Random training material

Random training material

• Random training material
  • I know how to do this with Node.js
  • Learning resources
  • stdlib
  • Installing global tools
  • Uppercase enforced acronyms
  • init functions
  • Go modules
  • pgFormatter
  • SQLBoiler
  • Testing
  • When to use context to store things?
  • Slices
  • CLI
  • gogenerate
  • goswagger
  • Error handling in go

I know how to do this with Node.js

https://github.com/miguelmota/golang-for-nodejs-developers

Learning resources

• https://github.com/inancgumus/learngo
• https://quii.gitbook.io/learn-go-with-tests/
• https://www.manning.com/books/go-in-practice

stdlib

Get an overview of the stdlib of go itself first! https://golang.org/pkg/#stdlib

Go formatting directives https://golang.org/pkg/fmt/

panic means an unexpected condition arises in your Go program due to which the execution of your program is terminated Mostly we use it to fail fast on errors that shouldn’t occur during normal operation, or that we aren’t prepared to handle gracefully. https://gobyexample.com/panic Do not use panic in normal scenarios, eventually only for on-off cli utils

Installing global tools

We might want to install some go-based tools that are not being imported, but are used as part of project’s development environment. The officially recommended approach is to add a tools.go file (the name doesn’t matter).

See How can I track tool dependencies for a module? See Tools as dependencies

For automated install for go tools refer to Manage Go Tools via Go Modules

Uppercase enforced acronyms

Words in names that are initialisms or acronyms (e.g. "URL" or "NATO") have a consistent case. For example, "URL" should appear as "URL" or "url" (as in "urlPony", or "URLPony"), never as "Url". As an example: ServeHTTP not ServeHttp. For identifiers with multiple initialized "words", use for example "xmlHTTPRequest" or "XMLHTTPRequest". https://github.com/golang/go/wiki/CodeReviewComments#initialisms https://stackoverflow.com/questions/52358247/what-are-golang-struct-field-naming-conventions https://github.com/golang/lint/blob/master/lint.go#L770

init functions

init is [automatically] called after all the variable declarations in the package have evaluated their initializers, and those are evaluated only after all the imported packages have been initialized.

https://golang.org/doc/effective_go.html#init https://medium.com/golangspec/init-functions-in-go-eac191b3860a

Go modules

Go modules

On a more general note, the purpose of go mod tidy is to also add any dependencies needed for other combinations of OS, architecture, and build tags. Make sure to run this before every release.

Go modules by example

pgFormatter

We use pgFormatter both in VSCode and in our Makefile to enforce a proper formatting to all *.sql files https://marketplace.visualstudio.com/items?itemName=bradymholt.pgformatter https://github.com/darold/pgFormatter

SQLBoiler

About UUID support: https://github.com/volatiletech/sqlboiler/issues/58

No global function variants We can't use the global db variant, as we don't want to lose the ability to do parallel testing, see function variations The idea is to use the db that's available on the server struct, which means you always need to pass the server or db to your functions (same as it should happen with context anyways)

panic variants might be handy for one-off tasks but in general are dangerours. Do not use them in a regular service.

hooks Won't hopefully be required, refrain from using them unless you have a very very good reason.

Testing

Black-Box Testing (packages with _test suffix) is also required to deal with cyclic dependency imports.

• https://stackoverflow.com/questions/19998250/proper-package-naming-for-testing-with-the-go-language/31443271#31443271
• https://github.com/golang/go/issues/25223

TestMain would be executed once per package (and is not required any more by us)

• https://www.reddit.com/r/golang/comments/7x4czh/namespacing_integration_tests_with_testmain/
• https://stackoverflow.com/questions/51026376/golang-global-setup-for-all-tests-within-same-and-other-sub-modules
• https://groups.google.com/forum/#!topic/golang-nuts/SxEkZhWl3QA

Regarding t.* log methods https://golang.org/pkg/testing/#B.Error

• Fail marks the function as having failed but continues execution.
• FailNow marks the function as having failed and stops its execution by calling runtime.Goexit (which then runs all deferred calls in the current goroutine).
• Error is equivalent to Log followed by Fail.
• Fatal is equivalent to Log followed by FailNow.

Regarding testdata directory https://medium.com/@povilasve/go-advanced-tips-tricks-a872503ac859 Firstly, go build ignores directory named testdata. Secondly, when go test runs, it sets current directory as package directory.

• https://dave.cheney.net/2016/05/10/test-fixtures-in-go Second, the Go tool will ignore any directory in your $GOPATH that starts with a period, an underscore, or matches the word testdata

stdout and stderr are hijacked while testing, you will only receive output on test failure or when running with the -v flag (enabled in VSCode when running tests from there)

• https://blog.blueberry.io/end-to-end-tests-in-go-and-postgresql-40bc4884ac42
• https://medium.com/rungo/unit-testing-made-easy-in-go-25077669318

Random test related resources

• https://ieftimov.com/post/testing-in-go-fixtures/

Create a server instance inside each test — if expensive things lazy load, this won’t take much time at all, even for big components https://pace.dev/blog/2018/05/09/how-I-write-http-services-after-eight-years.html

When to use context to store things?

Context.Value should inform, not control https://medium.com/@cep21/how-to-correctly-use-context-context-in-go-1-7-8f2c0fafdf39

Use context Values only for request-scoped data that transits processes and APIs, not for passing optional parameters to functions. That said, people do use this approach. And if your project consists of a sprawling set of packages – and using a global config is out of the question – it's quite an attractive proposition.

• https://www.alexedwards.net/blog/organising-database-access -- Dependency injection approch currently used, we do not want to use the Request-scoped context for this!

The go vet tool checks that CancelFuncs are used on all control-flow paths. Programs that use Contexts should follow these rules to keep interfaces consistent across packages and enable static analysis tools to check context propagation The same Context may be passed to functions running in different goroutines; Contexts are safe for simultaneous use by multiple goroutines. https://golang.org/pkg/context/

Slices

https://github.com/golang/go/wiki/SliceTricks FIFO / Queues -- https://stackoverflow.com/questions/23531891/how-do-i-succinctly-remove-the-first-element-from-a-slice-in-go/23532104

CLI

https://golang.org/pkg/flag/ scripts, parsing CLI flags

gogenerate

Sample stringer -- https://medium.com/@arjun.mahishi/golang-stringer-ad01db65e306

goswagger

why are required string pointer types? https://github.com/go-swagger/go-swagger/issues/1188

Add it to the required array
Set MinLength: 1
Set x-nullable: false

https://medium.com/@pedram.esmaeeli/generate-swagger-specification-from-go-source-code-648615f7b9d9

How to add response descriptions: https://github.com/go-swagger/go-swagger/issues/738#issuecomment-273014052

Error handling in go

In Go, error handling is important. The language's design and conventions encourage you to explicitly check for errors where they occur (as distinct from the convention in other languages of throwing exceptions and sometimes catching them). https://blog.golang.org/error-handling-and-go

Go’s approach makes it easy to see which functions return errors and to handle them using the same language constructs employed for any other, non-error tasks. https://gobyexample.com/errors