The Go Workshop: A New, Interactive Approach to Learning Go

Get started with Go and learn how to leverage its simplicity and flexibility to solve real-world problems and build practical softwareKey FeaturesBuild a comprehensive foundation in Go and focus on developing real-world applicationsExplore the Go Standard Library and learn how to structure your codeLearn how to efficiently interact with files, databases and REST APIsBook DescriptionThe Go Workshop will take the pain out of learning the Go programming language (also known as Golang). It is designed to teach you to be productive in building real-world software. Presented in an engaging, hands-on way, this book focuses on the features of Go that are used by professionals in their everyday work. Each concept is broken down, clearly explained, and followed up with activities to test your knowledge and build your practical skills. Your first steps will involve mastering Go syntax, working with variables and operators, and using core and complex types to hold data. Moving ahead, you will build your understanding of programming logic and implement Go algorithms to construct useful functions. As you progress, you'll discover how to handle errors, debug code to troubleshoot your applications, and implement polymorphism using interfaces. The later chapters will then teach you how to manage files, connect to a database, work with HTTP servers and REST APIs, and make use of concurrent programming. Throughout this Workshop, you'll work on a series of mini projects, including a shopping cart, a loan calculator, a working hours tracker, a web page counter, a code checker, and a user authentication system. By the end of this book, you'll have the knowledge and confidence to tackle your own ambitious projects with Go.What you will learnUnderstand Go syntax and use it to handle data and write functionsDebug your Go code to troubleshoot development problemsSafely handle errors and recover from panicsImplement polymorphism by using interfacesWork with files and connect to external databasesCreate a HTTP client and server and work with a RESTful web APIUse concurrency to design software that can multitaskUse Go Tools to simplify development and improve your codeWho this book is forThe Go Workshop is designed for anyone who is new to Go. Whether you're beginning your journey as an aspiring developer, or are experienced with another programming language and want to branch out to something new, this book will get you on the right track. No prior programming experience is necessary. Cover......Page 1 FM......Page 2 Copyright......Page 3 Table of Contents......Page 4 Preface......Page 22 Chapter 1: Variables and Operators......Page 34 Introduction......Page 35 What Does Go Look Like?......Page 36 Exercise 1.01: Using Variables, Packages, and Functions to Print Stars......Page 42 Activity 1.01 Defining and Printing......Page 43 Exercise 1.02: Declaring a Variable Using var......Page 44 Declaring Multiple Variables at Once with var......Page 45 Exercise 1.03: Declaring Multiple Variables at Once with var......Page 46 Exercise 1.04: Skipping the Type or Value When Declaring Variables......Page 47 Short Variable Declaration......Page 49 Exercise 1.05: Implementing Short Variable Declaration......Page 50 Declaring Multiple Variables with a Short Variable Declaration......Page 51 Exercise 1.06: Declaring Multiple Variables from a Function......Page 52 Using var to Declare Multiple Variables in One Line......Page 53 Non-English Variable Names......Page 54 Exercise 1.07: Changing the Value of a Variable......Page 55 Changing Multiple Values at Once......Page 56 Exercise 1.08: Changing Multiple Values at Once......Page 57 Exercise 1.09 Using Operators with Numbers......Page 58 Shorthand Operator......Page 61 Exercise 1.10: Implementing Shorthand Operators......Page 62 Comparing Values......Page 63 Exercise 1.11: Comparing Values......Page 64 Zero Values......Page 65 Exercise 1.12 Zero Values......Page 66 Value versus Pointer......Page 68 Exercise 1.13: Getting a Pointer......Page 70 Exercise 1.14: Getting a Value from a Pointer......Page 72 Exercise 1.15: Function Design with Pointers......Page 74 Activity 1.02: Pointer Value Swap......Page 76 Constants......Page 77 Exercise 1.16: Constants......Page 78 Enums......Page 80 Scope......Page 82 Activity 1.03: Message Bug......Page 84 Activity 1.04: Bad Count Bug......Page 85 Summary......Page 86 Chapter 2: Logic and Loops......Page 88 if Statements......Page 89 Exercise 2.01: A Simple if Statement......Page 90 if else Statements......Page 91 Exercise 2.02: Using an if else Statement......Page 92 Exercise 2.03: Using an else if Statement......Page 93 The Initial if Statement......Page 94 Exercise 2.04: Implementing the Initial if Statements......Page 95 Activity 2.01: Implementing FizzBuzz......Page 97 Expression switch Statements......Page 99 Exercise 2.05: Using a switch Statement......Page 100 Exercise 2.06: switch Statements and Multiple case Values......Page 101 Exercise 2.07: Expressionless switch Statements......Page 103 Loops......Page 104 Exercise 2.08: Using the for i Loop......Page 105 Exercise 2.09: Looping Over Arrays and Slices......Page 106 The range Loop......Page 107 Exercise 2.10: Looping Over a Map......Page 108 Activity 2.02: Looping Over Map Data Using range......Page 109 break and continue......Page 110 Exercise 2.11: Using break and continue to Control Loops......Page 111 Activity 2.03: Bubble Sort......Page 113 Summary......Page 114 Chapter 3: Core Types......Page 116 Introduction......Page 117 Exercise 3.01: Program to Measure Password Complexity......Page 118 Numbers......Page 121 Integer......Page 122 Exercise 3.02: Floating-Point Number Accuracy......Page 124 Overflow and Wraparound......Page 126 Exercise 3.03: Triggering Number Wraparound......Page 127 Exercise 3.04: Big Numbers......Page 128 Text......Page 130 Rune......Page 132 Exercise 3.05: Safely Looping over a String......Page 134 Activity 3.01: Sales Tax Calculator......Page 137 Activity 3.02: Loan Calculator......Page 138 Summary......Page 140 Chapter 4: Complex Types......Page 142 Collection Types......Page 143 Exercise 4.01: Defining an Array......Page 144 Exercise 4.02: Comparing Arrays......Page 145 Exercise 4.03: Initializing an Array Using Keys......Page 147 Reading from an Array......Page 148 Writing to an Array......Page 149 Exercise 4.05: Writing to an Array......Page 150 Exercise 4.06: Looping Over an Array Using a "for i" Loop......Page 151 Exercise 4.07: Modifying the Contents of an Array in a Loop......Page 153 Activity 4.01: Filling an Array......Page 154 Slice......Page 155 Exercise 4.08: Working with Slices......Page 156 Appending Multiple Items to a Slice......Page 158 Exercise 4.09: Appending Multiple Items to a Slice......Page 159 Activity 4.03: Creating a Locale Checker......Page 160 Creating Slices from Slices and Arrays......Page 161 Exercise 4.10: Creating Slices from a Slice......Page 162 Understanding Slice Internals......Page 163 Exercise 4.11: Using make to Control the Capacity of a Slice......Page 164 Exercise 4.12: Controlling Internal Slice Behavior......Page 166 Map Fundamentals......Page 171 Exercise 4.13: Creating, Reading, and Writing a Map......Page 172 Reading from Maps......Page 173 Exercise 4.14: Reading from a Map......Page 174 Activity 4.04: Slicing the Week......Page 176 Exercise 4.15: Deleting an Element from a Map......Page 177 Simple Custom Types......Page 179 Exercise 4.16: Creating a Simple Custom Type......Page 180 Structs......Page 181 Exercise 4.17: Creating Struct Types and Values......Page 182 Exercise 4.18: Comparing Structs to Each Other......Page 185 Struct Composition Using Embedding......Page 187 Exercise 4.19: Struct Embedding and Initialization......Page 188 Exercise 4.20: Numeric Type Conversion......Page 191 Type Assertions and interface{}......Page 193 Exercise 4.21: Type Assertion......Page 194 Exercise 4.22: Type Switch......Page 196 Activity 4.06: Type Checker......Page 199 Summary......Page 200 Chapter 5: Functions......Page 202 Functions......Page 203 Parts of a function......Page 204 fizzBuzz......Page 207 Exercise 5.01: Creating a Function to Print Salesperson Expectation Ratings from the Number of Items Sold......Page 210 Parameters......Page 212 The Difference between an Argument and a Parameter......Page 214 Exercise 5.02: Mapping Index Values to Column Headers......Page 215 Function Variable Scope......Page 216 Exercise 5.03: Creating a fizzBuzz Function with Return Values......Page 218 Activity 5.01: Calculating the Working Hours of Employees......Page 220 Naked Returns......Page 221 Exercise 5.04: Mapping a CSV Index to a Column Header with Return Values......Page 224 Variadic Function......Page 225 Exercise 5.05: Summing Numbers......Page 229 Anonymous Functions......Page 230 Exercise 5.06: Creating an Anonymous Function to Calculate the Square Root of a Number......Page 232 Closures......Page 233 Exercise 5.07: Creating a Closure Function to Decrement a Counter......Page 235 Function Types......Page 236 Exercise 5.08: Creating Various Functions to Calculate Salary......Page 240 defer......Page 242 Activity 5.02: Calculating Payable Amount for Employees Based on Working Hours......Page 245 Summary......Page 247 Chapter 6: Errors......Page 250 What Are Errors?......Page 251 Syntax Errors......Page 252 Exercise 6.01: Runtime Errors While Adding Numbers......Page 253 Exercise 6.02: Logic Error with Walking Distance......Page 255 Error Handling Using Other Programming Languages......Page 257 Error Interface Type......Page 258 Creating Error Values......Page 261 Exercise 6.03: Creating an Application to Calculate Pay for the Week......Page 262 Panic......Page 265 Exercise 6.04: Crashing the Program on Errors Using panic......Page 270 Recover......Page 273 Exercise 6.05: Recovering from a Panic......Page 275 Activity 6.01: Creating a Custom Error Message for a Banking Application......Page 278 Activity 6.02: Validating a Bank Customer's Direct Deposit Submission......Page 279 Activity 6.03: Panic on Invalid Data Submission......Page 280 Activity 6.04: Preventing a Panic from Crashing the App......Page 281 Summary......Page 282 Chapter 7: Interfaces......Page 284 Introduction......Page 285 Interface......Page 286 Defining an Interface......Page 288 Implementing an Interface......Page 289 Advantages of Implementing Interfaces Implicitly......Page 291 Exercise 7.01: Implementing an Interface......Page 292 Duck Typing......Page 294 Polymorphism......Page 296 Exercise 7.02: Calculating the Area of Different Shapes Using Polymorphism......Page 302 Accepting Interfaces and Returning Structs......Page 305 Empty interface{}......Page 308 Type Assertion and Switches......Page 310 Exercise 7.03: Analyzing Empty interface{} Data......Page 315 Activity 7.01: Calculating Pay and Performance Review......Page 319 Summary......Page 320 Chapter 8: Packages......Page 324 Introduction......Page 325 Reusable......Page 327 Modular......Page 328 What Is a Package?......Page 329 Package Structure......Page 330 Package Naming......Page 331 Package Declarations......Page 333 Exported and Unexported Code......Page 334 GOROOT and GOPATH......Page 336 Package Alias......Page 339 Main Package......Page 340 Exercise 8.01: Creating a Package to Calculate Areas of Various Shapes......Page 341 The init() Function......Page 344 Exercise 8.02: Loading Budget Categories......Page 347 Executing Multiple init() Functions......Page 348 Exercise 8.03: Assigning Payees to Budget Categories......Page 350 Activity 8.01: Creating a Function to Calculate Payroll and Performance Review......Page 351 Summary......Page 352 Chapter 9: Basic Debugging......Page 356 Introduction......Page 357 Methods for Bug-Free Code......Page 358 Performing Logging......Page 359 Exercise 9.01: Working with fmt.Println......Page 360 Formatting Using fmt.Printf()......Page 361 Additional Options for Formatting......Page 365 Exercise 9.02: Printing Decimal, Binary, and Hex Values......Page 368 Basic Debugging......Page 370 Printing Go Variable Types......Page 374 Exercise 9.03 Printing the Go Representation of a Variable......Page 375 Logging......Page 377 Log Fatal Errors......Page 380 Activity 9.01: Building a Program to Validate Social Security Numbers......Page 381 Summary......Page 383 Chapter 10: About Time......Page 386 Making Time......Page 387 Exercise 10.1: Creating a Function to Return a timestamp......Page 390 Comparing Time......Page 391 Duration Calculation......Page 393 Managing Time......Page 396 Exercise 10.2: Duration of Execution......Page 397 Formatting Time......Page 398 Exercise 10.03: What Is the Time in Your Zone?......Page 401 Activity 10.01: Formatting a Date According to User Requirements......Page 402 Activity 10.02: Enforcing a Specific Format of Date and Time......Page 403 Activity 10.03: Measuring Elapsed Time......Page 404 Activity 10.05: Printing the Local Time in Different Time Zones......Page 405 Summary......Page 406 Chapter 11: Encoding and Decoding (JSON)......Page 408 JSON......Page 409 Decoding JSON......Page 413 Struct Tags......Page 415 Exercise 11.01: Unmarshaling Student Courses......Page 421 Encoding JSON......Page 424 Exercise 11.02: Marshaling Student Courses......Page 433 Unknown JSON Structures......Page 437 Exercise 11.03: Analyzing College Class JSON......Page 439 GOB: Go's Own Encoding......Page 442 Exercise 11.04: Using gob to Encode Data......Page 444 Activity 11.01: Mimicking a Customer Order Using JSON......Page 448 Summary......Page 451 Chapter 12: Files and Systems......Page 454 Filesystem......Page 455 File Permissions......Page 456 Flags and Arguments......Page 459 Signals......Page 464 Exercise 12.01: Simulating Cleanup......Page 468 Creating and Writing to Files......Page 471 Reading the Whole File at Once......Page 476 Exercise 12.02: Backing Up Files......Page 483 CSV......Page 488 Activity 12.01: Parsing Bank Transaction Files......Page 492 Summary......Page 495 Chapter 13: SQL and Databases......Page 498 The Database......Page 499 Database API and Drivers......Page 501 Connecting to Databases......Page 502 Creating Tables......Page 505 Inserting Data......Page 508 Exercise 13.01: Creating a Table with Numbers......Page 510 Retrieving Data......Page 512 Updating Existing Data......Page 515 Deleting Data......Page 517 Exercise 13.02: Holding Prime Numbers in a Database......Page 518 Truncating and Deleting Table......Page 521 Activity 13.01: Holding User Data in a Table......Page 522 Activity 13.02: Finding Messages of Specific Users......Page 523 Summary......Page 524 Chapter 14: Using the Go HTTP Client......Page 526 The Go HTTP Client and Its Uses......Page 527 Sending a Request to a Server......Page 528 Exercise 14.01: Sending a Get Request to a Web Server Using the Go HTTP Client......Page 529 Structured Data......Page 531 Exercise 14.02: Using the HTTP Client with Structured Data......Page 532 Activity 14.01: Requesting Data from a Web Server and Processing the Response......Page 534 Sending Data to a Server......Page 535 Exercise 14.03: Sending a Post Request to a Web Server Using the Go HTTP Client......Page 536 Uploading Files in a Post Request......Page 538 Exercise 14.04: Uploading a File to a Web Server via a Post Request......Page 539 Exercise 14.05: Using Custom Headers and Options with the Go HTTP Client......Page 542 Activity 14.02: Sending Data to a Web Server and Checking Whether the Data Was Received Using POST and GET......Page 545 Summary......Page 546 Chapter 15: HTTP Servers......Page 548 How to Build a Basic Server......Page 549 HTTP Handler......Page 550 Exercise 15.01: Creating a Hello World Server......Page 551 Exercise 15.02: Routing Our Server......Page 553 Handler versus Handler Function......Page 556 Activity 15.01: Adding a Page Counter to an HTML Page......Page 557 Activity 15.02: Serving a Request with a JSON Payload......Page 560 Dynamic Content......Page 562 Exercise 15.03: Personalized Welcome......Page 563 Templating......Page 565 Exercise 15.04: Templating Our Pages......Page 567 Static Resources......Page 571 Exercise 15.05: Creating a Hello World Server Using a Static File......Page 572 Getting Some Style......Page 574 Exercise 15.06: A Stylish Welcome......Page 575 Getting Dynamic......Page 579 Activity 15.03: External Template......Page 580 HTTP Methods......Page 582 Exercise 15.07: Completing a Questionnaire......Page 583 JSON loads......Page 587 Exercise 15.08: Building a Server That Accepts JSON Requests......Page 588 Summary......Page 590 Chapter 16: Concurrent Work......Page 592 Goroutines......Page 593 Exercise 16.01: Using Concurrent Routines......Page 594 WaitGroup......Page 597 Exercise 16.02: Experimenting with WaitGroup......Page 598 Race Conditions......Page 600 Atomic Operations......Page 601 Exercise 16.03: An Atomic Change......Page 602 Invisible Concurrency......Page 607 Activity 16.01: Listing Numbers......Page 608 Channels......Page 609 Exercise 16.04: Exchange Greeting Messages via Channels......Page 611 Exercise 16.05: Two-Way Message Exchange with Channels......Page 613 Exercise 16.06: Sum Numbers from Everywhere......Page 614 Exercise 16.07: Request to Goroutines......Page 616 The Importance of Concurrency......Page 618 Exercise 16.08: Equally Splitting the Work between Routines......Page 619 Activity 16.02: Source Files......Page 622 Buffers......Page 623 Exercise 16.09: Notifying When Computation Has Finished......Page 626 HTTP Servers......Page 628 Exercise 16.10: A Structured Work......Page 629 Go Context Package......Page 632 Exercise 16.11: Managing Routines with Context......Page 633 Summary......Page 635 Chapter 17: Using Go Tools......Page 638 Exercise 17.01: Using the go build Tool......Page 639 The go run Tool......Page 640 The gofmt Tool......Page 641 Exercise 17.03: Using the gofmt Tool......Page 642 The goimports Tool......Page 643 Exercise 17.04: Using the goimports Tool......Page 644 The go vet Tool......Page 645 Exercise 17.05: Using the go vet Tool......Page 646 The Go Race Detector......Page 647 Exercise 17.06: Using the Go Race Detector......Page 648 The go doc Tool......Page 650 Exercise 17.07: Implementing the go doc Tool......Page 651 The go get Tool......Page 652 Exercise 17.08: Implementing the go get Tool......Page 653 Activity 17.01: Using gofmt, goimport, go vet, and go get to Correct a File......Page 654 Summary......Page 656 Chapter 18: Security......Page 658 SQL Injection......Page 659 Command Injection......Page 661 Exercise 18.01: Handling SQL Injection......Page 663 Cross-Site Scripting......Page 667 Exercise 18.02: Handling XSS Attacks......Page 668 Hashing Libraries......Page 671 Exercise 18.03: Using Different Hashing Libraries......Page 672 Encryption......Page 674 Exercise 18.04: Symmetric Encryption and Decryption......Page 675 Asymmetric Encryption......Page 677 Exercise 18.05: Asymmetric Encryption and Decryption......Page 678 Random Generators......Page 679 Exercise 18.06: Random Generators......Page 680 Exercise 18.07: Generating a Certificate and Private Key......Page 682 Exercise 18.08: Running an HTTPS Server......Page 686 Password Management......Page 689 Activity 18.01: Authenticating Users on the Application Using Hashed Passwords......Page 690 Activity 18.02: Creating CA Signed Certificates Using Crypto Libraries......Page 691 Summary......Page 692 Chapter 19: Special Features......Page 694 Build Constraints......Page 695 Build Tags......Page 696 Filenames......Page 699 Reflection......Page 700 TypeOf and ValueOf......Page 702 Exercise 19.01: Using Reflection......Page 703 Activity 19.01: Defining Build Constraints Using Filenames......Page 705 DeepEqual......Page 706 Wildcard Pattern......Page 707 The unsafe Package......Page 708 Exercise 19.02: Using cgo with unsafe......Page 710 Activity 19.02: Using Wildcard with Go Test......Page 711 Summary......Page 712 Appendix......Page 716 Index......Page 818 Cut through the noise and get real results with a step-by-step approach to learning Go programming Key Features Ideal for the Go beginner who is getting started for the first time A step-by-step Go tutorial with exercises and activities that help build key skills Structured to let you progress at your own pace, on your own terms Use your physical print copy to redeem free access to the online interactive edition Book Description You already know you want to learn Go, and the smart way to learn anything is to learn by doing. The Go Workshop focuses on building up your practical skills so that you can develop high-performing concurrent applications, or even create Go scripts to automate repetitive daily tasks. You'll learn from real examples that lead to real results. Throughout The Go Workshop, you'll take an engaging step-by-step approach to understanding Go. You won't have to sit through any unnecessary theory. If you're short on time you can jump into a single exercise each day, or you can spend an entire weekend learning how to test and secure your Go applications. It's your choice. Learning on your terms, you'll build up and reinforce key skills in a way that feels rewarding. Every physical print copy of The Go Workshop unlocks access to the interactive edition. With videos detailing all exercises and activities, you'll always have a guided solution. You can also benchmark yourself against assessments, track your progress, and receive content updates. You'll even earn secure credentials that you can share and verify online upon completion. It's a premium learning experience that's included with your printed copy. To redeem it, follow the instructions located at the start of your Go book. Fast-paced and direct, The Go Workshop is the ideal companion for Go beginners. You'll build and iterate on your code like a software developer, learning along the way. This process means that you'll find that your new skills stick, embedded as best practice. A solid foundation for the years ahead. What you will learn Get to grips with Go fundamentals and best practices Learn how to effectively organize your code for production environments Explore how third-party packages can help make you a better engineer Keep your development process bug-free with unit tests and benchmarks Who this book is for Our goal at Packt is to help you be successful, in whatever it is you choose to do. The Go Workshop is an ideal Go tutorial for the Go beginner who is just getti..