added checksum to note_attachment

db/migrations/0213__note_attachments.sql

@@ -5,6 +5,7 @@ CREATE TABLE IF NOT EXISTS "note_attachments"
     name         TEXT not null,
     mime         TEXT not null,
     isProtected    INT  not null DEFAULT 0,
+    contentCheckSum    TEXT not null,
     utcDateModified TEXT not null,
     isDeleted    INT  not null,
     `deleteId`    TEXT DEFAULT NULL);

src/becca/entities/bnote.js

@@ -1442,17 +1442,22 @@ class BNote extends AbstractBeccaEntity {
      * @returns {BNoteAttachment}
      */
     saveNoteAttachment(name, mime, content) {
-        this.getNoteAttachments()
+        let noteAttachment = this.getNoteAttachmentByName(name);
 
-        const noteAttachment = new BNoteAttachment({
+        if (noteAttachment
+            && noteAttachment.mime === mime
+            && noteAttachment.contentCheckSum === noteAttachment.calculateCheckSum(content)) {
+
+            return noteAttachment; // no change
+        }
+
+        noteAttachment = new BNoteAttachment({
             noteId: this.noteId,
             name,
             mime,
             isProtected: this.isProtected
         });
 
-        noteAttachment.save();
-
         noteAttachment.setContent(content);
 
         return noteAttachment;

src/becca/entities/bnote_attachment.js

@@ -33,6 +33,8 @@ class BNoteAttachment extends AbstractBeccaEntity {
         /** @type {boolean} */
         this.isProtected = !!row.isProtected;
         /** @type {string} */
+        this.contentCheckSum = row.contentCheckSum;
+        /** @type {string} */
         this.utcDateModified = row.utcDateModified;
     }
 
@@ -97,18 +99,22 @@ class BNoteAttachment extends AbstractBeccaEntity {
 
         sql.upsert("note_attachment_contents", "noteAttachmentId", pojo);
 
-        const hash = utils.hash(`${this.noteAttachmentId}|${pojo.content.toString()}`);
+        this.contentCheckSum = this.calculateCheckSum(pojo.content);
 
         entityChangesService.addEntityChange({
             entityName: 'note_attachment_contents',
             entityId: this.noteAttachmentId,
-            hash: hash,
+            hash: this.contentCheckSum,
             isErased: false,
             utcDateChanged: this.getUtcDateChanged(),
             isSynced: true
         });
     }
 
+    calculateCheckSum(content) {
+        return utils.hash(`${this.noteAttachmentId}|${content.toString()}`);
+    }
+
     beforeSaving() {
         if (!this.name.match(/^[a-z0-9]+$/i)) {
             throw new Error(`Name must be alphanumerical, "${this.name}" given.`);