Implement attachment download

src/controllers/attachment.js

@@ -56,9 +56,16 @@ const deleteAttachment = async (req, res) => {
   res.status(204).end()
 }
 
+const downloadAttachment = async (req, res) => {
+  const { id } = req.params
+  const attachment = await attachmentService.downloadAttachment(id, res)
+  res.status(201).json(attachment)
+}
+
 module.exports = {
   getAttachments,
   createAttachments,
   updateAttachment,
-  deleteAttachment
+  deleteAttachment,
+  downloadAttachment
 }

src/routes/attachment.js

@@ -17,6 +17,7 @@ router.use(restrictTo(TUTOR))
 router.param('id', idValidation)
 
 router.get('/', asyncWrapper(attachmentController.getAttachments))
+router.get('/:id', asyncWrapper(attachmentController.downloadAttachment))
 router.post('/', upload.array('files'), asyncWrapper(attachmentController.createAttachments))
 router.patch('/:id', isEntityValid({ params }), asyncWrapper(attachmentController.updateAttachment))
 router.delete('/:id', isEntityValid({ params }), asyncWrapper(attachmentController.deleteAttachment))

src/services/attachment.js

@@ -77,6 +77,19 @@ const attachmentService = {
     }
 
     await Attachment.findByIdAndRemove(id).exec()
+  },
+
+  downloadAttachment: async (id, res) => {
+    const attachment = await Attachment.findById(id).exec()
+
+    if (!attachment) {
+      throw createError(404, DOCUMENT_NOT_FOUND('Attachment'))
+    }
+
+    res.setHeader('Content-Disposition', `attachment; filename="${attachment.fileName}"`)
+    res.setHeader('Content-Type', 'application/octet-stream')
+
+    return await uploadService.downloadFile(attachment.link, ATTACHMENT, res)
   }
 }
 

src/services/upload.js

@@ -67,6 +67,20 @@ const uploadService = {
         resolve(res)
       })
     ).catch((e) => e.message)
+  },
+
+  downloadFile: (fileName, containerName, res) => {
+    blobService = azureStorage.createBlobService(STORAGE_ACCOUNT, ACCESS_KEY, AZURE_HOST)
+
+    return new Promise((resolve, reject) => {
+      blobService.getBlobToStream(containerName, fileName, res, (err) => {
+        if (err) {
+          reject(new Error('Download error'))
+        } else {
+          resolve()
+        }
+      })
+    })
   }
 }
 

src/test/integration/controllers/attachments.spec.js

@@ -5,6 +5,7 @@ const { UNAUTHORIZED, FORBIDDEN, DOCUMENT_NOT_FOUND } = require('~/consts/errors
 const TokenService = require('~/services/token')
 const Attachment = require('~/models/attachment')
 const uploadService = require('~/services/upload')
+const attachmentService = require('~/services/attachment')
 
 const {
   enums: { RESOURCES_TYPES_ENUM }
@@ -298,3 +299,63 @@ describe('Attachments controller', () => {
     })
   })
 })
+
+describe('downloadAttachment', () => {
+  jest.mock('~/models/attachment')
+  jest.mock('~/services/upload')
+  const ATTACHMENT = 'attachment'
+
+  afterEach(() => {
+    jest.clearAllMocks()
+  })
+
+  beforeAll(() => {
+    uploadService.downloadFile = jest.fn()
+  })
+
+  it('should download the attachment successfully when it exists', async () => {
+    const attachmentId = 'testId'
+    const attachment = {
+      _id: attachmentId,
+      fileName: 'testFile.txt',
+      link: 'https://example.com/testFile.txt'
+    }
+
+    const responseMock = {
+      setHeader: jest.fn()
+    }
+
+    jest.spyOn(Attachment, 'findById').mockReturnValue({
+      exec: jest.fn().mockResolvedValue(attachment)
+    })
+    uploadService.downloadFile.mockResolvedValue()
+
+    await expect(attachmentService.downloadAttachment(attachmentId, responseMock)).resolves.toBeUndefined()
+
+    expect(Attachment.findById).toHaveBeenCalledWith(attachmentId)
+    expect(responseMock.setHeader).toHaveBeenCalledWith(
+      'Content-Disposition',
+      `attachment; filename="${attachment.fileName}"`
+    )
+    expect(responseMock.setHeader).toHaveBeenCalledWith('Content-Type', 'application/octet-stream')
+    expect(uploadService.downloadFile).toHaveBeenCalledWith(attachment.link, ATTACHMENT, responseMock)
+  })
+
+  it('should throw a 404 error if the attachment is not found', async () => {
+    const attachmentId = 'nonExistentId'
+    const responseMock = {
+      setHeader: jest.fn()
+    }
+
+    jest.spyOn(Attachment, 'findById').mockReturnValue({
+      exec: jest.fn().mockResolvedValue(null)
+    })
+
+    await expect(attachmentService.downloadAttachment(attachmentId, responseMock)).rejects.toThrow(
+      'Attachment with the specified IDs were not found.'
+    )
+    expect(Attachment.findById).toHaveBeenCalledWith(attachmentId)
+    expect(responseMock.setHeader).not.toHaveBeenCalled()
+    expect(uploadService.downloadFile).not.toHaveBeenCalled()
+  })
+})

src/test/unit/services/upload.spec.js

@@ -28,7 +28,7 @@ const getBlobPropertiesStatusWithError = (container, blobName, cb) => {
 }
 
 const file = {
-  buffer: 'data:image/jpeg;base64,/9j/4AAQSkZJRgABAgAAAQABAAD...',
+  buffer: 'data:image/jpegbase64,/9j/4AAQSkZJRgABAgAAAQABAAD...',
   name: 'example.jpg',
   newName: 'exampleName.jpg'
 }
@@ -122,3 +122,51 @@ describe('uploadService', () => {
     }
   })
 })
+
+describe('downloadFile', () => {
+  jest.mock('azure-storage', () => ({
+    createBlobService: jest.fn()
+  }))
+
+  let blobServiceMock
+
+  beforeEach(() => {
+    blobServiceMock = {
+      getBlobToStream: jest.fn()
+    }
+    azureStorage.createBlobService.mockReturnValue(blobServiceMock)
+  })
+
+  afterEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it('should resolve if the blob is downloaded successfully', async () => {
+    const fileName = 'testFile.txt'
+    const containerName = 'test-container'
+    const responseMock = jest.fn()
+
+    blobServiceMock.getBlobToStream.mockImplementation((container, file, res, callback) => {
+      callback(null)
+    })
+
+    await expect(uploadService.downloadFile(fileName, containerName, responseMock)).resolves.toBeUndefined()
+    expect(azureStorage.createBlobService).toHaveBeenCalled()
+    expect(blobServiceMock.getBlobToStream).toHaveBeenCalled()
+  })
+
+  it('should reject if there is an error downloading the blob', async () => {
+    const fileName = 'testFile.txt'
+    const containerName = 'test-container'
+    const responseMock = jest.fn()
+    const error = new Error('Download error')
+
+    blobServiceMock.getBlobToStream.mockImplementation((container, file, res, callback) => {
+      callback(error)
+    })
+
+    await expect(uploadService.downloadFile(fileName, containerName, responseMock)).rejects.toThrow('Download error')
+    expect(azureStorage.createBlobService).toHaveBeenCalled()
+    expect(blobServiceMock.getBlobToStream).toHaveBeenCalled()
+  })
+})