🌱

Author: mars

.gitignore

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+/target/
+**/*.rs.bk

Cargo.lock

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+[package]
+name = "diesel-pg-timestamp-usage"
+version = "0.1.0"
+authors = ["Mars Hall"]
+
+[dependencies]
+chrono = "0.4.0"
+diesel = { version = "1.0.0", features = ["chrono", "postgres"] }

Cargo.toml

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+# Timestamps with Diesel.rs & Postgres
+
+Example using UTC timestamps with the Rust language database ORM [Diesel](https://diesel.rs).
+
+🌱💚 *Please note, I am new to Rust. I could not find a clear example for this basic task, so here's what I figured out. No guarantees about correctness. Please [open an issue](https://github.com/mars/diesel-pg-timestamp-usage/issues) to give feedback. I'd love to find better ways to do this.* 
+
+## Requirements
+
+* [Rust + Cargo](https://www.rust-lang.org)
+* [Postgres](https://www.postgresql.org/download/)
+* `cargo install diesel_cli`
+
+## Usage
+
+```bash
+export DATABASE_URL=postgres://postgres@localhost:5432/diesel-pg-timestamp-usage
+diesel setup
+cargo run
+```
+
+## Original setup
+
+```bash
+export DATABASE_URL=postgres://postgres@localhost:5432/diesel-pg-timestamp-usage
+diesel setup
+diesel migration generate create-example
+# Write code in `migrations/up.sql` & `down.sql`
+diesel migration run
+diesel migration redo
+diesel print-schema > src/schema.rs
+```

README.md

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+-- This file was automatically created by Diesel to setup helper functions
+-- and other internal bookkeeping. This file is safe to edit, any future
+-- changes will be added to existing projects as new migrations.
+
+DROP FUNCTION IF EXISTS diesel_manage_updated_at(_tbl regclass);
+DROP FUNCTION IF EXISTS diesel_set_updated_at();

migrations/.gitkeep

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+-- This file was automatically created by Diesel to setup helper functions
+-- and other internal bookkeeping. This file is safe to edit, any future
+-- changes will be added to existing projects as new migrations.
+
+
+
+
+-- Sets up a trigger for the given table to automatically set a column called
+-- `updated_at` whenever the row is modified (unless `updated_at` was included
+-- in the modified columns)
+--
+-- # Example
+--
+-- ```sql
+-- CREATE TABLE users (id SERIAL PRIMARY KEY, updated_at TIMESTAMP NOT NULL DEFAULT NOW());
+--
+-- SELECT diesel_manage_updated_at('users');
+-- ```
+CREATE OR REPLACE FUNCTION diesel_manage_updated_at(_tbl regclass) RETURNS VOID AS $$
+BEGIN
+    EXECUTE format('CREATE TRIGGER set_updated_at BEFORE UPDATE ON %s
+                    FOR EACH ROW EXECUTE PROCEDURE diesel_set_updated_at()', _tbl);
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION diesel_set_updated_at() RETURNS trigger AS $$
+BEGIN
+    IF (
+        NEW IS DISTINCT FROM OLD AND
+        NEW.updated_at IS NOT DISTINCT FROM OLD.updated_at
+    ) THEN
+        NEW.updated_at := current_timestamp;
+    END IF;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;

migrations/00000000000000_diesel_initial_setup/down.sql

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+DROP TABLE IF EXISTS examples

migrations/00000000000000_diesel_initial_setup/up.sql

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+CREATE TABLE examples (
+  id serial primary key,
+  created_at timestamp not null,
+  updated_at timestamp
+)

migrations/2018-02-04-184819_create-example/down.sql

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+extern crate chrono;
+#[macro_use]
+extern crate diesel;
+
+use chrono::prelude::{Utc};
+use diesel::prelude::*;
+use diesel::pg::PgConnection;
+use std::env;
+
+pub mod schema;
+pub mod models;
+use self::models::{Example, NewExample};
+
+fn main() {
+    let postgres_url = env::var("DATABASE_URL")
+        .expect("requires DATABASE_URL env var");
+    let pg = PgConnection::establish(&postgres_url)
+        .expect(&format!("Error connecting to {}", postgres_url));
+
+    let now = Utc::now().naive_utc();
+
+    let new_example = NewExample {
+        created_at: now,
+        updated_at: Some(now),
+    };
+
+    let database_record = diesel::insert_into(schema::examples::table)
+        .values(&new_example)
+        .get_result::<Example>(&pg)
+        .expect("Error saving new example");
+
+    println!("Inserted example: {:?}", database_record);
+}

migrations/2018-02-04-184819_create-example/up.sql

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+use super::schema::examples;
+use super::chrono;
+
+#[derive(Insertable, Debug)]
+#[table_name="examples"]
+pub struct NewExample {
+    pub created_at: chrono::NaiveDateTime,
+    pub updated_at: Option<chrono::NaiveDateTime>,
+}
+
+#[derive(Queryable, Debug)]
+pub struct Example {
+    pub id: i32,
+    pub created_at: chrono::NaiveDateTime,
+    pub updated_at: Option<chrono::NaiveDateTime>,
+}

src/main.rs

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+table! {
+    examples (id) {
+        id -> Int4,
+        created_at -> Timestamp,
+        updated_at -> Nullable<Timestamp>,
+    }
+}