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Android Clean Architecture

Creating the Projects Cache data source Implementation

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The Cache layer allows us to abstract the local source of data that our application uses. In this lesson, we're going to be creating the Projects Cache data source within the cache layer to allow us to provide cached data to parts of the project requesting it.

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I'm getting an error on the isProjectsCacheExpired function. Android Studio does not recognize the single() method. I've looked over my library refererences and I'm using all of the same version numbers as you are. I am using a newer version of Android Studio 3.2 Beta 5, but not sure that would cause the problem. Intellisense is trying to get me to use toSingle() which seems to work. Can you tell me what library is providing the single method? Perhaps it's been replaced by toSingle().

Also I'm confused by your 60 * 10 * 1000 code. What is this supposed to be determining? There are 86400000 milliseconds in a day.

I found the problem. When creating the configDao class, I entered the code as shown in the video which omitted a code change you made later. In the video you typed:

@Query(ConfigConstants.QUERY_CONFIG)
abstract fun getConfig(): Config

But the actual code was:

@Query(ConfigConstants.QUERY_CONFIG)
abstract fun getConfig(): Flowable

Once I fixed this the single method worked.

Thanks for spotting that Steve, I'll update the video :)

Same problem. Replaced with
.toSingle()
.map {
currentTime - it.lastCacheTime > expirationTime
}

But Im not sure if it's right.

and on the milliseconds, that is correct - it is just a representation of time. We state here that the cache is expired after a day!

I don't think you get what Steve is saying. (60 * 10 * 1000) != 1 day. The calculation should be (24 * 60 * 60 * 1000) == 1 day.

There is an error in code on video.

We are calling projectsDatabase.cachedProjctsDao().getBookMarkedProjects() in getProjects() instead of projectsDatabase.cachedProjctsDao().getProjects()

thanks - will get that updated!

Isn’t this class violating SRP? It is responsible i.a. for two pieces of logic: determining if project are cached and determining if cache has expired.

Well the purpose of this class is to handle the cache operations, so I would say this would fall under a sensible responsibility. If you wanted to follow that in that way, then this class would need to be split up quite a lot :)

>
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Lessons in Android Clean Architecture

Introduction to Clean Architecture
03:40
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Android and Clean Architecture
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Setting up a Multi-Module project
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Setting up the Domain layer module
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Creating the abstraction for our RxJava Observation Thread
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Setting up the Business Data for the Domain Layer
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Setting up the data access interface for the Domain Layer
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Setting up the Domain Layer Interactor classes
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03:28
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Implementing the Get Projects use case
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Implementing the get Bookmarked Projects use case
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Implementing the Bookmark Project use case
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Implementing the UnBookmark Project use case (Domain layer 8)
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02:03
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Testing the Get Projects use case
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02:41
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Testing the Get Bookmarked Projects use case
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02:04
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Testing the Bookmark Project use case
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02:10
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Testing the UnBookmark Project use case
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Setting up the data module
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Creating the data models for the data layer
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Creating the external source interfaces for our data layer
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02:24
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Creating the data layer store interface
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01:19
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Creating the data layer cache data store
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01:21
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Creating the data layer remote data store
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Creating the data store factory class
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Creating the central access point for the data layer
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03:00
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Setting up the tests for the Data Layer
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00:46
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Testing the data store factory class
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01:39
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Testing the project entity mapper
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01:18
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Testing the projects data repository
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06:02
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Testing the projects cache data store
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06:30
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Testing the projects remote data store
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02:17
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Setting up the remote module
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Creating the data models for the remote layer
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Creating the Retrofit Service for the remote data source
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Creating the Retrofit Service Factory for the remote service interface
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Creating the data model mapper for the Remote Layer
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Creating the Remote Source implementation
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Setting up the Remote layer for testing
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Testing the remote model mapper class
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Testing the remote source implementation
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Setting up the Cache module
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02:45
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Setting up the Cache layer data models
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02:02
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Creating the database for the cache layer
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01:34
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Creating the cached project Data Access Object
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02:42
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Creating the Configuration Data Access Object
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02:07
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Creating the cache model mapper
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02:06
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Creating the Projects Cache data source Implementation
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03:57
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Setting up the tests for our cache layer
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01:17
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Testing the cached project model mapper
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01:44
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Testing the Cached project DAO
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04:33
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Testing the Configuration DAO
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02:05
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Testing the projects cache implementation
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Setting up the presentation module
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Creating the data models for the presentation layer
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Creating the data model mapper for the presentation layer
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Creating the presentation state model
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Creating the browse projects view model
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Creating the bookmarked projects view model
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Setting up the presentation module tests
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02:09
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Testing the view model mapper
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01:17
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Testing our Browse Projects View Model implementation
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Testing our Browse Bookmarked Projects View Model implementation
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Setting up the UI module
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Creating the Post Execution Thread Implementation
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Setting up the application class
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Setting up the Dependency Injection for the UI module
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Creating the UI modules Project representation
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Creating the the Project model mapper for the UI module
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01:24
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Setting up the Browse Projects Activity
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01:08
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Configuring the DI for the project
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Creating the Project item view
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Creating the Browse Projects Adapter
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Creating the browse bookmarked projects adapter
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Creating the browse bookmarked projects activity
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Tying together the browse projects and bookmarked projects activity
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Setting up Unit Tests for the UI module
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Test the project model mapper
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Configuring the Dependency Injection for our User Interface tests
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Writing Espresso tests for the Browse Projects Activity
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Writing Espresso tests for the Bookmarked Projects Activity
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Simplifying the work we have done
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