Rapid UI Development with Blazor (and Tailwind CSS)

Many code problems are caused by premature abstraction

Naming a CSS class is defining an abstraction

Tailwind offers a fast way to iterate your design using utility classes

Make the button more 'button like'

bg-blue-300

text-white

p-4

m-8

rounded-md

shadow-lg

https://tailwindcss.com/docs

text-xl

text-2xl

my-8

px-4

Add 'interactivity' with pseudo-class variants

Give your button a different look on hover

hover:

Hover Variant

Handle different screen sizes with breakpoints

sm:

Breakpoints

md:

lg: 

xl:

640px

768px

1024px

1280px

Lean on .NET 6 Hot Reload to quickly iterate your design

Refactor markup into separate components to simplify your UI code

Refactor the button markup into a separate component

Render multiple instances of the button on the original page

Make each button have different text

Code that's easy to move is easy to refactor

Use parameters to pass values to your component

<FancyButton text="Click me"></FancyButton>
<button>@Text</button>

[Parameter]
public string Text { get;set; }

FancyButton.razor

Use ChildContent RenderFragments to 'inject markup' into your components

<FancyButton>Click me</FancyButton>
<button>@ChildContent</button>

[Parameter]
public RenderFragment ChildContent { get;set; }

FancyButton.razor

Design (and render) a 'Panel' component for a dashboard

A Panel

Some interesting panel content (could be anything really)

Weather

Forecast

Active Users

Weekly Sales

A Panel

Some interesting panel content (could be anything really)

<button>@ChildContent</button>

[Parameter]
public RenderFragment ChildContent { get;set; }

Design (and render) a 'Panel' component for a dashboard

Flex is really useful for controlling layout

 (once you grasp the basics)

<div class="flex …">
    <div>A Panel</div>
    <div>
        Some interesting content
    </div>
</div>
<div class="flex …">
    <div>A Panel</div>
    <div>
        Some interesting content
    </div>
</div>
<div class="flex flex-col …">
    <div>A Panel</div>
    <div>
        Some interesting content
    </div>
</div>
<div class="flex …">
    <div>A Panel</div>
    <div>
        Some interesting content
    </div>
</div>
<div class="flex flex-col …">
    <div>A Panel</div>
    <div class="border">
        Some interesting content
    </div>
</div>
<div class="flex …">
    <div>A Panel</div>
    <div>
        Some interesting content
    </div>
</div>
<div class="flex flex-col …">
    <div>A Panel</div>
    <div class="flex-1">
        Some interesting content
    </div>
</div>

Make the panels flow across the page

Weather

Forecast

Active Users

Weekly Sales

flex

flex-row

flex-col

Container

Bonus options

flex-wrap

gap-x

For some cases, CSS Grid is a better option (and easier to understand)

Weather

Forecast

Active Users

Weekly Sales

grid

grid-cols-2

grid-rows-2

New requirement: We need 'important' panels

Modify the existing Panel component so it can be 'normal' or 'important'

Important panels should look 'different' to 'normal' panels.

Make at least one of your panels important

Important panels revisited

Start over :)

Make it possible to have an important panel.

 

This time you cannot make any changes to the existing Panel component

Break Time!

Different ways to manage 'variation' in components

  • Conditional logic
  • Completely separate components
  • Specialised overrides/variations

Add an 'inactive' panel to the dashboard

Create a new 'specialised' component which renders the panel with different styles (to visually show it is 'inactive')

Feel free to use Important Panel for inspiration

A Panel

Some interesting panel content (could be anything really)

Links, buttons here

Action bar

Implement an Action Bar (in the primary Panel component)

Implement an Action Bar (in the primary Panel component)

A component can have multiple Parameters of type RenderFragment

An alternative way to declare content for render fragments…

Tips

<YourComponent>
    <ChildContent>
        <h3>Hello World</h3>
    </ChildContent>
</YourComponent>

A Panel

Some interesting panel content (could be anything really)

Links, buttons here

<div class="flex flex-col">
    <div>@Title</div>
    <div class="flex-1">
        @ChildContent
    </div>
    @if (Actions != null)
    {
        <div>
            @Actions
        </div>       
    }
</div>
@code {
    [Parameter]
    public string Title { get; set; }

    [Parameter]
    public RenderFragment ChildContent { get; set; }
    
    [Parameter]
    public RenderFragment Actions { get; set; }
}

Panel.razor

<div class="flex gap-4">
    <Panel Title="Panel A">
        <ChildContent>
            A Panel
        </ChildContent>
        <Actions>
            <a href="/">View</a>
        </Actions>
    </Panel>
    <ImportantPanel Title="Panel B">
        Panel
    </ImportantPanel>
</div>

Index.razor

<Panel Title="@Title" PrimaryBackgroundColor="bg-red-400">
    @ChildContent
</Panel>

ImportantPanel.razor

@code {

    [Parameter]
    public string Title { get; set; }

    [Parameter]
    public RenderFragment ChildContent { get; set; }

}
<Panel Title="@Title" PrimaryBackgroundColor="bg-red-400" 
       Actions="@Actions">
    @ChildContent
</Panel>

ImportantPanel.razor

@code {

    [Parameter]
    public string Title { get; set; }

    [Parameter]
    public RenderFragment ChildContent { get; set; }
    
    [Parameter]
    public RenderFragment Actions { get; set; }

}
<Panel Title="@Title" PrimaryBackgroundColor="bg-red-400" 
       Actions="@Actions" ChildContent="@ChildContent">    
</Panel>

ImportantPanel.razor

@code {

    [Parameter]
    public string Title { get; set; }

    [Parameter]
    public RenderFragment ChildContent { get; set; }
    
    [Parameter]
    public RenderFragment Actions { get; set; }

}
<Panel Title="@Title" PrimaryBackgroundColor="bg-red-400">
    <ChildContent>
        @ChildContent
    </ChildContent>
    <Actions>
        @Actions
    </Actions>
</Panel>

ImportantPanel.razor

@code {

    [Parameter]
    public string Title { get; set; }

    [Parameter]
    public RenderFragment ChildContent { get; set; }
    
    [Parameter]
    public RenderFragment Actions { get; set; }

}

Use attribute splatting to let your component handle any parameter

Attribute Splatting for Render Fragments?

Component re-use can lead to 'God components'

Smaller, simpler components 

  • Are easier to reason about
  • Have fewer reasons to change
  • Are easier to compose together

Take a look at this Kanban board

How might you refactor this into smaller components?

  • Spend a few moments exploring the code
  • Look for 'seams'

Extract the card into its own component

Refactor the card into its own component

 

Use the new component in place of the original markup (in the Kanban board)

Structure is hard to see when it's spread between multiple components

Push layout classes 'up' where possible

Classes like gap-x and flex in containing elements enable children to remain layout agnostic

  1. Look for seams (markup you can extract)
     
  2. Try moving the markup into a separate component
     
  3. Use Parameters to bring in any data that's needed
     
  4. Implement callback(s) to signal 'events' back to up to the parent component

A repeatable process for refactoring your components

Build a products page

Keep all the markup in the main page (for now)

Build the UI "in situ" to avoid premature abstractions

Then refactor (to simplify the UI)

Refactor the product "card" into its own component

Resist the temptation to re-use "similar" components

Make a component work hard to prove it really is the same thing

Kanban 'card' != Product 'card'

https://github.com/Practical-ASP-NET/BlazorTailwindTemplate

Useful Links

Tailwind dotnet new project template

Break Time!

Keep related code and UI as close as possible

A

B

Connascense

"Born Together"

A

B

Locality Matters

A

B

public class WorkItem
{
    public void AssignToUser(User assignedBy, User assignedTo)
    {
        // assign task to user
        
        if (assignedTo.Role == "manager")
        {
            // send manager email
            // to let them know they've been asked to look at something
        }
    }
}

Connaescense of Value

A

B

public class User
{
    public string Role { get; set; }
    public bool IsManager => Role == "Manager";
    
    public void AssignManagementRole()
    {
        Role = "Manager";
    }
}

A

B

public class WorkItem
{
    public void AssignToUser(User assignedBy, User assignedTo)
    {
        // assign task to user
        
        if (assignedTo.IsManager)
        {
            // send manager email
            // to let them know they've been asked to look at something
        }
    }
}

Software Engineering Topic of the Day #26

https://cloudnative.ly/connascense-9b3972c57415
 

https://connascence.io/

Useful Links

Watch out for

side effects

in components making it harder to refactor

ProductList

Fetch list from API

Fetch list from API

ProductList

Product Id

ProductCard

Fetch specific details from API

Fetch list from API

ProductList

Product Id

ProductCard

Fetch specific details from API

Price

Delivery

Fetch price from API

Product Id

Product Id

Fetch Delivery Cost from API

Fetch list from API

Fetch specific details from API

Fetch price from API

Fetch Delivery Cost from API

Fetch list from API

Fetch list from API

ProductDetails { id, imageUrl, description, price }

ProductDetails { id, imageUrl, description, price }

ProductDetails { id, imageUrl, description, price }

Fetch list from API

ProductDetails { id, imageUrl, description, price }

DeliveryCost { price }

PriceDetails { price }

Fetch list from API

ProductDetails { id, imageUrl, description, price }

Price

Price

Organise components by feature for easier ongoing development

Features
  - Components
  - Feature A
    - Components
    - Index.razor
  - Feature B
    - Components
    - Index.razor
  Index.razor
Features
  - Components
  - Profile
    - Components
    - Index.razor
  - Dashboard
    - Components
    - Index.razor
  Index.razor
Features
  - Components
  - Profile
    - Components
      - Achievements.razor
      - Avatar.razor
    - Index.razor
  - Dashboard
    - Components
      - Panel.razor
      - ImportantPanel.razor
    - Index.razor
  Index.razor

Profile

Dashboard

Components

Panel.razor

Index.razor

Index.razor

Courses

Features

Components

Panel.razor

Profile

Index.razor

Index.razor

Features
  - Components
  - Profile
    - Components
      - Achievements.razor
      - Avatar.razor
    - Index.razor
  - Dashboard
    - Components
      - Panel.razor
      - ImportantPanel.razor
    - Index.razor
  Index.razor
Features
  - Components
    - Panel.razor
    - ImportantPanel.razor
  - Profile
    - Components
      - Achievements.razor
      - Avatar.razor
    - Index.razor
  - Dashboard
    - Components
    - Index.razor
  Index.razor

https://jonhilton.net/blazor-component-folder-structure/

Atomic Design is a useful way to think about the hierarchy of your UI

Open API makes it much easier to consume an API

You can use Refit to connect to your API with less boilerplate code

Wire up the boards list component to the API

Make a call to Api.GetBoards()
(note, the method is async)

Render the list of boards in the UI (using the data returned from the Api call)

Watch out for nullable reference types

https://devblogs.microsoft.com/dotnet/

embracing-nullable-reference-types/

Automatically generate your client to save even more code (and time)

Auto-generate a Refit client from the Donatello API

From the command line/terminal

dotnet tool install -g refitgenerator
cd ExampleClient
regen -u https://donatello-9hwr4.ondigitalocean.app/swagger/v1/swagger.json

Where 'ExampleClient' is a folder in which you're happy to create the client!

https://github.com/velorien/refitgenerator

Useful Links (Refit)

https://github.com/reactiveui/refit

Refit

Refit generator (from OpenApi Schemas)

NSwag is another option for generating clients

Q and A

(AKA phew, we made it!)

Rapid UI development with Blazor workshop

By jonhilt

Rapid UI development with Blazor workshop

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