DexieNET

DexieCloudNET is a .NET wrapper for dexie.js minimalist wrapper for IndexedDB see https://dexie.org with cloud support see https://dexie.org/cloud/ .

'DexieNET' used with permission of David Fahlander

News

Preview released for DexieCloud
Please register with DexieCloud and test the ToDoSample. The configuration script can be found here configure-app.ps1 (Windows) or here configure-app.sh (Nix - jq required).
Published a new helper library RxBlazorLight

Basic

DexieNET aims to be a feature complete .NET wrapper for Dexie.js the famous Javascript IndexedDB wrapper from David Fahlander including support for cloud sync.

I consists of two parts, a source generator converting a C# record, class, struct to a DB store and a set of wrappers around the well known Dexie.js API constructs such as Table, WhereClause, Collection, ...

It's designed to work within a Blazor Webassembly application with minimal effort.

Hello World

create a Blazor WebAssembly
Add the DexieNET Nuget
Add the HelloWorld Component and update the index

Program.cs

using DexieNET;
using YourNamspace.Pages;
....

builder.Services.AddDexieNET<FriendsDB>();

HelloWorld.razor

@page "/helloWorld"
@using DexieNET.Component
@inherits DexieNET<FriendsDB>

Friends:
@if (_friends is null)
{
    <p>Loading...</p>
}
else if (_friends.Count() == 0)
{
    <p>No items...</p>
}
else
{
    <ul style="list-style: square inside;">
        @foreach (var friend in _friends)
        {
            <li>
                Name: @friend.Name, Age: @friend.Age
            </li>
        }
    </ul>
}

<hr />

Logs:
@if (_logs is null)
{
    <p>Loading...</p>
}
else if (_logs.Count() == 0)
{
    <p>No items...</p>
}
else
{
    <ul style="list-style: square inside;">
        @foreach (var logEntry in _logs)
        {
            <li>
                Message: @logEntry.Message, TimeStamp: @logEntry.TimeStamp.ToLongTimeString();
            </li>
        }
    </ul>
}

<hr />

<div style="display: flex; column-gap: 50px">
    <button class="btn btn-primary" style="flex: 0 1 auto" @onclick="PopulateDatabase">
        PopulateDatabase
    </button>

    <button class="btn btn-secondary" style="flex: 0 1 auto" @onclick="GoodTransaction">
        GoodTransaction
    </button>

    <button class="btn btn-secondary" style="flex: 0 1 auto" @onclick="FailedTransaction">
        FailedTransaction
    </button>

    <button class="btn btn-secondary" style="flex: 0 1 auto" @onclick="ClearDatabase">
        ClearDatabase
    </button>
</div>

HelloWorld.razor.cs

using DexieNET;
using System.ComponentModel.DataAnnotations;
using System.Runtime.InteropServices;
using System.Xml.Linq;

namespace DexieNETHelloWorld.Pages
{
    public interface IFriendsDB : IDBStore { };

    public partial record Friend
    (
        [property: Index] string Name,
        [property: Index] int Age
    ) : IFriendsDB;

    public partial record LogEntry
    (
        [property: Index] string? Message,
        [property: Index] DateTime TimeStamp
    ) : IFriendsDB;

    public partial class HelloWorld
    {
        private IEnumerable<Friend>? _friends;
        private IEnumerable<LogEntry>? _logs;

        protected override async Task OnInitializedAsync()
        {
            await base.OnInitializedAsync();
            await Dexie.Version(1).Stores();
            await FillTables();
        }

        private async Task FillTables()
        {
            _friends = await Dexie.Friends().ToArray();
            _logs = await Dexie.LogEntries().OrderBy(l => l.TimeStamp).Reverse().ToArray();
            await InvokeAsync(StateHasChanged);
        }

        private async Task LogMessage(string? message)
        {
            await Dexie.Transaction(async _ =>
            {
                await Dexie.LogEntries().Add(new LogEntry(message, DateTime.Now));
            }, TAType.TopLevel);
        }
        private async Task ClearDatabase()
        {
            await Dexie.Friends().Clear();
            await Dexie.LogEntries().Clear();

            await FillTables();
        }

        private async Task PopulateDatabase()
        {
            await LogMessage("PopulateDatabase");

            Random rand = new();
            await Dexie.Friends().Add(new Friend("Jane Doe", rand.Next(1, 99)));
            await Dexie.Friends().Add(new Friend("John Doe", rand.Next(1, 99)));

            await FillTables();
        }

        private async Task GoodTransaction()
        {
            await LogMessage("GoodTransaction");

            await Dexie.Transaction(async ta =>
            {
                Random rand = new();
                var key = await Dexie.Friends().Add(new Friend("Luke", rand.Next(1, 99)));
                var friend = await Dexie.Friends().Get(key);

                if (friend?.Name == "Luke" || ta.Collecting)
                // ta.Collecting, this means the first pass of the transaction, in which the table names are collected
                // if a second table is hidden behind a conditional statement, it must also be visited in the first pass
                {
                    await Dexie.Friends().Add(new Friend("John", rand.Next(1, 99)));
                    await Dexie.LogEntries().Add(new LogEntry("TA executed", DateTime.Now));
                }
            });

            await FillTables();
        }

        private async Task FailedTransaction()
        {
            await LogMessage("ProvokeFail");

            try
            {
                await Dexie.Transaction(async ta =>
                {
                    await Dexie.Friends().Clear();
                    var key = await Dexie.Friends().Add(new Friend("Test", 33));
                    var friend = await Dexie.Friends().Get(key);

                    if (friend?.Name == "Test" || ta.Collecting)
                    {
                        await LogMessage("TA will fail");
                    }
                    await Dexie.Friends().Add(friend); // this will fail
                });
            }
            catch (Exception ex)
            {
                var firstDot = ex.Message.IndexOf('.');
                var message = firstDot <= 0 ? ex.Message : ex.Message[..firstDot];
                await LogMessage($"TA failed: {message}");
            }

            await FillTables();
        }
    }
}

Advanced

Naming

the Source Generator will create the following classes from an IDBStore derived class, struct, record:

PIndentifier -> Plural of Identifier provided by Humanizer.Core (English only), be aware the plural form might not be always obvious e.g. Person -> People
service: PIndentifierDB
table: PIndentifier

// Record
public partial record Friend
(
    [property: Index] string Name,
    [property: Index] int Age
) : IDBStore;

......
// Service
builder.Services.AddDexieNET<FriendsDB>();
......
[Inject]
public IDexieNETService<FriendsDB>? DB { get; set; }

......
// Table
var table = await DB.Friends();

You can have multiple stores in one database

 [DBName("TestDB")] // optional -> default name = interface name without leading 'I' -> PersonsDB
 public interface IPersonsDB : IDBStore
 {
 }

 // Records
 [CompoundIndex("FirstName", "LastName")]
 public partial record Person
 (
     [property: Index] string FirstName,
     [property: Index] string LastName,
     Guid? AddressKey
 ) : IPersonsDB;

 [CompoundIndex("City", "Street")]
 [CompoundIndex("Zip", "Street")]
 public partial record Address
 (
     [property: Index] string Street,
     [property: Index] string Housenumber,
     [property: Index] string City,
     [property: Index] string ZIP,
     [property: Index] string Country

 ) : IPersonsDB;

 ......
 // Service
 using DexieNET;
 .......
 builder.Services.AddDexieNET<TestDB>();
 
 // Component
 [Inject]
 public IDexieNETService<TestDB>? TestDB { get; set; }

 ......
 // Table
 var persons = await TestDB.Persons();
 var addresses = await TestDB.Addresses();

Transactions

transactions capture the table names in two passes
if a second table is hidden behind a conditional statement, it must also be visited in the first pass
nested transactions contain all required table names
top level transactions must use TAType.TopLevel, the root transaction is implictly a top level transaction
parallel transactions are composed by a root transaction with TAType.TopLevel and top level child transactions

Samples

The tests from TestCases will cover all possible DexieNET Api calls. Those calls are as close as possible modelled after the original Dexie.js API.

b-straub / DexieNET