# Fetch to Axios Migration Guide

This document outlines the pattern for migrating fetch API calls to axios in our codebase.

## Why migrate from fetch to axios?

Axios provides several advantages over the native fetch API:
- Automatic JSON data transformation
- Better error handling
- Request/response interceptors 
- Simpler syntax for common operations
- Consistent error objects

## Migration Pattern

### 1. Import axios

First, add the axios import to your file:

```typescript
import axios from 'axios';
```

### 2. Replace GET requests

**Before (with fetch):**
```typescript
const response = await fetch(url, {
  method: 'GET',
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  mode: 'cors',
  credentials: 'include' // or 'omit'
});

if (!response.ok) {
  const errorText = await response.text();
  throw new Error(`Failed: ${response.status} ${response.statusText}`);
}

const data = await response.json();
return data;
```

**After (with axios):**
```typescript
const response = await axios.get(url, {
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  withCredentials: true // replaces credentials: 'include'
  // Note: 'mode: cors' is not needed with axios
});

// No need to check response.ok - axios throws on error status codes
// No need to parse JSON - axios does this automatically
return response.data;
```

### 3. Replace POST requests

**Before (with fetch):**
```typescript
const response = await fetch(url, {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  body: JSON.stringify(data),
  mode: 'cors',
  credentials: 'include' // or 'omit'
});

if (!response.ok) {
  throw new Error(`Failed: ${response.status} ${response.statusText}`);
}

const responseData = await response.json();
return responseData;
```

**After (with axios):**
```typescript
const response = await axios.post(url, data, {
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  withCredentials: true // if needed
});

return response.data;
```

### 4. Replace PUT requests

**Before (with fetch):**
```typescript
const response = await fetch(url, {
  method: 'PUT',
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  body: JSON.stringify(data),
  mode: 'cors',
  credentials: 'include' // or 'omit'
});

if (!response.ok) {
  throw new Error(`Failed: ${response.status} ${response.statusText}`);
}

const responseData = await response.json();
return responseData;
```

**After (with axios):**
```typescript
const response = await axios.put(url, data, {
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  withCredentials: true // if needed
});

return response.data;
```

### 5. Replace DELETE requests

**Before (with fetch):**
```typescript
const response = await fetch(url, {
  method: 'DELETE',
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  mode: 'cors',
  credentials: 'include' // or 'omit'
});

if (!response.ok) {
  throw new Error(`Failed: ${response.status} ${response.statusText}`);
}

// Handle response as needed
```

**After (with axios):**
```typescript
const response = await axios.delete(url, {
  headers: {
    'Content-Type': 'application/json',
    // other headers...
  },
  withCredentials: true // if needed
});

// response.data is already parsed if JSON was returned
```

### 6. Error Handling

**Before (with fetch):**
```typescript
try {
  const response = await fetch(url);
  if (!response.ok) {
    const errorText = await response.text();
    console.error(`API error: ${response.status} ${response.statusText}`, errorText);
    throw new Error(`Failed: ${response.status} ${response.statusText}`);
  }
  const data = await response.json();
  return data;
} catch (error) {
  console.error('Request failed:', error);
  throw error;
}
```

**After (with axios):**
```typescript
try {
  const response = await axios.get(url);
  return response.data;
} catch (error) {
  if (axios.isAxiosError(error)) {
    console.error('API error:', error.message);
    console.error('Status:', error.response?.status);
    console.error('Data:', error.response?.data);
    
    throw new Error(`API Error: ${error.response?.status} ${error.message}`);
  }
  console.error('Request failed:', error);
  throw error;
}
```

## Common Patterns by File Type

### Service Files

For service files, follow this general pattern:

```typescript
import axios from 'axios';
import { API_BASE_URL } from '@/config';

export const exampleService = {
  getAll: async () => {
    try {
      const response = await axios.get(`${API_BASE_URL}/api/resource`, {
        headers: {
          'Content-Type': 'application/json',
        },
        withCredentials: false
      });

      return response.data;
    } catch (error) {
      console.error('Error:', error);
      return []; // or throw error depending on your error handling strategy
    }
  },
  
  getById: async (id) => {
    try {
      const response = await axios.get(`${API_BASE_URL}/api/resource/${id}`);
      return response.data;
    } catch (error) {
      console.error(`Error fetching resource ${id}:`, error);
      throw error;
    }
  },
  
  create: async (data) => {
    try {
      const response = await axios.post(`${API_BASE_URL}/api/resource`, data);
      return response.data;
    } catch (error) {
      console.error('Error creating resource:', error);
      throw error;
    }
  }
  
  // etc.
};
```

### Component Files

For component files, integrate axios calls as follows:

```typescript
import axios from 'axios';
import { API_BASE_URL } from '@/config';

const YourComponent = () => {
  useEffect(() => {
    const fetchData = async () => {
      try {
        const response = await axios.get(`${API_BASE_URL}/api/resource`);
        setData(response.data);
      } catch (error) {
        console.error('Error fetching data:', error);
        setError('Failed to load data');
      } finally {
        setLoading(false);
      }
    };
    
    fetchData();
  }, []);
  
  // rest of component
};
```

## Remaining Files to Update

Based on our analysis, these files need to be updated:

- src/pages/project-detail.tsx
- src/pages/project-edit.tsx
- src/pages/projects.tsx
- src/components/appraisal/AppraisalForm.tsx
- src/pages/appraisal/assessment-areas.tsx
- src/utils/create-indicators.js
- src/pages/appraisal/competencies.tsx
- src/pages/appraisal/cycles.tsx
- src/pages/appraisal/hr-remarks.tsx
- src/pages/appraisal/management-remarks.tsx
- src/pages/appraisal/manager-dashboard.tsx

Follow the patterns in this guide to update these files.