how to serialise a javascript array to google flat buffers?

Question

I'm new to google flat buffers.

I am trying to serialise an array of objects in order to transfer it on the web using nodeJS.

first I created an fbs file and compile it with flatc:

namespace MyAlcoholist;

table Drink {
 drink_type_name: string;
 drink_company_name: string;
 drink_brand_name: string;
 drink_flavor_type_name : string;
 liquid_color_type_name : string;
 liquid_color_is_transparent : bool;
 alcohol_vol : float;
 calories_for_100g : uint;
 global_image_id: ulong;
 drink_flavor_id: ulong;
}

root_type Drink;

the compiler generated a file called drink_generated.js.

then I created the following utility module in Nodejs.

var flatbuffers = require('../js/flatbuffers').flatbuffers;
var builder = new flatbuffers.Builder(1);

var drink = require('../fbs/drink_generated').MyAlcoholist; // Generated by `flatc`.

function drinkArrayToIdl(drinkArray) {
drinkArray.forEach(function (element, index, array) {
    var drinkObj = element;
    drink.Drink.startDrink(builder);
    var drinkBrandName = builder.createString(drinkObj.drink_brand_name);
    var drinkCompanyName = builder.createString(drinkObj.drink_company_name);
    var drinkflavorTypeName = builder.createString(drinkObj.drink_flavor_type_name);
    var drinkTypeName = builder.createString(drinkObj.drink_type_name);
    var liquidColorTypeName = builder.createString(drinkObj.liquid_color_type_name);
    drink.Drink.addAlcoholVol(builder, drinkObj.alcohol_vol);
    drink.Drink.addCaloriesFor100g(builder,drinkObj.calories_for_100g);
    drink.Drink.addDrinkBrandName(builder,drinkBrandName);
    drink.Drink.addDrinkCompanyName(builder,drinkCompanyName);
    drink.Drink.addDrinkFlavorId(builder,drinkObj.drink_flavor_id);
    drink.Drink.addDrinkFlavorTypeName(builder, drinkflavorTypeName);
    drink.Drink.addDrinkTypeName(builder,drinkTypeName);
    drink.Drink.addGlobalImageId(builder,drinkObj.global_image_id);
    drink.Drink.addLiquidColorIsTransparent(builder,drinkObj.is_transparent);
    drink.Drink.addLiquidColorTypeName(builder,liquidColorTypeName);
    drink.Drink.endDrink(builder);
})
}

module.exports.drinkArrayToIdl=drinkArrayToIdl;

now based on https://google.github.io/flatbuffers/flatbuffers_guide_tutorial.html I need to close the buffer with builder.finish(var) and then to fetch the buffer with builder.dataBuffer().

I'm having a problem understanding what var do I need to provide to builder.finish(var)

I know that the function endDrink() returns the variable that I can call to close the buffer, but it's just for one Drink. I want to be able to insert many objects to that buffer.

is that possible? am I doing it right?

any information regarding the issue would be greatly appreciated.

Answer 1

Add a table Drinks { drinks:[Drink]; } and make that your new root_type. Then collect all return values of endDrink in a vector, and create a Drinks table with it.

Also, move all calls to createString before startDrink, as objects should not be nested.