gopgpager

gopgpager

go-pg (https://github.com/go-pg) cursor pagination

Installation

$ go get github.com/SramPay/gopgpager

Usage

First, import the package:

import "github.com/SeamPay/gopgpager"

Now, you can access the package through gopgpager namespace.

• CursorPaginator: uses a database condition Where("(id, created_at) <= (?, ?)", id, createdAt).

It works in four steps:

• Create a store (go-pg)
• Create a CursorPaginator instance with: your store, and the request

req := pagination.Request{
    PageToken: pageToken, // string
	PageSize:  pageSize, // int32
}

// pageToken is a base64 encoded comma separated string made up the id and createdAt
// pageSize the amount of records to return

• Call the paginator.Page() method to process the pagination
• Call the paginator.Next() method to get the next paginator instance

Example:

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

CREATE TABLE IF NOT EXISTS users
(
    id                  uuid      NOT NULL DEFAULT uuid_generate_v4()
        CONSTRAINT users_pkey
            PRIMARY KEY,
    created_at          TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at          TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    first_name          VARCHAR   NOT NULL,
    last_name           VARCHAR   NOT NULL,
);

-- the order of columns is important. If you reverse it, the index will not be useful. 
CREATE INDEX created_at_id_idx ON customers (created_at, id);

// create a slice for your go-pg entity.
var users []entity.User

// create the store. It takes your database connection pointer,
// and a pointer to entity.
store, err := gopgpager.NewGOPGStore(&db, &users)
if err != nil {
	log.Fatal(err)
}

// create the query request
req := pagination.Request{
	PageToken: "", // first request has no token
	PageSize:  1,
}

// create a paginator instance and pass your store, your request
paginator, err := gopgpager.NewCursorPaginator(store, req)
if err != nil {
	log.Fatal(err)
}

// call the paginator.Page() method to get the page instance.
err = paginator.Page()
if err != nil {
	return nil, "", err
}

// paginator instance contains everything you need.
paginator.Limit
paginator.NextToken.String // set to pageToken on the request

// get the next page.
nextPaginator, err := paginator.Next()
if err != nil {
	log.Fatal(err)
}

Contributing

• Fork the project
• Fix bugs