indexeddb: add checkBlobSupport() (#8804)

Add support to the indexeddb adapter for browsers which do not support storing
blobs directly in IndexedDB.

In current webkit, this error is seen as:

> Error [DataCloneError]: Failed to store record in an IDBObjectStore: BlobURLs are not yet supported.

Closes #8803

Author: alxndrsn

packages/node_modules/pouchdb-adapter-idb/src/index.js

@@ -15,7 +15,7 @@ import {
 
 import idbBulkDocs from './bulkDocs';
 import idbAllDocs from './allDocs';
-import checkBlobSupport from './blobSupport';
+import { checkBlobSupport } from 'pouchdb-adapter-utils';
 import countDocs from './countDocs';
 import {
   MISSING_DOC,
@@ -783,7 +783,7 @@ function init(api, opts, callback) {
     //
     if (!blobSupportPromise) {
       // make sure blob support is only checked once
-      blobSupportPromise = checkBlobSupport(txn);
+      blobSupportPromise = checkBlobSupport(txn, DETECT_BLOB_SUPPORT_STORE, 'key');
     }
 
     blobSupportPromise.then(function (val) {

packages/node_modules/pouchdb-adapter-indexeddb/src/allDocs.js

@@ -134,7 +134,8 @@ export default function (txn, metadata, opts, callback) {
     }
     if (opts.attachments && docData._attachments) {
       for (var name in docData._attachments) {
-        processing.push(processAttachment(name, doc, row.doc, opts.binary));
+        processing.push(processAttachment(name, doc, row.doc, opts.binary,
+            metadata.idb_attachment_format));
       }
     }
   }

packages/node_modules/pouchdb-adapter-indexeddb/src/bulkDocs.js

@@ -10,7 +10,9 @@ import {
 } from 'pouchdb-errors';
 
 import {
-  binaryStringToBlobOrBuffer as binStringToBlobOrBuffer
+  atob,
+  binaryStringToBlobOrBuffer as binStringToBlobOrBuffer,
+  blobOrBufferToBase64 as blufferToBase64,
 } from 'pouchdb-binary-utils';
 
 import { parseDoc } from 'pouchdb-adapter-utils';
@@ -322,9 +324,24 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
       } catch (e) {
         return Promise.reject(createError(BAD_ARG, 'Attachment is not a valid base64 string'));
       }
-      attachment.data = binStringToBlobOrBuffer(binData, attachment.content_type);
+      if (metadata.idb_attachment_format === 'binary') {
+        attachment.data = binStringToBlobOrBuffer(binData, attachment.content_type);
+      }
     } else {
       binData = attachment.data;
+      if (metadata.idb_attachment_format === 'base64') {
+        // TODO could run these in parallel, if we cared
+        return new Promise(resolve => {
+          blufferToBase64(attachment.data, function (b64) {
+            attachment.data = b64;
+            md5(binData, function (result) {
+              attachment.digest = 'md5-' + result;
+              attachment.length = binData.size || binData.length || 0;
+              resolve(attachment);
+            });
+          });
+        });
+      }
     }
 
     return new Promise(function (resolve) {

packages/node_modules/pouchdb-adapter-indexeddb/src/changes.js

@@ -72,7 +72,7 @@ export default function (txn, idbChanges, api, dbOpts, opts) {
       if (opts.include_docs && opts.attachments && doc.data._attachments) {
         var promises = [];
         for (var name in doc.data._attachments) {
-          var p = processAttachment(name, doc, change.doc, opts.binary);
+          var p = processAttachment(name, doc, change.doc, opts.binary, api.blobSupport);
           // We add the processing promise to 2 arrays, one tracks all
           // the promises needed before we fire onChange, the other
           // ensure we process all attachments before onComplete

packages/node_modules/pouchdb-adapter-indexeddb/src/getAttachment.js

@@ -1,11 +1,24 @@
 'use strict';
 
-import { btoa, readAsBinaryString } from 'pouchdb-binary-utils';
+import {
+  base64StringToBlobOrBuffer as b64StringToBluffer,
+  btoa,
+  readAsBinaryString,
+} from 'pouchdb-binary-utils';
 
 export default function getAttachment(docId, attachId, attachment, opts, cb) {
   const doc = opts.metadata;
   const data = doc.attachments[attachment.digest].data;
 
+  if (typeof data === 'string') {
+    if (opts.binary) {
+      cb(null, b64StringToBluffer(data, attachment.content_type));
+    } else {
+      cb(null, data);
+    }
+    return;
+  }
+
   if (opts.binary) {
     return cb(null, data);
   } else {

packages/node_modules/pouchdb-adapter-indexeddb/src/setup.js

@@ -2,6 +2,8 @@
 
 import { uuid } from 'pouchdb-utils';
 
+import { checkBlobSupport }  from 'pouchdb-adapter-utils';
+
 import { META_STORE, DOC_STORE, rawIndexFields, naturalIndexName, correctIndexFields } from './util';
 
 //
@@ -193,7 +195,21 @@ function openDatabase(openDatabases, api, opts, resolve, reject) {
         metadata.db_uuid = uuid();
       }
 
-      if (changed) {
+      if (!('idb_attachment_format' in metadata)) {
+        // There will be trouble if any browser _stops_ supporting blobs.
+
+        const createBlobDoc = blob => ({ id:'blob-support', blob });
+
+        checkBlobSupport(txn, META_STORE, createBlobDoc).then(blobSupport => {
+          // Unfortunate that we have to track this in both the metadata and on
+          // api, but sometimes we have access to one, sometimes the other (and
+          // sometimes both).  We could change function signatures in index.js
+          // to make this consistent.
+          api.blobSupport = metadata.idb_attachment_format = blobSupport ? 'binary' : 'base64';
+          metaStore.put(metadata);
+        });
+      } else if (changed) {
+        api.blobSupport = metadata.idb_attachment_format;
         metaStore.put(metadata);
       }
     };

packages/node_modules/pouchdb-adapter-indexeddb/src/util.js

@@ -1,7 +1,11 @@
 'use strict';
 
 import { createError, IDB_ERROR } from 'pouchdb-errors';
-import { btoa, readAsBinaryString } from 'pouchdb-binary-utils';
+import {
+  base64StringToBlobOrBuffer as b64StringToBluffer,
+  btoa,
+  readAsBinaryString,
+} from 'pouchdb-binary-utils';
 import { sanitise } from './rewrite';
 
 var DOC_STORE = 'docs';
@@ -17,10 +21,22 @@ function idbError(callback) {
   };
 }
 
-function processAttachment(name, src, doc, isBinary) {
+function processAttachment(name, src, doc, isBinary, attachmentFormat) {
 
   delete doc._attachments[name].stub;
 
+  if (attachmentFormat === 'base64') {
+    if (isBinary) {
+      const att = src.attachments[doc._attachments[name].digest];
+      doc._attachments[name].data = b64StringToBluffer(att.data, att.content_type);
+    } else {
+      doc._attachments[name].data =
+        src.attachments[doc._attachments[name].digest].data;
+    }
+    delete doc._attachments[name].length;
+    return Promise.resolve();
+  }
+
   if (isBinary) {
     doc._attachments[name].data =
       src.attachments[doc._attachments[name].digest].data;

…s/pouchdb-adapter-idb/src/blobSupport.js …db-adapter-utils/src/checkBlobSupport.jspackages/node_modules/pouchdb-adapter-idb/src/blobSupport.js renamed to packages/node_modules/pouchdb-adapter-utils/src/checkBlobSupport.js packages/node_modules/pouchdb-adapter-idb/src/blobSupport.js renamed to packages/node_modules/pouchdb-adapter-utils/src/checkBlobSupport.js

@@ -1,9 +1,12 @@
 import { blob as createBlob } from 'pouchdb-binary-utils';
-import { DETECT_BLOB_SUPPORT_STORE } from './constants';
 
 //
 // Blobs are not supported in all versions of IndexedDB, notably
-// Chrome <37 and Android <5. In those versions, storing a blob will throw.
+// Chrome <37, Android <5 and (some?) webkit-based browsers.
+// In those versions, storing a blob will throw.
+//
+// Example Webkit error:
+// > DataCloneError: Failed to store record in an IDBObjectStore: BlobURLs are not yet supported.
 //
 // Various other blob bugs exist in Chrome v37-42 (inclusive).
 // Detecting them is expensive and confusing to users, and Chrome 37-42
@@ -13,10 +16,21 @@ import { DETECT_BLOB_SUPPORT_STORE } from './constants';
 // 404 bug: https://code.google.com/p/chromium/issues/detail?id=447916
 // FileReader bug: https://code.google.com/p/chromium/issues/detail?id=447836
 //
-function checkBlobSupport(txn) {
+function checkBlobSupport(txn, store, docIdOrCreateDoc) {
   return new Promise(function (resolve) {
     var blob = createBlob(['']);
-    var req = txn.objectStore(DETECT_BLOB_SUPPORT_STORE).put(blob, 'key');
+
+    let req;
+    if (typeof docIdOrCreateDoc === 'function') {
+      // Store may require a specific key path, in which case we can't store the
+      // blob directly in the store.
+      const createDoc = docIdOrCreateDoc;
+      const doc = createDoc(blob);
+      req = txn.objectStore(store).put(doc);
+    } else {
+      const docId = docIdOrCreateDoc;
+      req = txn.objectStore(store).put(blob, docId);
+    }
 
     req.onsuccess = function () {
       var matchedChrome = navigator.userAgent.match(/Chrome\/(\d+)/);

packages/node_modules/pouchdb-adapter-utils/src/index.js

@@ -1,4 +1,5 @@
 import allDocsKeysQuery from './allDocsKeysQuery';
+import checkBlobSupport from './checkBlobSupport';
 import parseDoc from './parseDoc';
 import {
   invalidIdError,
@@ -12,6 +13,7 @@ import updateDoc from './updateDoc';
 
 export {
   allDocsKeysQuery,
+  checkBlobSupport,
   invalidIdError,
   isDeleted,
   isLocalId,