div, change line code

whitespace-per-line

Read more

how to set file name when upload file,react

const modifiedFile = new File([file], "_icon.jpg", { type: file.type });

const formData = new FormData(); 

formData.append("file", modifiedFile);

Read more

javascript, join object array

objArray.map(obj=>obj.a).join(',')

- map

-join 

Read more

yarn uninstall

yarn remove xxx

yarn add xxxx

Read more

Docker not found when freshly installed on Mac

- Docker Desktop -> Settings -> Advanced -> Choose System, not User -> Click [Apply & restart]

Read more

Arrow function vs Function declaration

1. arrow function can not use this
2. arrow function must be defined before use
3. Function declaration can use new 

Read more

spring boot test,spring context

1. get value from application.yaml
1. use environment
2. use profile
3. @component
1. component scan 
2. initialize the component
3. add it to spring application context
4. can get the bean from application context
5. @Component equals @Bean in a @Configuration
4. can use @SpringBootTest to load spring application context 
2. 
   

Read more

after add ports to runing docker container

have to re-create container

docker-compose up -d --force-recreate xxx

Read more

git,commit,branch ,cherry-pick ,merge

• commit 
• is snapshot of all files
• not a change set
•  to store the hash ID of the latest commit in a branch name.
• branch name is just the lastest hash of commi branch name is just the lastest hash of commit
• In fact, this is the very definition of a branch name: a name like master simply stores the hash ID of the commit we want to call the latest for that branch. So given the A--B--C string of commits, we just add the name master, pointing to commit C:

• To remember which branch we want Git to update, as well as which commit we have checked-out right now, Git has the special name HEAD
• current branch
• A--B--C--D <-- develop (HEAD), master
• HEAD still names the current commit.
• A detached HEAD just means that Git has made the name HEAD point directly to some commit instead of attaching it to a branch name

• git merge
• git checkout master
• set HEAD to master
• git merge develop
• go backwards from master and develop, to find a shared base commit (祖先), called merge base
• The merge base commit is determined entirely by the commit graph,
• git diff baseCommint master  => get change set 1 
• git diff basecommit  develop   => get change set 2
• git combine the difference , use  a new commit id to save the result  ( merge commit )
• cherry-pick
• git diff somecommitId to get the change set
• just put the change on current commit(branch)
• but it maybe not works very well, git use cherry-pick-style merge, force the merge base commit to be the parent of the cherry-picked commit.
• cherry-pick create a new commit to save the result. 

•        G--H--F'   <-- master (HEAD)
        /
  ...--D
        \
         E--F   <-- develop

•  cherry-pick uses Git's merge machinery to do the change-combining, but leaves the graph unmerged, simply making a copy of some existing commit

• git merge somecommitid(branch)
• git merge -no-ff

Read more

postgres, golang , sqlx, placeholder, in

sql:  where some_id = any(:some_name)

golang, sqlx: 

 " some_name" :  pg.StringArray([]string )

Read more