
```tsx
const handleChange = (e: React.ChangeEvent<HTMLSelectElement | HTMLInputElement>) => { ... }
```
Whenever a user types/selects:
- You detect **which field** (`name`) and **what value** (`value`) they changed
- Update the `form` state accordingly:
- `fromCityId` and `toCityId` are converted to numbers (`parseInt`)
- `startDate` and `endDate` allow null
- Other fields (if any) are copied directly
---
#### 4. 🔍 Handle Search button
```tsx
const handleSearch = () => { ... }
```
When the user clicks **Search**:
- Set `loading` to `true`
- Call the backend API `agent.TransportationSearch.search(form)`
- When the result comes back:
- Save it into `searchResults`
- If error: log it
- Finally, set `loading` to `false` again
---
#### 5. 🖥️ Return (render) JSX
You build a UI:
- **Vehicle Types** (Bus, Train, Airplane) selectable with a click → sets `vehicleTypeId`
- **From City** and **To City** dropdowns
- **Start and End Date** inputs
- **Search Button** to trigger the search
- **Result area** that shows:
- If loading: "Loading..."
- If no results: "No results found"
- If results: List of `TransportationCard` components for each found item.
---
# 🧠 Hints & Notes
# 🙌 Acknowledgements
- ChatGPT for snippet refinement and explanations
# 🔍 References
- [ ] Check out [[Session05 Additional Info]]
- [ ] Watch for [React](https://www.youtube.com/watch?v=SqcY0GlETPk&ab_channel=ProgrammingwithMosh)