# README

Golang Mongo Pagination For Package mongo-go-driver

For all your simple query to aggregation pipeline this is simple and easy to use Pagination driver with information like Total, Page, PerPage, Prev, Next, TotalPage and your actual mongo result.

Install

$ go get -u -v github.com/gobeam/mongo-go-pagination

or with dep

$ dep ensure -add github.com/gobeam/mongo-go-pagination

For Aggregation Pipelines Query

package main

import (
	"context"
	"fmt"
	. "github.com/gobeam/mongo-go-pagination"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"time"
)

type Product struct {
	Id       primitive.ObjectID `json:"_id" bson:"_id"`
	Name     string             `json:"name" bson:"name"`
	Quantity float64            `json:"qty" bson:"qty"`
	Price    float64            `json:"price" bson:"price"`
}

func main() {
	// Establishing mongo db connection
	ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
	client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://localhost:27017"))
	if err != nil {
		panic(err)
	}
	
	var limit int64 = 10
	var page int64 = 1
	collection := client.Database("myaggregate").Collection("stocks")

	//Example for Aggregation

	//match query
	match := bson.M{"$match": bson.M{"qty": bson.M{"$gt": 10}}}

	//group query
	projectQuery := bson.M{"$project": bson.M{"_id": 1, "qty": 1}}

	// you can easily chain function and pass multiple query like here we are passing match
	// query and projection query as params in Aggregate function you cannot use filter with Aggregate
	// because you can pass filters directly through Aggregate param
	aggPaginatedData, err := New(collection).Limit(limit).Page(page).Sort("price", -1).Aggregate(match, projectQuery)
	if err != nil {
		panic(err)
	}

	var aggProductList []Product
	for _, raw := range aggPaginatedData.Data {
		var product *Product
		if marshallErr := bson.Unmarshal(raw, &product); marshallErr == nil {
			aggProductList = append(aggProductList, *product)
		}

	}

	// print ProductList
	fmt.Printf("Aggregate Product List: %+v\n", aggProductList)

	// print pagination data
	fmt.Printf("Aggregate Pagination Data: %+v\n", aggPaginatedData.Data)
}

For Normal queries



func main() {
	// Establishing mongo db connection
	ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
	client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://localhost:27017"))
	if err != nil {
		panic(err)
	}

	// Example for Normal Find query
    	filter := bson.M{}
    	var limit int64 = 10
    	var page int64 = 1
    	collection := client.Database("myaggregate").Collection("stocks")
    	projection := bson.D{
    		{"name", 1},
    		{"qty", 1},
    	}
    	// Querying paginated data
    	// Sort and select are optional
    	paginatedData, err := New(collection).Limit(limit).Page(page).Sort("price", -1).Select(projection).Filter(filter).Find()
    	if err != nil {
    		panic(err)
    	}
    
    	// paginated data is in paginatedData.Data
    	// pagination info can be accessed in  paginatedData.Pagination
    	// if you want to marshal data to your defined struct
    
    	var lists []Product
    	for _, raw := range paginatedData.Data {
    		var product *Product
    		if marshallErr := bson.Unmarshal(raw, &product); marshallErr == nil {
    			lists = append(lists, *product)
    		}
    
    	}
    	// print ProductList
    	fmt.Printf("Norm Find Data: %+v\n", lists)
    
    	// print pagination data
    	fmt.Printf("Normal find pagination info: %+v\n", paginatedData.Pagination)
}