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Showing 631–660 of 770 public snippets

Go
sql.NullString — Nullable DB Columns
Plain `string` can't represent SQL NULL. Use `sql.NullString` (and its siblings `NullInt64`, `NullBool`, etc.) for columns where NULL is a real value distinct from empty.
3h ago 0
SQL
SELECT DISTINCT and Counting Uniques
`DISTINCT` removes duplicate rows. Combine with `COUNT(DISTINCT col)` to count uniques in aggregations — different from `COUNT(*)`.
3h ago 0
SQL
EXTRACT — Pull Parts Out of a Timestamp
`EXTRACT(field FROM timestamp)` pulls year, month, hour, day-of-week, week, epoch — whatever you need to group, filter, or render. Standard SQL across every database.
3h ago 0
Rust
Move vs Borrow — the Core Rule
Rust's ownership model: passing a value transfers ownership (move); taking a `&value` lets you read without taking ownership; `&mut value` lets you modify without taking ownership. Only one mutable borrow OR many immutable borrows at a time.
3h ago 0
Rust
Serde — Field Rename, Skip, and Tagging
Per-field attributes let you map between Rust's snake_case and the JSON's camelCase, skip optional fields, and tag enum variants the way external APIs expect.
3h ago 0
Kotlin
Result Type — Safe Error-Returning APIs
`Result<T>` wraps "success or thrown exception" without forcing the caller into try/catch. `runCatching { ... }` is the standard producer.
3h ago 0
PHP
Sort by Multiple Keys
Stable multi-column sort for arrays of associative rows. Each column can be sorted ASC or DESC independently. Wraps usort with a chained comparator.
3h ago 0
PHP
PDO Connection with Sensible Defaults
Open a PDO connection with all the options you almost always want: real prepared statements, exceptions on error, associative-array fetch mode, UTF-8 charset.
3h ago 0
Python
Mask Sensitive Strings (PII)
Mask the middle of a string while keeping a few chars at each end. Useful for displaying credit cards, emails, or API keys in UI / logs without leaking the whole value.
3h ago 0
Rust
Untyped JSON with serde_json::Value
When you don't know the JSON shape up-front, parse into `serde_json::Value` and navigate via index / get(). Type-safe pattern matching converts back to Rust types.
3h ago 0
Java
java.time — Format and Parse
`DateTimeFormatter` replaces `SimpleDateFormat` (which was not thread-safe). Constants for the common formats; pattern strings for custom layouts.
3h ago 0
HTML
Radio Group with Fieldset + Legend
Always wrap radio groups (and checkboxes that share semantics) in a `<fieldset>` with a `<legend>`. Screen readers announce the legend before each option — without it, the choice is contextless.
3h ago 0
HTML
Picture Element — Art Direction
`<picture>` lets you serve DIFFERENT images at different breakpoints — not just different sizes of the same crop. Perfect for a wide desktop banner that becomes a square mobile poster.
3h ago 0
PHP
Convert Timestamp to User Timezone
Convert a stored UTC timestamp into the viewer's timezone for display. Round-trip safe: re-converting to UTC always gives back the original timestamp.
3h ago 0
PHP
Build WHERE IN with Placeholders
Safely interpolate a variable-length list into a "WHERE col IN (...)" clause. Returns the SQL fragment plus the bound parameters — never concatenate user values into SQL.
3h ago 0
TypeScript
Template Tag for Safe HTML
Build HTML strings with a tagged template literal that auto-escapes every interpolated value. Eliminates a class of XSS bugs without pulling in a templating library.
3h ago 0
Python
Stream-Download Large File with Progress
Download a file in chunks so memory stays flat regardless of file size, with a tqdm progress bar showing speed + ETA. Skips re-download if the file is already complete.
3h ago 0
Rust
macro_rules! — Simple Declarative Macros
Declarative macros let you write functions that take token trees instead of values. Great for boilerplate reduction; cleaner than copy-paste, simpler than proc macros.
3h ago 0
Java
Sorting with Comparator
`Comparator.comparing`, `thenComparing`, and `reversed()` chain into expressive multi-field sorts. Way cleaner than the old Comparable spaghetti.
3h ago 0
Java
HttpClient — Synchronous GET (Java 11+)
`java.net.http.HttpClient` ships in the JDK — no Apache HttpClient or OkHttp needed for most cases. Reuse one client across the app; configure timeouts and follow-redirects up front.
3h ago 0
SQL
JSONB Columns (PostgreSQL)
`jsonb` stores binary-optimized JSON. Index sub-fields with GIN for fast containment queries. Most-used operators: `->` (get field), `->>` (get as text), `@>` (contains), `?` (key exists).
3h ago 0
PHP
Validate Uploaded File
A defense-in-depth check for $_FILES uploads: confirms the upload completed, the size is within bounds, the MIME type matches an allow-list (by libmagic, not by extension), and the file landed where PHP expected.
3h ago 0
PHP
UPSERT (INSERT ... ON DUPLICATE KEY UPDATE)
A MySQL upsert helper: insert a row, or if a unique key collides, update the same row with the new values. Returns whether the row was inserted (true) or updated (false).
3h ago 0
TypeScript
Result / Either Type
Encode "this might fail" in the type signature instead of throwing. Force the caller to handle both branches at compile time. Better than try/catch for foreseeable failures.
3h ago 0
TypeScript
partition — Split by Predicate
Split an array into [pass, fail] in a single pass. Type guard overload lets the truthy bucket get a narrowed type when you pass a `x is T` predicate.
3h ago 0
TypeScript
Format Relative Time ("3 days ago")
Use the built-in Intl.RelativeTimeFormat to render "3 days ago" / "in 5 hours". Localized for free — pass any BCP 47 locale. No date library needed.
3h ago 0
Python
Sliding Window Iterator
Iterate over an iterable with a rolling window of N items. itertools.batched (Python 3.12+) gives you NON-overlapping chunks; this helper gives overlapping ones, common for moving averages or n-gram analysis.
3h ago 0
Python
Bulk Insert with executemany
Insert many rows in one round-trip using executemany. Orders-of-magnitude faster than a loop of single inserts — and the driver handles batching/parametrization for you.
3h ago 0
Bash
Split String into Array on Delimiter
Use IFS + read or readarray to split safely. Don't use word-splitting tricks — they break on edge cases (empty fields, spaces in values).
3h ago 0
Bash
Days Between Two Dates
Convert both dates to epoch seconds, subtract, divide. Works for hours/minutes too with the obvious divisor.
3h ago 0