Create README.md for the baskets module

docs/README.md

@@ -104,7 +104,7 @@ We can customize some features to use EShop in complex application scenarios.
   * Stores
 
 * Plugin modules
-  * Baskets
+  * [Baskets](https://github.com/EasyAbp/EShop/tree/dev/plugins/Baskets)
   * Coupons
   * Inventories
     * [DaprActors](https://github.com/EasyAbp/EShop/tree/dev/plugins/Inventories/DaprActors)

docs/plugins/baskets/README.md

@@ -0,0 +1,72 @@
+# EShop.Plugins.Baskets
+
+[![ABP version](https://img.shields.io/badge/dynamic/xml?style=flat-square&color=yellow&label=abp&query=%2F%2FProject%2FPropertyGroup%2FAbpVersion&url=https%3A%2F%2Fraw.githubusercontent.com%2FEasyAbp%2FEShop%2Fmaster%2FDirectory.Build.props)](https://abp.io)
+[![NuGet](https://img.shields.io/nuget/v/EasyAbp.EShop.Plugins.Baskets.Domain.Shared.svg?style=flat-square)](https://www.nuget.org/packages/EasyAbp.EShop.Plugins.Baskets.Domain.Shared)
+[![NuGet Download](https://img.shields.io/nuget/dt/EasyAbp.EShop.Plugins.Baskets.Domain.Shared.svg?style=flat-square)](https://www.nuget.org/packages/EasyAbp.EShop.Plugins.Baskets.Domain.Shared)
+[![Discord online](https://badgen.net/discord/online-members/S6QaezrCRq?label=Discord)](https://discord.gg/S6QaezrCRq)
+[![GitHub stars](https://img.shields.io/github/stars/EasyAbp/EShop?style=social)](https://www.github.com/EasyAbp/EShop)
+
+🛒 A baskets (cart) plugin for EShop. It supports both the server-side pattern and the client-side pattern.
+
+## Installation
+
+1. Install the following NuGet packages. ([see how](https://github.com/EasyAbp/EasyAbpGuide/blob/master/docs/How-To.md#add-nuget-packages))
+
+    * EasyAbp.EShop.Plugins.Baskets.Application
+    * EasyAbp.EShop.Plugins.Baskets.Application.Contracts
+    * EasyAbp.EShop.Plugins.Baskets.Domain
+    * EasyAbp.EShop.Plugins.Baskets.Domain.Shared
+    * EasyAbp.EShop.Plugins.Baskets.EntityFrameworkCore
+    * EasyAbp.EShop.Plugins.Baskets.HttpApi
+    * EasyAbp.EShop.Plugins.Baskets.HttpApi.Client
+    * (Optional) EasyAbp.EShop.Plugins.Baskets.MongoDB
+    * (Optional) EasyAbp.EShop.Plugins.Baskets.Web
+
+1. Add `DependsOn(typeof(EShopXxxModule))` attribute to configure the module dependencies. ([see how](https://github.com/EasyAbp/EasyAbpGuide/blob/master/docs/How-To.md#add-module-dependencies))
+
+1. Add `builder.ConfigureEShopPluginsBaskets();` to the `OnModelCreating()` method in **MyProjectMigrationsDbContext.cs**.
+
+1. Add EF Core migrations and update your database. See: [ABP document](https://docs.abp.io/en/abp/latest/Tutorials/Part-1?UI=MVC&DB=EF#add-database-migration).
+
+## Server-side Baskets Pattern
+
+The server-side basket is for identified(logon) users. It requests the basket [backend service APIs](https://github.com/EasyAbp/EShop/blob/dev/plugins/Baskets/src/EasyAbp.EShop.Plugins.Baskets.HttpApi/EasyAbp/EShop/Plugins/Baskets/BasketItems/BasketItemController.cs) are available.
+
+1. Before you create a basket item, use `/api/e-shop/orders/order/check-create` (POST) to check whether the current user is allowed to create an order with it.
+1. Use `/api/e-shop/plugins/baskets/basket-item` (POST) to create basket items on the server side. Extra properties are allowed.
+1. Use `/api/e-shop/plugins/baskets/basket-item` (GET) to get basket the item list. The returned "IsInvalid" property shows whether you can use the item to create an order.
+1. Use `/api/e-shop/plugins/baskets/basket-item/{id}` (PUT) or `/api/e-shop/plugins/baskets/basket-item/{id}` (DELETE) to change an item's quantity or remove an item.
+
+## Client-side Baskets Pattern
+
+You should store the basket items in the client(browser) cache as a collection of [IBasketItem](https://github.com/EasyAbp/EShop/blob/dev/plugins/Baskets/src/EasyAbp.EShop.Plugins.Baskets.Domain.Shared/EasyAbp/EShop/Plugins/Baskets/BasketItems/IBasketItem.cs). The client-side doesn't depend on the baskets module backend service APIs.
+
+### With Backend
+
+If you install the backend, it provides APIs to help refresh your client-side basket items.
+
+1. Before you create a basket item, use `/api/e-shop/orders/order/check-create` (POST) to check whether the current user is allowed to create an order with it.
+1. Use `/api/e-shop/plugins/baskets/basket-item/generate-client-side-data` (POST) to refresh your client-side basket items anytime.
+
+### Without Backend
+
+If you don't install the backend, you can still create and store the basket items locally, but the client-side basket items will not validate and never update.
+
+## How To Determine a Basket Pattern
+
+The server-side baskets pattern will take effect if all the following conditions are met:
+1. The baskets module backend has been installed and is available.
+1. The `EasyAbp.EShop.Plugins.Baskets.EnableServerSideBaskets` setting value is "True".
+1. The current user has the `EasyAbp.EShop.Plugins.Baskets.BasketItem` permission.
+
+## What if Anonymous Users Add Basket Items and Then Log In?
+
+The client(browser) should try to add the existing items to the server-side and remove them from the client-side. You can implement it by referring to the [index.js](https://github.com/EasyAbp/EShop/blob/dev/plugins/Baskets/src/EasyAbp.EShop.Plugins.Baskets.Web/Pages/EShop/Plugins/Baskets/BasketItems/BasketItem/index.js).
+
+## Use Basket Items To Create an Order
+
+We don't provide a built-in way to convert basket items to an order creation DTO.
+
+Create an order manually by the front end, and remember to map the basket item's extra properties to the order creation DTO since some special product may need them.
+
+After creating the order, the front end should clear the unused basket items.

plugins/Baskets/README.md

@@ -0,0 +1 @@
+../../docs/plugins/baskets/README.md