Opening a document from the Salesforce Database

1//snipped for brevity
2@AuraEnabled(Cacheable=true) 
3public static ContentVersionWrapper getFileDataFromId(String Id) {
4  try {
5    Long max = 1024 * 1024 * 15; // 25 MB
6    ContentVersion cv = [SELECT Title, FileExtension, ContentSize, ContentDocumentId, LastModifiedDate FROM ContentVersion WHERE Id = :Id];
7    ContentVersionWrapper cvw = new ContentVersionWrapper(cv);
8
9    if(cv.ContentSize < max) {
10      //Only query VersionData if size < 25 MB
11      ContentVersion cvData = [SELECT VersionData FROM ContentVersion WHERE Id = :Id];
12      cvw.body = EncodingUtil.base64Encode(cvData.VersionData);
13    }else{
14      //Set proxy url with Id
15      cvw.url = 'https://{proxy_url}/document/'+ Id;
16    }
17
18    return cvw;
19  } catch(Exception e) {
20      throw new AuraHandledException(e.getMessage());
21  }
22}
23
24//sample wrapper class
25public class ContentVersionWrapper {
26  @AuraEnabled
27  public String name {get; set;}
28  
29  @AuraEnabled
30  public String body { get; set; }
31  
32  @AuraEnabled
33  public String url { get; set; }
34
35  @AuraEnabled
36  public ContentVersion cv { get; set; }
37
38  public ContentVersionWrapper(ContentVersion contentVer) {
39    this.cv = contentVer;
40    this.name = contentVer.Title + '.' + contentVer.FileExtension;
41  }
42}

1// force-app/main/default/lwc/apryseWvInstance/ApryseWvInstance.js
2
3//snipped for brevity
4import { registerListener, unregisterAllListeners } from 'c/pubsub';
5
6connectedCallback() {
7  registerListener('blobSelected', this.handleBlobSelected, this);
8  //register other listeners here
9}
10
11disconnectedCallback() {
12  //unregister all listeners here
13}
14
15handleBlobSelected(record) {
16
17  const payload = {
18    blobOrUrl: null,
19    extension: record.cv.FileExtension,
20    filename: record.name,
21    documentId: record.cv.Id
22  };
23
24  // If the record has a URL, use the proxy server
25  if(record.url){
26    payload.blobOrUrl = record.url;
27  }else{
28  // Otherwise, convert the base64 body to a Blob
29    payload.blobOrUrl = new Blob([_base64ToArrayBuffer(record.body)], {
30      type: mimeTypes[record.cv.FileExtension]
31    });
32  }
33
34  this.iframeWindow.postMessage({type: 'OPEN_DOCUMENT_BLOB', payload} , '*');
35}

1//snipped for brevity
2window.addEventListener("message", receiveMessage, false);
3
4function receiveMessage(event) {
5  if (event.isTrusted && typeof event.data === 'object') {
6    switch (event.data.type) {
7      case 'OPEN_DOCUMENT_BLOB':
8        const { blobOrUrl, extension, filename, documentId } = event.data.payload;
9        instance.loadDocument(blobOrUrl, { extension, filename, documentId })
10        break;
11      default:
12        break;
13    }
14  }
15}

1//snipped for brevity
2const conn = new jsforce.Connection({ loginUrl: process.env.SF_LOGIN_URL });
3
4app.get('/document/:docId', async (req, res) => {
5    const docId = req.params.docId;
6
7    
8    // 1) Find the latest ContentVersion for the ContentDocument
9    const [ver] = await conn
10      .sobject("ContentVersion")
11      .find(
12        { Id: docId, IsLatest: true },
13        ["Id", "Title", "FileExtension"]
14      )
15      .limit(1);
16
17
18    const filename = `${ver.Title || ver.Id}.${ver.FileExtension || "bin"}`;
19    const contentType = resolveResponseType(req, filename);
20
21    // 2) Set headers and stream the blob from Salesforce to the client
22    res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
23    res.setHeader("Content-Type", contentType);
24
25    const sfStream = conn
26      .sobject("ContentVersion")
27      .record(ver.Id)
28      .blob("VersionData");
29
30    // Mirror SF Content-Length if provided
31    sfStream.on("response", (sfRes) => {
32      const len = sfRes.headers["content-length"];
33      if (len) res.setHeader("Content-Length", len);
34    });
35
36    sfStream.on("error", (e) => {
37      console.error("Salesforce stream error:", e);
38      if (!res.headersSent) res.status(502).send("Error streaming file from Salesforce");
39      else res.end();
40    });
41
42    sfStream.pipe(res);
43})