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-- this groups by 5 to keep the length down
select length(username) as length,
       count(*) as count,
       repeat('*'::text, (COUNT(length(username))::int / 5) + 1) AS histogram
from users
where username is not null
group by length(username)
order by length;

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Forms

Fill in inputs by name

# e.g.
# <table>
#   <tbody>
#     <tr>
#      <td><input name="foo" type="text" /></td>
#      <td><input name="bar" type="text" /></td>
# 

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CSVs

Generate a CSV

csv = CSV.generate(headers: true, force_quotes: true) do |row|
  row << ['ID', 'Name',  'Email']
  people.each do |person|
    row << [person.id, person.name, person.email]
  end
end
csv = "#{csv}" # Add BOM if people are going open this in Excel

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Introspection

List all indicies

The v query params shows the heading in the response

GET /_cat/indices?v

List indicies with wildcard

GET /_cat/indices/profiles*?v

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# config/initialers/generators.rb

# This config will not generate the following:
# - per model view helpers, or stylesheets
# - scaffold.scss
# - jbuilder templates, which I only occasionally use
# - controller tests, which I don't really use. I do system tests instead.


Rails.application.config.generators do |g|

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Get object count

$ aws s3 ls s3://<bucketname> --recursive | wc -l

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# frozen_string_literal: true

module UsesTempfile
  def with_tempfile(name: 'temp-zip-file', temp_dir: Rails.root.join('tmp').to_s, binmode: false)
    tempfile = Tempfile.new('temp-zip-file', temp_dir)
    tempfile.binmode if binmode
    
    yield tempfile
  ensure
    tempfile.close

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Migrating a Rails project from MySQL to PostgreSQL

This brief guide is written from my own experience with migrating a large (~5GB) MySQL database to PostgreSQL for a Rails project.

No warranties, guarantees, support etc. Use at your own risk and, as always, ENSURE YOU MAKE BACKUPS FIRST!

I chose [pgloader][1] because it's extremely fast. YMMV.

1. Replace mysql2 gem with pg in Gemfile.
2. Update config/database.yml for PostgreSQL. I used [Rails' template][2] as a starting point.

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const exportRows = [
  ["Name", "Email"],
  ["Foo Bar", "foo@bar.com"]
];

const csvContent = "data:text/csv;charset=utf-8," + exportRows.map((e) => e.join(",")).join("\n");
const encodedUri = encodeURI(csvContent);
const link = document.createElement("a");
link.setAttribute("href", encodedUri);
link.setAttribute("download", "export.csv"); // https://caniuse.com/#feat=download

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package com.solera.domain;

import com.opencsv.bean.CsvBindByName;

import java.util.Objects;

public class LogEntry {
    @CsvBindByName(column = "insertId")
    private String insertId;