Category

Database

This topic is going to be sort of continuation of my previous post about SQLiteWrapperUWP-PCL – an SQLite Wrapper for Windows 10 UWP applications. I’m writing “sort of” because it’s actually an update to that post. The project part – setting up the solution – hasn’t changed but the code part has. Please understand that the SQLiteWrapperUWP-PCL library is being constantly developed and improved, hence I need to explain how things has changed and how one should implement their database logic with latest release of SQLiteWrapperUWP-PCL NuGet package BuildIt SQLite.

For those who are not very familiar with Windows 10 and UWP application development please, before you start going through what’s written in here, refer to my previous post about SQLite Wrapper for Windows 10 UWP applications, where you can find guidelines how to set up your solution / project.

For those who can’t be bothered reading and/or want to figure things out by themselves I recommend looking at the GitHub repository GitHub repository where you can find some short guidance / information about how things work with SQLiteWrapperUWP-PCL BuildIt (Sqlite). Also there’s a CRUD database operations example CRUD database operations example which could be a good place to start your explorations.

EDIT: Apologies to all that wanted to try out the SQLiteWrapperUWP-PCL and some of the links weren’t working, but SQLiteWrapperUWP-PCL evolved from its own existence, to become a part of a bigger set of libraries, called BuildIt. Those libraries are a foundation that we rely on, in almost every project that we create @BuiltToRoam, so besides working with SQLite check out others, I can bet you will like it and use it.

The Code

Let’s start from the Core project and setting up the DatabaseService.

The base class, that DatabaseService inherits from, is an abstract class BasicDatabaseService which is a exemplary implementation of BaseDatabaseService. Both of which sit in the SQLiteWrapperUWP-PCL library and expose the IBasicDatabaseService and IBaseDatabaseService interfaces. In this case, deriving from Basic service, one have to provide only the implementation of CreateDatabaseTables method, which is responsible for creating database tables, and provide some constructor parameters, about which in a second.

I think it’s worth noting that one is left with an option to derive directly from BaseDatabaseService and in that case it opens a path where one could provide their own SQLite database connection creation (implement CreateSQLiteConnection method) handling.

Let’s explain a bit about DatabaseService constructor parameters and its purpose.

  • ISqlitePlatformProvider consists of one child, and its purpose is to provide core SQLite platform functionality, basically it’s the “heart” or “spine” to the SQLite database.
  • IDatabaseNameProvider is nothing more but a “fancy” way of saying “if you want a database you need to give it a name it”. With this interface implementation you need to provide a database name, and that’s it – one string
  • Last but not least is the ILocalFileService which is necessary to provide a way of getting physical path – RetrieveNativePath method – where the database file will be saved (on a hard drive)

You can find exemplary implementation of all of those in the GitHub repository

NOTE: In almost all of my projects I use mvvm cross-platform framework MvvmCross, which I highly recommend, and with it, out of the box, comes Dependency Injection (IoC) mechanisms. Those mechanism under the hood, create and inject automatically singletons for mentioned above interfaces (constructor parameters). You can find out more about it in the N+1 days of MvvmCross blog posts and videos. For those who are familiar with it and to spare you some time looking for how it could be initialized, here’s a sample code from Setup.cs file

 

Important thing, that has been changed in the latest release, is BaseEntity class. It was redesign to consists the update of representation of the entity logic (update of the database record). For example:

There’re two things to note in the above code. First is to do with self-reference generic class in the class declaration. It was purely designed this way so we could handle the update logic inside of the Entity class, which is called from the BaseRepository every time the Update logic on the entity is executed. UpdateFromEntity method – second thing that one should be aware of – should be a place where entity update is being handled.

 

Assuming you have an instance of DatabaseService handy (e.g. created with MvvmCross DI mechanisms) and with all this setup / knowledge we can now start working with our database, and it couldn’t be any easier. To create new database record (entity) one could write something as follows:

To retrieve all the table records or just one:

To delete record:

Those are Base CRUD methods, but if you’d like to write more sophisticated queries you should look into BaseRepository and Table property. It will allow you to perform some LINQ queries on it. For example:

NOTE: As it’s not perfectly obvious, the CreateSQLiteConnection method won’t create a new one every time it’s being called, but it will take the cached one.

NOTE: Another thing is that not all LINQ queries will be valid in terms of translating them to what database understands, hence sometimes it’s better to grab all table records (entities) and perform some queries on the values stored in memory.

 

I would highly recommend checking out the GitHub repository and the sample that is in it, as it consists all of what I’ve just wrote about, and you can easily compile and debug that code.

 

NOTE: For inspecting SQLite database file(s) I recommend using SQLiteBrowser

The SQLiteWrapper story

The idea for SQLite Wrapper was purely dictated by the demand. We, at BuiltToRoam – company that I work at – are dealing with all types of universal application projects (Universal Apps for Windows 8.0-8.1 and Windows Phone 8.0-8.1 or UWP for Windows 10) that are required to use database(s). With every new application, we were basically re-using same code that was written for one of the previous apps. It was done in a really “savage” way, by copying and pasting core functionality and adjusting it accordingly to the needs of the app. Not good..something had to be done. The decision was made. We created a PCL (Portable Class Library) wrapper over SQLite.Net-PCL library that implements some basic functionality for Creating, Reading, Updating and Deleting (CRUD) operations on the database tables.

SQLiteWrapper came to life on a GitHub repository. From the beginning of it’s existence in the Open Source space I was tempted to create a NuGet package out of it. With NuGet package it would be much easier to distribute it and share it. On top of that, nothing would change in terms of GitHub repository, it would still be there so anyone could grab sources. Besides..I always wanted to have mine NuGet package, even though this one wouldn’t be strictly speaking mine. Even though it is a child that whole BuiltToRaom team gave birth to, I feel like at the moment I’m changing its dippers ;]. What’s more, creating this package could finally place myself on the map of .NET world!

I ended up reading some articles how to create a package, what should it consist in terms of information and description and a bit later..I present you SQLiteWrapperUWP-PCL! There’s still no information whatsoever about how to deal with it or how to use what’s inside of if. I will try to fill this gap by guiding you, reader, through the process of creating a really basic example of SQLiteWrapperUWP-PCL usage.

 

The SQLiteWrapperUWP-PCL example

 

The project

Let’s start with creating an empty solution in Visual Studio 2015 – I’m using Community edition.

Creating_Blank_VisualStudio_Solution

Next let’s add UWP project

Adding_UWP_Project

Next add a PCL (Portable Class Library)

Adding_PCL_Project

Adding_PCL_Project_Support_Selection

As you can see on the support selection screen (it appears after clicking OK on the dialog with Add New Project and choosing PCL), I’m selecting .NET Framework 4.6 and Windows Universal 10.0 (UWP).

After those steps you should end up, in your Solution Explorer, with something similar to this

SolutionExplorer_View

Having that done, we can grab NuGet packages and add it to the project. As SQLiteWrapperUWP-PCL depends on the SQLite.Net-PCL library we it will be installed along side SQLiteWrapperUWP-PCL

NuGet_Package_Manger_SQLiteWrapperUWP-PCL

New references should appear in both Core and UWP projects and in the NuGet Package Manger window green tick should appear next to libraries that were installed. Even after successful installation you still don’t seem to have SQLite.NET-PCL library referenced (in one or both of your projects) you should try installing it explicitly (by finding it in the NuGet Package Manager and installing it from there)

SQLiteWrapperUWP-PCL_Installed

You’re probably aware that to work with SQLite database one need an SQLite extension. In our case it’s going to be UWP extension. You can download one from Visual Studio, by going Tools –> Extensions and Updates and then selecting on the left side Online> Visual Studio Gallery and search for sqlite for universal

SQLite_UWP_Extension

After downloading SQLite for Universal App Platform you will be prompted with installer confirmation dialog

Confirm_SQLite_UWP_Extension_Installation

Remember to restart Visual Studio after installation has finished. Now you will be able to Add reference of this extension to your UWP project.

Adding_SQLite_Extension_To_UWP_Project

Then navigate – left side panel – to Universal Windows. SQLite for Universal App Platform should be listed in Extensions

Adding_SQLite_Extension_To_UWP_Project_Extension_Window

Click OK. Afterwards you should have your SQL extension visible under References in your UWP project

SQLite_Extension_Added

At some point you should add a reference to the Core (PCL) library in your UWP project. You can see that I already did that, look on the above screenshot, it sits just below the SQLite for Universal App Platform reference.

Last thing, that is not necessary but recommended is to install MvvmCross libraries. It can be done in the same way as we did with SQLiteWrapperUWP-PCL, which means that in the NuGet Package Manager find MvvmCross and install it in both projects. On the below screenshot you can see MvvmCross already installed

Adding_MvvmCross

Installation of MvvmCross framework will most likely create some folders and files in your project. To get familiar with MvvmCross and it’s structures, concepts and files I would recommend reading and/or watching some videos from the  N+1 days of MvvmCross blog posts.

In terms of preparing your project for this example that should be it, let’s proceed to the code part

The description, below, was for version of SQLiteWrapperUWP-PCL up to 1.0.0.3. For the new version you can find some information in my latest post on this subject

The code

Let’s start from the Core project and setting up the DatabaseService.

The base class – BaseDatabaseService – is the one that sits in our wrapper and is responsible for database management (e.g. creation, opening or closing). To create either BaseDatabaseService or in this case DatabaseService one will have to specify a constructor parameter of ISqlitePlatformProvider, I will explain that one in a moment. In the above code besides the constructor you can see an override of the CreateAndOpenDb method. It allows as to “plug in” between the creation of the database and returning connection to it. It’s done this way to make sure that before someone will start operating on the database (SQLiteConnection) they will have the proper entities – database tables – defined in it. In this case PersonEntity table is being created and afterwards dbConnection returned. Invoking dbConnection.CreateTable<PersonEntity>(); will map the model of our class to the database table. For more information about creating tables and mapping in general I’ll refer you to the SQLite.NET-PCL git project site, where you can find some examples.

PersonEntity is just an example of how you should structure your database entities. They should inherit from BaseEntity class so that you could use BaseRepository implementation – both of those classes are in the wrapper and about the second one I will talk in a moment. You should know that BaseEntity has a Id property which is decorated with [PrimaryKey] attribute and as you may suspect it will be mapped as a database table PrimaryKey.

Before explaining ISqlitePlatformProvider and BaseRepository concept I’ll quickly show you how I dealt with PersonService and Inserting and Retrieving data from database. Let’s start with very simple IPersonService interface that our service will implement

As simple as two methods, Insert and RetrieveAll. Implementation will sit in the PersonService.

Constructor takes SQLiteConnection which is the product of database service CreateAndOpen() method call. There’s also Insert and RetrieveAll implementation. Both use same pattern, which is BaseRepository<TEntity>. Repository part of the wrapper is the “thing” that you will deal with the most of the time. In above snippet of code I’m simply creating, for both methods, new BaseRepository<PersonEntity>, within using statement – because BaseRepository implements IDisplosable interface – which allows me to operate on my table (e.g. personRepo.Insert(person) or personRepo.Table.ToList()). Explore BaseRepository more to get familiar with functions that we exposed (e.g. Get or Delete).

That’s about it when it goes for Core, let’s move to the UWP project. Starting from mentioned earlier ISqlitePlatformProvider

That one is pretty easy. It’s purely about platform specific implementation of SQLite.Net-PLC library and how it will handle all the “low level” SQL database stuff. In this case our platform will be SQLitePlatformWinRT.

Last but not least is to put all this together and insert and retrieve some actual database entries.

I hope the comments and my walk through will let you understand what’s happening in this snipped of code. If you still have doubts you should definitely try it yourself! Start from checking out this SQLiteWrapperUWP-PCL example project that you just read about.

 

NOTE: For inspecting SQLite database file(s) I recommend using SQLiteBrowser