Data middleware and resource

[tomdye]

Type: bug / feature

The following has been addressed in the PR:

• There is a related issue
• All code has been formatted with prettier as per the readme code style guidelines
• Unit or Functional tests are included in the PR

Description:

Adds a data middleware capable of making widgets data aware and able to deal with a resource.

• When using the middleware, resource will be added to the widget's properties. This can be used to pass a resource to be interacted with.
• Provides createDataMiddleware function which takes a generic to determine the type of data the widget requires, this adds a transform function to the widget properties which uses the generic to ensure the correct data type is supplied.

Data middleware API interface:

• getOrRead(options: ResourceOptions): any;
• getTotal(options: ResourceOptions): number | undefined;
• isLoading(options: ResourceOptions): boolean;
• isFailed(options: ResourceOptions): boolean;
• isLoading(options: ResourceOptions): boolean;
• isFailed(options: ResourceOptions): boolean;
• isLoading(options: ResourceOptions): boolean;
• isFailed(options: ResourceOptions): boolean;
• setOptions(newOptions: ResourceOptions): void;
• getOptions(): ResourceOptions;
• readonly resource: ResourceWrapper;
• shared(): ResourceWrapper;

ResourceOptions are made up of:

• pageNumber?: number
• pageSize?: number
• query?: string

When a widget using the middleware is destroyed, the middleware will disconnect from the resource.

The Resource will need to provide the following API

• getOrRead(options: ResourceOptions: any
• getTotal(options: ResourceOptions): number | undefined
• unsubscribe(invalidator: () => void): void
• subscribe(type: SubscriptionType, options: ResourceOptions, invalidator: () => void): void;
• isLoading(options: ResourceOptions): boolean;
• isFailed(options: ResourceOptions): boolean;

Both API

Will work in future with resources.

Resolves #660

Codesandbox of it in use with dummy resource: https://codesandbox.io/s/hardcore-swartz-kezpc

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[matt-gadd]

do we use this abbreviation elsewhere? sb?

[tomdye]

believe so

[tomdye]

everywhere

[agubler]

For APIs that do not provide a total the current implementation can be problematic, which means they will become less useful for using externally controlled/managed APIs. For example without a real total, returning a partial last page or an empty array (for APIs where there are no results) causes an infinite loop calling the user resource. It would be good is we could make the total option in some way to support this use case.

Additionally it would be beneficial if the data api could be used without providing pagination details, for example if a user wants to return a single resource.

Here is an implementation of the HNPWA using data/resources that demonstrates these two scenarios https://github.com/agubler/dojo-resource-hnpwa

The resources are defined in App.tsx https://github.com/agubler/dojo-resource-hnpwa/blob/master/src/App.tsx

matt is unavailable