Exploring Golang features

You can incorporate these code snippets into your larger programming modules. This repository is viewable on sourcegraph.com.

Contents

Name	Description
00_persisting_go	Installing Go, persisting on systemd, Upstart
01_data_type	type, error, recursion, reference, sort, switch, type assertion
02_mongodb_aggregate_cli	aggregate data from mongodb displayed in CLI
03_mongodb_find_sort_cli	MongoDB Find All, Sort commands, results in CLI
04_get_url_variable	Get "FormValue" variable from URL
05_mongodb_crud_cli	Insert, Update, Drop, Find, Index commands, results in CLI
06_ajax_send_receive	Two Ajax examples: read and write
07_one_page_template	GO code and HTML template in one file
08_gowiki	Simple wiki example
09_todo_list_html	Todo list with struct and HTML template.
10_mongodb	Mongodb query results on HTML page in one go file.
11_socket_send_receive	Send/receive text between client/server via socket.
12_mgo_pipeline	Mongodb pipeline query saved in one go file
13_qr_barcode	QR code generator displays PNG image in browser.
14_read_txt_file	Compare ways to process TXT file
15_png_or_svg_barchart	generate bar chart, PNG or SVG
16_drop_down_menu_form	Form /w drop down menu, template with sub-templates
17_mysql_user_login	MySQL for user registration, login, and user list.
18_cookie_authentication	Authentication with cookies.
19_os_global_variables	Displaying all global system variables.
20_mongodb_crud	Mongodb CRUD with REST using httprouter & HTML templates
21_httprouter_template	html template with httprouter and ServeFiles
22_mongodb_crud_rest_html	Mongodb CRUD with REST using httprouter & HTML templates
23_file_uploader	Upload file and save on server
24_calculate_time	Time related features
25_https_static_files	Serve HTTP and HTTPS w/ NotFound for static files
26_url_not_found_handler	Custom Not Found handler.
27_mongodb_bulk_upsert	Mongodb bulk insert from TXT file
28_markdown	Generate Markdown using blackfriday
29_go_crud_json_api	REST API using JSON with httprouter. JavaScript is used to view, create, edit, and delete records.
30_mongodb_crud_json_api	REST API using JSON, httprouter, and toml, i/o to MongoDB
31_send_email	Send email with attachment
32_colorful_cli	Create colorful CLI
33_testing	Testing package example
34_channels	Buffered/unbuffered channels, forking channel, ranging over closed channel.
35_mongodb_pipeline_page	One page MGO aggregation with pipeline
36_concurrency_channel	Channel, waiting, concurrency, sleep, close, count, queue
37_html_template	Simple html template with Go
38_url_request_JSON	Convert data to/from JSON, get and parse file from URL
39_read_directory_content	List files adn sub folders in a given folder
40_cron_scheduler	Schedule processes
41_cli_arguments	Run cli utility with options using os.Args
42_upload_many_files	Upload multiple files from browser form to folder on a server.
43_resize_jpg_png_image	Resize images
44_csv_file	Read and write to CSV file. Parse CSV file to slice of objects.
45_image_exif_data	Get image attributes for each image in a folder.
46_video_capture	Capture video from web camera and display live.
47_download_slice_as_csv	Download link generates CSV or Tab Delimited file that can be saved localy on your computer.
48_keyboard_driver	Testing IOT devices
49_constructor	Example creating new package with allocation/constructor that accepts multiple types using interface. Experimenting with Readers and Writers.
50_golf_framework	A fast, simple and lightweight micro-web framework for Go
51_blur_image	Blur, Rotate, and Generate Thumbnails.
52_jpg_image_watermark	Add watermark to image
53_regular_expression	Validation, Find and replace, security
54_rotate_image	Image rotation in degrees from 1 to 360.
55_html_template_std_lib	HTML template using standard library packages
56_html_formatter	Work in similar fashion as go fmt, but on HTML files.
57_valid_interface	Interface as parameter.
58_GO_HTML_template	Go HTML template examples.
59_zip_and_unzip	Example for archive/zip package.
60_http_response_as_file	HTTP handler responds with a copied file.
61_logging_middleware	Save logs and error logs to file or database.
62_download_progress	Progress shown on CLI.
63_graphql_todo_example	One file GraphQL example.
64_
65_books_example	MongoDB CRUD example.
66_server_sent_events	Live logs (events) from server to browser using the EventSource HTML interface.
67_stringutil	Reverse a string, test included
68_iota	Iota identifier is used in const declarations to simplify definitions of incrementing numbers.
69_JSON	JSON input/output examples

The proper way to copy a slice

package main

import "fmt"

func main() {
	a := []string{"a", "b", "c", "d"}
	e := make([]string, len(a))
	copy(e, a)
	fmt.Println(e)
}

How to find out the data type?

// Figure out what type it is: maps, slices, or arrays!

package main

import (
	"fmt"
	"reflect"
)

func main() {

	// Declaring local variables
	map1 := map[string]string{"name": "John", "desc": "Golang"}
	map2 := map[string]int{"apple": 23, "tomato": 13}
	slice1 := []int{1, 2, 3}
	array1 := [3]int{1, 2, 3}
	// var m map[string]int
	// m = make(map[string]int)
	// More info Here: https://blog.golang.org/go-maps-in-action

	// Type, such as map[string]string, []int, [3]int
	fmt.Println("map1:", reflect.TypeOf(map1))
	fmt.Println("map2:", reflect.TypeOf(map2))
	fmt.Println("slice1:", reflect.TypeOf(slice1))
	fmt.Println("array1:", reflect.TypeOf(array1))

	// Value, such as map, slice, array.
	fmt.Println("map1:", reflect.ValueOf(map1).Kind())
	fmt.Println("map2:", reflect.ValueOf(map2).Kind())
	fmt.Println("slice1:", reflect.ValueOf(slice1).Kind())
	fmt.Println("array1:", reflect.ValueOf(array1).Kind())

	// True/False statement inside Printf
	fmt.Printf("%v is a map? %v\n", map1, reflect.ValueOf(map1).Kind() == reflect.Map)
	fmt.Printf("%v is a map? %v\n", map2, reflect.ValueOf(map2).Kind() == reflect.Map)
	fmt.Printf("%v is a map? %v\n", slice1, reflect.ValueOf(slice1).Kind() == reflect.Map)
}

In Go, the code does exactly what it says on the page.

It’s the simplicity that makes Go awesome.

Go: Statically typed yet expressive language with a focus on concurrency.

Go strives to keep things small and beautiful.

What I would have done in Python, Java, Ruby, PHP, C, C# or C++, I’m now doing in Go.

The code must be like a piece of music.

Code less, compile quicker, execute faster.

Any of your code that you haven’t looked at for 6 or more months may as well have been written by someone else.

General guideline: accept interfaces, return structs

Go is simple but not easy.

TODO :

• MongoDB connection
• MySQL connection
• Resize Images
• Set/Get Image tags
• SQLite connection
• Postgres connection
• React frontend