SBS: Personal document management system 08 - Delete Document

Copy this link when reproducing:
http://www.casperlee.com/en/y/blog/52

Just like before, let's take it easy and watch a video first. This video was shot by me last week at the Sea World in Shenzhen. And it is about a very beautiful show of a music fountain.

There is a main function that we have not implemented: Delete Document. Let's see how to do it in this section.

1. Open the main form in the main project, and double click on the "Delete" button to add an OnClick event handler function.

        private void btnDelete_Click(object sender, EventArgs e)
        {
            if (lvResult.SelectedItems.Count == 0)
            {
                return;
            }

            if (MessageBox.Show(
                this, 
                "Are you sure?", 
                "Confirm", 
                MessageBoxButtons.YesNo) == DialogResult.No)
            {
                return;
            }

            foreach (ListViewItem item in lvResult.SelectedItems)
            {
                ResourceEx rx = (ResourceEx)item.Tag;
                ResourceBll.Instance.DelResource(rx);
                lvResult.Items.Remove(item);
            }

            MessageBox.Show(this, "Done!");
        }

2. Open the file "ResourceBll.cs" in the Bll project and add a function "DelResource".

        public void DelResource(ResourceEx aResouce)
        {
            CreateHandler(true);
            handler.DelResource(aResouce);
        }

3. Here is the code of the "CreateHandler" function.

        private void CreateHandler(bool aSupportFulltextSearch)
        {
            if ((handler == null)
                || (handler is FulltextResourceHandler != aSupportFulltextSearch))
            {
                handler = aSupportFulltextSearch ? 
                    new FulltextResourceHandler() : new ResourceHandler();
            }
        }

4. Open the file "ResourceHandler.cs" in the Bll project and add a function "DelResource".

        public virtual void DelResource(ResourceEx aResource)
        {
            using (ResourceManageEntities rme = new ResourceManageEntities())
            {
                Resource r = rme.Resources.Single<Resource>(x => x.ID == aResource.ID);
                if (r != null)
                {
                    CFileHandler.Instance.DeleteFile(r.FileName);
                    rme.Resources.Remove(r);
                    rme.SaveChanges();
                }
            }
        }

5. Open the file "CFileHandler.cs" in the Library project, and add a function "DeleteFile".

        public void DeleteFile(string aFileName)
        {
            if (!File.Exists(aFileName))
            {
                throw new CException(CException.EXP_WILL_NOT_HAPPEN, "The specified file does not exist!");
            }

            FileHeader header;
            using (FileStream fsInput = new FileStream(aFileName, FileMode.Open))
            {
                BinaryReader br = new BinaryReader(fsInput);
                header = ReadFileHeader(br);
            }

            if (!string.IsNullOrEmpty(header.NextFile))
            {
                string nextFile = Path.Combine(Path.GetDirectoryName(aFileName), header.NextFile);
                DeleteFile(nextFile);
            }

            File.Delete(aFileName);
        }

6. Finished.