StarBlog Development Notes (13): Adding the Friend Links Feature

Series Articles

• Developing a Blog Project with .NetCore: StarBlog - (1) Why Write Your Own Blog?
• Developing a Blog Project with .NetCore: StarBlog - (2) Environment Setup and Creating the Project
• Developing a Blog Project with .NetCore: StarBlog - (3) Model Design
• Developing a Blog Project with .NetCore: StarBlog - (4) Batch Import of Markdown Blog Posts
• Developing a Blog Project with .NetCore: StarBlog - (5) Starting to Build the Web Project
• Developing a Blog Project with .NetCore: StarBlog - (6) Page Development: Blog Post List
• Developing a Blog Project with .NetCore: StarBlog - (7) Page Development: Post Detail Page
• Developing a Blog Project with .NetCore: StarBlog - (8) Displaying the Category Hierarchy
• Developing a Blog Project with .NetCore: StarBlog - (9) Batch Image Import
• Developing a Blog Project with .NetCore: StarBlog - (10) Image Waterfall Layout
• Developing a Blog Project with .NetCore: StarBlog - (11) Implementing Visit Statistics
• Developing a Blog Project with .NetCore: StarBlog - (12) Dynamic Compilation of Razor Pages
• Developing a Blog Project with .NetCore: StarBlog - (13) Adding the Friend Links Feature
• ...

Preface

Time flies—just like that, the blog has already been live for a week (URL: http://blog.deali.cn)

The page views aren't high, but for a site that hasn't done any SEO, it's already pretty good~

I've been busy during this time, but I've still been writing code to keep improving the blog (Commits on Github every single day)

And here it is, the friend links feature is here~

This article will walk through the implementation of this feature step by step.

All project code has also been uploaded to GitHub. Stars/Forks from you experts are welcome!

• Blog backend + frontend project: https://github.com/Deali-Axy/StarBlog
• Admin dashboard frontend project: https://github.com/Deali-Axy/StarBlog-Admin

See the Result First

Analysis

Let's analyze the feature first

Friend links can be added manually, or applied for by people visiting the site

Other site owners can apply to exchange friend links. After submitting an application, it can be seen in the blog admin backend, and once confirmed it will show up on the site~

That's the initial feature design

Of course I also thought of some extended features, such as adjusting the display order of links based on click counts (Baidu: why does that sound so familiar)

Modeling

Based on the requirements, we need two models

One is the friend links to display, and the other is friend link application records

Let's get started

Create the data models in StarBlog.Data/Models

/// <summary>
/// 友情链接
/// </summary>
public class Link {
    [Column(IsIdentity = true, IsPrimary = true)]
    public int Id { get; set; }

    /// <summary>
    /// 网站名称
    /// </summary>
    public string Name { get; set; }

    /// <summary>
    /// 介绍
    /// </summary>
    public string? Description { get; set; }

    /// <summary>
    /// 网址
    /// </summary>
    public string Url { get; set; }

    /// <summary>
    /// 是否显示
    /// </summary>
    public bool Visible { get; set; }
}

And this one as well

/// <summary>
/// 友情链接申请记录
/// </summary>
public class LinkExchange {
    [Column(IsIdentity = true, IsPrimary = true)]
    public int Id { get; set; }

    /// <summary>
    /// 网站名称
    /// </summary>
    public string Name { get; set; }

    /// <summary>
    /// 介绍
    /// </summary>
    public string? Description { get; set; }

    /// <summary>
    /// 网址
    /// </summary>
    public string Url { get; set; }

    /// <summary>
    /// 站长
    /// </summary>
    public string WebMaster { get; set; }

    /// <summary>
    /// 联系邮箱
    /// </summary>
    public string Email { get; set; }

    /// <summary>
    /// 是否已验证
    /// <para>友情链接需要验证后才显示在网站上</para>
    /// </summary>
    public bool Verified { get; set; } = false;

    /// <summary>
    /// 申请时间
    /// </summary>
    public DateTime ApplyTime { get; set; } = DateTime.Now;
}

Service

With the models ready, next let's flesh out the logic

Write the logic in StarBlog.Web/Services

First, for friend links, besides CRUD, also add a shortcut for setting visibility

public class LinkService {
    private IBaseRepository<Link> _repo;

    public LinkService(IBaseRepository<Link> repo) {
        _repo = repo;
    }

    /// <summary>
    /// 获取全部友情链接
    /// </summary>
    /// <param name="onlyVisible">只获取显示的链接</param>
    /// <returns></returns>
    public List<Link> GetAll(bool onlyVisible = true) {
        return onlyVisible
            ? _repo.Where(a => a.Visible).ToList()
            : _repo.Select.ToList();
    }

    public Link? GetById(int id) {
        return _repo.Where(a => a.Id == id).First();
    }

    public Link? GetByName(string name) {
        return _repo.Where(a => a.Name == name).First();
    }

    public Link AddOrUpdate(Link item) {
        return _repo.InsertOrUpdate(item);
    }

    public Link? SetVisibility(int id, bool visible) {
        var item = GetById(id);
        if (item == null) return null;
        item.Visible = visible;
        _repo.Update(item);
        return GetById(id);
    }

    public int DeleteById(int id) {
        return _repo.Delete(a => a.Id == id);
    }
}

Nothing special here

Continuing

Logic for managing friend link application records, which also has CRUD. This part of the code is the same as above, so it's omitted

Here I'll only paste the code for setting verification status

public class LinkExchangeService {
    private readonly IBaseRepository<LinkExchange> _repo;
    private readonly LinkService _linkService;

    public LinkExchangeService(IBaseRepository<LinkExchange> repo, LinkService linkService) {
        _repo = repo;
        _linkService = linkService;
    }
    
	// 设置是否验证
    public LinkExchange? SetVerifyStatus(int id, bool status) {
        var item = GetById(id);
        if (item == null) return null;

        item.Verified = status;
        _repo.Update(item);


        var link = _linkService.GetByName(item.Name);
        if (status) {
            if (link == null) {
                _linkService.AddOrUpdate(new Link {
                    Name = item.Name,
                    Description = item.Description,
                    Url = item.Url,
                    Visible = true
                });
            }
            else {
                _linkService.SetVisibility(link.Id, true);
            }
        }
        else {
            if (link != null) _linkService.DeleteById(link.Id);
        }

        return GetById(id);
    }
}

In the method for setting verification status, it implements:

• Setting an application as verified automatically adds that application's link to the friend links
• Setting an application as unverified automatically deletes the corresponding friend link (if it exists)

The rest is the same as the friend links above.

Don't forget to register the services after writing them

builder.Services.AddScoped<LinkExchangeService>();
builder.Services.AddScoped<LinkService>();

Adding Data

Although I also wrote APIs for managing these links, this series of articles is still covering the frontend part, so I plan to save the API implementation for the later RESTFul API development section~

So for now, let's just add them directly in the database~

Page Display

The data models and logic are all implemented. Next is finding a suitable place to display them

After looking at a few similar blogs, I decided to put the friend links at the bottom of the homepage

Edit StarBlog.Web/ViewModels/HomeViewModel.cs and add a new property

public class HomeViewModel {
    /// <summary>
    /// 友情链接
    /// </summary>
    public List<Link> Links { get; set; } = new();
}

Use Bootstrap5's responsive variation to make a responsive friend links display

<div class="d-grid gap-2 d-md-block">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

The example on the official site looks like this

It's okay-ish, but they're all the same color, too monotonous. I want them colorful!

Encapsulating a Razor Component

So I encapsulated a Razor component named ColorfulButton

First define the ViewModel, used to configure this component

Add a ColorfulButtonViewModel.cs file in StarBlog.Web/ViewModels. The code is as follows

public static class LinkTarget {
    public const string Blank = "_blank";
    public const string Parent = "_parent";
    public const string Self = "_self";
    public const string Top = "_top";
}

public class ColorfulButtonViewModel {
    public string Name { get; set; }
    public string Url { get; set; } = "#";
    public string Target { get; set; } = "_self";
}

Then add ColorfulButton.cshtml under StarBlog.Web/Views/Shared/Widgets

Put in the button colors Bootstrap supports, then randomly show one each time~

@model ColorfulButtonViewModel

@{
    var rnd = Random.Shared;
    var colorList = new[] {
        "btn-outline-primary",
        "btn-outline-secondary",
        "btn-outline-success",
        "btn-outline-danger",
        "btn-outline-warning",
        "btn-outline-info",
        "btn-outline-dark",
    };
    var btnColor = colorList[rnd.Next(0, colorList.Length)];
}

<a href="@Model.Url" role="button" class="btn btn-sm @btnColor mb-1" target="@Model.Target">
    @Model.Name
</a>

Add to the Page

The component is done. Finally, implement the friend-link display on the homepage.

Edit the StarBlog.Web/Views/Home/Index.cshtml file

Add the following code at the bottom (below the recommended blogs section)

<div class="container px-4 py-3">
    <h2 class="pb-2 border-bottom">Link Exchange</h2>
    @if (Model.Links.Count > 0) {
        <div class="d-grid gap-2 d-md-block">
            @foreach (var link in Model.Links) {
                @await Html.PartialAsync("Widgets/ColorfulButton",
                    new ColorfulButtonViewModel { Name = link.Name, Url = link.Url })
            }
        </div>
    }
    else {
        @await Html.PartialAsync("Widgets/PlaceholderCard", "友情链接")
    }
</div>

The final result is as shown at the beginning: every visit gets a different color. Super cool~

Done

That's it. A simple feature that can add a little color to an otherwise plain blog~

Fellow site owners are also welcome to exchange friend links~!