Read "Streaming Systems" 1&2, Streaming 101 Read "F1, a distributed SQL database that scales" Read "Zanzibar, Google’s Consistent, Global Authorization System" Read "Spanner, Google's Globally-Distributed Database" Read "Designing Data-intensive applications" 12, The Future of Data Systems IOS development with Swift Read "Designing Data-intensive applications" 10&11, Batch and Stream Processing Read "Designing Data-intensive applications" 9, Consistency and Consensus Read "Designing Data-intensive applications" 8, Distributed System Troubles Read "Designing Data-intensive applications" 7, Transactions Read "Designing Data-intensive applications" 6, Partitioning Read "Designing Data-intensive applications" 5, Replication Read "Designing Data-intensive applications" 3&4, Storage, Retrieval, Encoding Read "Designing Data-intensive applications" 1&2, Foundation of Data Systems Three cases of binary search TAMU Operating System 2 Memory Management TAMU Operating System 1 Introduction Overview in cloud computing 2 TAMU Operating System 7 Virtualization TAMU Operating System 6 File System TAMU Operating System 5 I/O and Disk Management TAMU Operating System 4 Synchronization TAMU Operating System 3 Concurrency and Threading TAMU Computer Networks 5 Data Link Layer TAMU Computer Networks 4 Network Layer TAMU Computer Networks 3 Transport Layer TAMU Computer Networks 2 Application Layer TAMU Computer Networks 1 Introduction Overview in distributed systems and cloud computing 1 A well-optimized Union-Find implementation, in Java A heap implementation supporting deletion TAMU Advanced Algorithms 3, Maximum Bandwidth Path (Dijkstra, MST, Linear) TAMU Advanced Algorithms 2, B+ tree and Segment Intersection TAMU Advanced Algorithms 1, BST, 2-3 Tree and Heap TAMU AI, Searching problems Factorization Machine and Field-aware Factorization Machine for CTR prediction TAMU Neural Network 10 Information-Theoretic Models TAMU Neural Network 9 Principal Component Analysis TAMU Neural Network 8 Neurodynamics TAMU Neural Network 7 Self-Organizing Maps TAMU Neural Network 6 Deep Learning Overview TAMU Neural Network 5 Radial-Basis Function Networks TAMU Neural Network 4 Multi-Layer Perceptrons TAMU Neural Network 3 Single-Layer Perceptrons Princeton Algorithms P1W6 Hash Tables & Symbol Table Applications Stanford ML 11 Application Example Photo OCR Stanford ML 10 Large Scale Machine Learning Stanford ML 9 Anomaly Detection and Recommender Systems Stanford ML 8 Clustering & Principal Component Analysis Princeton Algorithms P1W5 Balanced Search Trees TAMU Neural Network 2 Learning Processes TAMU Neural Network 1 Introduction Stanford ML 7 Support Vector Machine Stanford ML 6 Evaluate Algorithms Princeton Algorithms P1W4 Priority Queues and Symbol Tables Stanford ML 5 Neural Networks Learning Princeton Algorithms P1W3 Mergesort and Quicksort Stanford ML 4 Neural Networks Basics Princeton Algorithms P1W2 Stack and Queue, Basic Sorts Stanford ML 3 Classification Problems Stanford ML 2 Multivariate Regression and Normal Equation Princeton Algorithms P1W1 Union and Find Stanford ML 1 Introduction and Parameter Learning

A little filter in your rails app

2016-05-20

Scenario

As a reader
When I click on category 'rails'
Then I should see articles of that category

If you want some practice, go for saas book’s RottenPotatoes demo. You will get a better understanding of filter and session stuff in rails! If you get stuck, you can have a look at my code as a poor reference, Lol, come here.

Getting things done in rails

Three points need to be considered. Routing, Controller and View(Since it’s very simple, we don’t need to resort to Model).

Routing

Make sure there is url mapped to desired controller#action(here we use index action), say there is a rails button to trigger this action. Code should look kind of like this:

<%= link_to "rails", posts_path(:category => 'rails') %>

As shown in the code, :category => 'rails' will be passed to params, which is handy.

Controller

In you post controller, change index action:

#before
def index
	@posts = Post.all.order('created_at desc')
end
#after
def index
	category = params[:category]
	if category
		@posts = Post.where("category = ?", category).order('created_at desc')
	else
		@posts = Post.all.order('created_at desc')
	end
end

View

Since we use index action, there should be index.html.erb or index.html.haml. So we do not need to handle that. But it should looks somewhat like this:

<div id="posts_wrapper" class="skinny_wrapper">
	<% @posts.each do |post| %>
		<div class="post">
			<p class="date"><%= post.created_at.strftime("%A, %B, %d") %></p>
			<h2><a href="#"><%= link_to post.title, post %></a></h2>
			<hr>
		</div>
	<% end %>
</div>

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