Module 6 Introduction

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En provenance du cours de Johns Hopkins University

Capstone: Photo Tourist Web Application

18 notes

Johns Hopkins University

Capstone: Photo Tourist Web Application

18 notes

Cours 6 sur 6 dans Specialization Ruby on Rails Web Development

In this Capstone project for the Photo Tourist you will implement a Ruby on Rails web application that makes use of both a relational and NoSQL database for the backend and expose the data through services to the Internet using Web services and a responsive user interface operating in a browser from a desktop and mobile device. You will have a chance to revisit and apply what you have learned in our previous courses to build and deploy a fully functional web application to the cloud accessible to your co-workers, future employers, friends, and family. In developing the Photo Tourist web application, you will get to work with different data types and data access scenarios (e.g., fielded data display and update, image upload/download, text search, access controlled information) to provide your users the ability to show off their photos and information from trips they have taken and to seek out photos and information from trips taken by others. Using the application you develop, your users will be able to • Create an account • Upload and download photos to the site and make them accessible to others • Provide descriptions of trips and photos that others can read • Organize photos by location and trip, • Find photos based on location • Find photos based on text searches of descriptions • Locate the place where the photo was taken on a map

À partir de la leçon

Geolocation

In this module you will add geolocation capabilities to the end-to-end application. This will allow your users to assign a geolocation position to images as well as identify the current origin and distance limits for future API queries. You will implement the model and API queries for subjects within this module and complete the UI components within the next module. At the data tier you will add geolocation coordinates to the Image model, make those geolocation coordinates available to ThingImage though the 1:1 relationship between them, implement geolocation queries using the Geokit Rails gem that determine all items within a distance limit from an origin and supply their distance from origin. These queries will leverage custom SQL selects, joins (inner, right outer, and left outer join) and will be encapsulated within ActiveModel query scopes. At the API tier you will implement API service endpoints to geocode addresses and reverse geocode positions into a resolved location using the Geokit Rails gem and the Google Maps Geocode service, implement a persistence cache of geocode results using MongoDB to help stay within free service limits and speed up lookups, enable an API service endpoint to query for subjects (ThingImages) of a certain type, within a distance limit, and dynamically annotate them with the distance from the supplied origin, implement HTTP caching headers for both geocode and subject results. At the UI tier you will implement a geocoder service to lookup a location by (partial) address or position from the API implemented on the Rails server, add geocoding to the Image editor to allow a user to specify the Image's position using an address, build a current origin component to express and retain the center origin and distance limits for future subject queries.

Module 6 Introduction3:05

DB: Geolocation Coordinates4:51

DB: Image Position and Value Objects14:01

DB: Geolocation Queries with Geokit Rails14:19

DB: Associated Object Geolocation Queries13:08

DB: ThingImage Geolocation Query Scopes9:46

DB: PostalAddress and Location Value Objects7:34

Rencontrer les enseignants

Jim Stafford
Adjunct Professor, Graduate Computer Science
Computer Science, Whiting School of Engineering

[MUSIC]

Hi, welcome back.

Starting this module, we already have our images with content,

and our displays are starting to get somewhat interesting.

And in this module we're going to add geocoding to be able to add address

information to our images, so that we can start introducing the concept of distance.

At the model layer, we'll have some interesting work to do.

We'll start by adding longitude and

latitude to our images to support geolocation queries.

And we'll bring in the Geokit-Rails gem in order to implement those queries.

Finding things, what's the closest, what's within range.

And what is the distance of an image from an origin?

And then we'll take advantage of the relationship between thing image and

image, so that we can apply those same properties to our subjects.

And in this module, we'll also have another chance to have a deep dive down

into SQL and Query Scopes, and we'll take another look at joins.

We'll be leveraging inner joins, outer joins both left outer joins, and

right outer joins, as well as custom selects, and full custom queries.

When we reach the API layer, we'll add geocoding capabilities.

Or we'll go out to our provider,

and we'll geocode and address into a location with the position.

Or reverse geocode, a position into a location with an address.

And we'll use the Google Maps Geocode API in order to do that.

And we'll establish a free account.

And in order to stable those account thresholds,

we'll add a geocode cache on the backend, within our Rails server, using MongoDB.

At the functional level within the API,

we'll allow our users to add position to image, and to be able to locate subjects.

Thing images within a certain criteria.

Mainly distance, but type as well.

And we'll finish the API topics, adding an HTTP cache.

With cache control telling users how long they can keep

our answers before they have to come back and re-validate them.

And e-tags, knowing when the answer is still current.

At the UI layer, we'll be focusing on the geocoding and

reverse geocoding aspects of taking addresses and

turning them into positions, or positions and turning them into addresses.

And we'll create a service that'll interact with the back end, and

work with the caching layer, and we'll reuse that service in at least two places.

One, we'll allow users to add position to their images.

And two, we'll add a component to our Navbar that'll be responsible for

taking the user expression of current origin, and

storing that in a service that will become the rallying point for various components

to begin showing the user a view of what they are currently interested in.

So this module is all about establishing location and

distances between the images at certain locations.

So the user has the ability to determine what is close to them and far, and

make choices of what they want to get to.

Okay, let's get started.

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