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Sometimes we need to extract part of the SVG from a PNG image. This post will show how to do it with Inkscape. I will take the Filebase logo as an example. Remove the white background Open the graphic software Greenfish Icon Editor Drag the .png file into the software Fill the colorful part with the black color Apply the white background to transparent with the color picker setting on the right bottom Save it as a png file with the original resolution Convert the png file to svg file Open the graphic software Inkscape Drag the previous .png file into the software Place the image at (0,0) Record the original width and height in specific unit Go to the Document Properties... in the File menu or press Shift+Ctrl+D, and edit the width and height as recorded previous and tick the Checkerboard background option Save the file as a plain svg format

Passing the JSON argument via the Command-line flag seems to be not typical, but we may need it in some cases. This post will show you how to implement it in Golang. The package flag provides an easy way to implement it. Let’s take a look at a simple example of using package flag first: package main import ( "flag" "fmt" ) func main() { var version string // parse the value of the flag setVersion to variable version flag.StringVar(&version, "setVersion", "1.0.0", "") flag.Parse() fmt.Println("version = ", version) } The output is ...

This is a collection of useful PostgreSQL commands and snippets that I have used in the past. It will be continuously updated. ❗ How to execute psql commands in PostgreSQL docker container # List all running containers to find your Postgres container name or ID docker ps # Open an interactive shell inside the Postgres container docker exec -it postgres_db bash # Log in to PostgreSQL as the 'postgres' user psql -U postgres # List all databases in the PostgreSQL server \l # Connect to a specific database \c your_database_name # List all tables in the connected database \dt # Display all records from the specified table SELECT * FROM your_table_name; # Display the first 10 records from the table (optional) SELECT * FROM your_table_name LIMIT 10; # Show the structure (columns, types, indexes) of the table \d your_table_name # Toggle expanded view for better readability of wide rows \x # Exit the PostgreSQL prompt \q # Exit the container shell exit # (Alternative: run a one-liner query directly from your host) # Run SQL query without entering the container docker exec -it postgres_db psql -U postgres -d your_database_name -c "SELECT * FROM your_table_name LIMIT 10;" 1. Init a database sudo su postgres psql create database osmapi create user osmapi \password osmapi grant all privileges on database "osmapi" to osmapi \c osmapi create extension "uuid-ossp" create extension cube create extension earthdistance 2. Duplicate a table create table dupe_users as (select * from users); create table dupe_users as (select * from users) with no data; 3. Change the owner of a table and view ALTER TABLE public.tablename OWNER TO my_user; ALTER VIEW latest_status_logs OWNER TO my_user; 4. Drop a column ALTER TABLE tablename DROP COLUMN category_id; 5. Install “uuid-ossp” apt-get install postgresql-contrib-9.3 6. Check index SELECT * FROM pg_indexes WHERE TABLENAME NOT LIKE 'pg%' DROP INDEX xxx alter table activity_auditings drop constraint activity_auditings_extra_curriculum_no_key 7. Connect to the remote database by CLI psql -d mydb -U myuser psql -h myhost -d mydb -U myuser psql --host=dataant-test.cpkuy5lqfq7v.ap-southeast-2.rds.amazonaws.com \ --port=5432 \ --username=dataanttest \ --password \ --dbname=dataantapi 8. Change a column name ALTER TABLE client_profiles RENAME COLUMN user_id TO profile_id 9. Install Postgres sudo apt-get update sudo apt-get install postgresql postgresql-contrib 10. Set the access permission of other machines /etc/postgresql/9.1/main/pg_hba.conf # ipv4 host all all 0.0.0.0/0 md5 (e.g. 192.168.0.0/16) host all all 192.168.239.133/16 md5 /etc/postgresql/9.1/main/postgresql.conf listen_address='*' Restart database ...

Introduction Although the problem is categorized as “EASY” in terms of difficulty, I must admit that the solution didn’t immediately come to mind after reading the description. Nevertheless, I managed to find a straightforward and concise approach that is both easy to comprehend and implement. I won’t explain the requirement here, so before reading the below explanation, I highly suggested that making sure we understand this problem’s description. The challenge description can be found https://www.hackerrank.com/challenges/flatland-space-stations/problem ...

This post is about how to use reflect feature to implement as much as you want to do with Golang. Here are some cases: 1. How to get all the fields’ name of an object? 1type A struct{ 2 Foo string 3 Bar int64 4} 5 6func main() { 7 a := &A{Foo: "afoo"} 8 val := reflect.ValueOf(a).Elem() 9 for i:=0; i<val.NumField();i++{ 10 fmt.Println(val.Type().Field(i).Name) 11 } 12} The output: ...