Category: Development

Add a composite constraint and view it, MySQL/MariaDB

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Add

Adding constraint NetAppToken composing of 3 columns: network, application, token.
Note: you supposed to have chosen a right db:
use <database_name>;

ALTER TABLE crypto   
    ADD CONSTRAINT NetAppToken UNIQUE (network, application, token);

View

SELECT 
   table_schema,  
   table_name,    
   constraint_name
FROM information_schema.table_constraints
WHERE table_name = 'crypto';

Result

+--------------+------------+-----------------+
| table_schema | table_name | constraint_name |
+--------------+------------+-----------------+
| admin_crypto | crypto     | PRIMARY         |
| admin_crypto | crypto     | NetAppToken     |
+--------------+------------+-----------------+
2 rows in set (0.06 sec)

Post author By Igor Savinkin
Post date December 24, 2021

Development

CURL request into Curl PHP code

Recently I needed to transform the CURL request into the PHP Curl code, binary data and compressed option having been involved. See the query itself:

curl 'https://terraswap-graph.terra.dev/graphql' 
-H 'Accept-Encoding: gzip, deflate, br' 
-H 'Content-Type: application/json' 
-H 'Accept: application/json' 
-H 'Connection: keep-alive' 
-H 'DNT: 1' 
-H 'Origin: https://terraswap-graph.terra.dev' 
--data-binary '{"query":"{\n  pairs {\n    pairAddress\n    latestLiquidityUST\n    token0 {\n      tokenAddress\n      symbol\n    }\n    token1 {\n      tokenAddress\n      symbol\n    }\n    commissionAPR\n    volume24h {\n      volumeUST\n    }\n  }\n}\n"}' 
--compressed

Post author By Igor Savinkin
Post date December 22, 2021

Development

Auth proxy with JAVA

Tags JAVA
No Comments on Auth proxy with JAVA

In the post we’ll show how to leverage auth ptoxy (with login/pass) for JAVA application.

Post author By Igor Savinkin
Post date November 29, 2021

Development

Vesta CP install SSL certificate for a subdomain

In this post I’ll share how I’ve added a LetsEncrypt SSL certificate to a subdomain at VPS with Centos 7 using Vesta CP.

Post author By Igor Savinkin
Post date November 16, 2021

Development

Subdomain at Centos 7 with Laravel project

This post is devoted to the steps of how to create subdomain (Centos 7 and Vesta CP) and map a [Laravel] project folder to it.

Post author By Igor Savinkin
Post date November 11, 2021

Development

How to add Git Personal Access Token (PAT) into git console

No Comments on How to add Git Personal Access Token (PAT) into git console

Remove previous git origin

git remote remove origin

Add new origin with PAT (<Token>) :

git remote add origin https://<TOKEN>@github.com/<USERNAME>/<REPO>.git

Push once with –set-upstream

git push --set-upstream origin main

Now you might commit changes to the remote repo without adding PAT into a push command every time.

If you need to create PAT, use the following tut.

Post author By Igor Savinkin
Post date October 1, 2021

Development

Cheerio.js, get items from html table into object

Suppose there is a table like below (1 info row only):

Blows Minute (BPM)	Speed (RPM)	Power, PSI	Flow, PSI	Tool Sys
0-2500	0-250	1.8 HP	2.6-13.2 GPM	SDS Max

How to scrape it using cheerio.js as a parser?

Case 1 (1 row only)

Post author By Igor Savinkin
Post date April 16, 2021

Development

Redirect Node.js console output into file

node.exe index.js > scrape.log 2>&1

When executing file index.js we redirect all the console.log() output from console into a file scrape.log .

Post author By Igor Savinkin
Post date March 22, 2021

Development

Remove empty html tags recursively

Sometimes we have the code with html tags that contain nothing but whitespace characters. Often those tags are nested. See a code below:

<div> 
 <div> 
  <div></div> 
 </div> 
</div>

What regex might be used to find and remove those tags?

Obvious solution is <div>\s*?<\/div> .

\s stands for “whitespace character”. It includes [ \t\n\x0B\f\r]. That is: \s matches a space( ) or a tab (\t) or a line(\n) break or a vertical tab (\x0B) sometimes referred as (\v) or a form feed (\f) or a carriage return (\r) .

General case

In general case, we use the following regex:
<(?<tag>[a-z]+?)( [^>]+?|)>\s*?<\/(\k<tag>)>

where <tag> is a named match group: [a-z]+?

JAVA code

When applying it recursively we might use the following code, JAVA:

public static String removeEmptyTags(String html) {
        boolean compareFound = true;
        Pattern pattern = Pattern.compile("<(?<tag>[a-z]+?)( [^>]+?|)>\\s*?</(\\k<tag>)>", Pattern.MULTILINE | Pattern.DOTALL);
        while (compareFound) {
            compareFound = false;
            Matcher matcher = pattern.matcher(html);
            if(matcher.find()) {
                compareFound = true;
                html = matcher.replaceAll("");
            }
        }
        return html;
    }

Post author By Igor Savinkin
Post date March 19, 2021