TIL

Rails logs your server’s activity, which is useful for development and debugging. However, often the server handles sensitive information that should not be logged. A few examples are authentication credentials, personal data, and financial information. To prevent Rails from logging such data, add this to your application configuration: config.filter_parameters << :sensitive_param When the named parameter is handled by the server, it will be logged as [FILTERED] instead of its actual value. Add this configuration by environment if you want to keep the parameters unfiltered in development.

In this example, we want to allow users to enter a twitter handle with or without an at-sign (’@’), just like Twitter, but save it without the at-sign. twitter_handle is already an attribute on the class. class User < ActiveRecord::Base def twitter_handle=(handle) write_attribute(:twitter_handle, handle.to_s.gsub(/^@/, '')) end end

git reflog is a record of your actions in Git. With this command, you can undo almost any Git mistake. $ git reflog 4bd0090 HEAD@{0}: <bad place> 46bd839 HEAD@{1}: <bad place> 967e214 HEAD@{2}: <last good place> 46bd839 HEAD@{3}: <good place> 967e214 HEAD@{4}: <good place> $ git reset --hard HEAD@{2}

:g/^\s*#/d will remove comment lines from a file with Vim.

While in less (terminal pager program), h or H brings up a summary of commands.

Apply a Patch in Reverse Need to undo a code change? You could revert. Or, you could apply the patch without creating a commit. That’s what I want to do much of the time. Use git apply with the -R (reverse) flag: git show 8cc13b1 | git apply -R All the changes from 8cc13b1 get applied to your working directory. In a large commit, do this tactically by limiting to just one file or directory. ...

Clear React Router’s Location State From the Console The return of React Router’s useLocation hook has a key called state which contains values passed during a redirect or navigation. But where is that state stored by the browser, and how do we clear it? I found it in Chrome on window.history.state: > window.history.state < { "usr": { "pageTitle": "Redirected!" }, "key": "31ytq582", "idx": 4 } And cleared it using replaceState: > window.history.replaceState({}, '') < undefined > window.history.state < {} Window.history docs

Either/Or Props in TypeScript Sometimes in TypeScript we’d like to say a function can either have one typed prop, or the other, never both and never neither. This can be achieved with a union type and type never: type Props = { markdown: string, copy?: never } | { markdown?: never, copy: string} }; const component = ({ markdown, copy }: Props) => markdown ? parseMarkdown(markdown) : <>copy</>; console.log(component({ markdown: "### Important" })) // <h3>Important</h3> console.log(component({ copy: "Just information" })) // <>Just information</> console.log(component({ copy: "Just information", markdown: "### That conflicts })) // ❌ Type error console.log(component({})) // ❌ Type error Our component can receive a string of markdown, which it will parse, or raw copy, which it will not parse. Always just one, never both, and never neither.

Encoding Plus Signs in URLS If you’re creating a hyperlink with query params, and those param values can have plus signs, it’s important to encode them values. We do this with encodeURIComponent: const email = `jake+testing@example.com` const loginLink = `https://example.com/login?email=${encodeURIComponent(email)}` window.open(loginLink) If you skip this step and try to read the query parameters received by ’example.com’ your email param value may be interpreted as with spaces instead of pluses, i.e. jake testing@example.com. Per the docs: Within the query string, the plus sign is reserved as shorthand notation for a space. Therefore, real plus signs must be encoded. This method was used to make query URIs easier to pass in systems which did not allow spaces. ...