This library provides a means to use the Angular Material mat-autocomplete component, in cases where the options to be populated must arrive asynchronously (for example, because they come from a server). The resulting behavior is more like a server-side "search select", in that it is intended to allow entry of only developer approved values.
Demo running at:
To use this in a project
There are two ways to consume the code here. You can see examples of them in the various tabs of the demo.
- Use the provided obs-autocomplete component, as shown in "simple", "Long slow", "real API".
- Write a custom component using only the base class provided in this package;
your component will provide all the visuals, but typically doesn't need to
provide any code at all. For an example of this, look in the source code,
demo-5-multicolumnand the corresponding multicolumn demo tab.
For better or worse, various aspects of HTML, CSS, Angular, and other tools conspire to frequently require option 2. This is the only way to provide full flexibility in the appearance of the component, to match your application's needs.
Regardless of which layout approach you choose, at run time you must provide a DataSource, which is similar conceptually to the DataSource concept used by a mat-table; that interface defines (and application code must provide) methods:
- Method which searches for a values, and provides corresponding display text.
- Method which takes a search query fragment and provides a list of match candidates.
- Optionally, a match method that can widen the definition of a matching entry - for example, make it a user can type an entry that varies from a list entry only in upper/lowercase.
Study the example code in the various
demo-N-* for more about these methods.
It shows several ways to provide such a data source.
How it works, and why
To behave correctly, this component must accommodate the asynchronous nature of the lookup data. This turns out to be rather complex.
We have found this problem comes up regularly on our projects, and have finally created a generic solution, reusable. It is not ultimately reusable though, because it is bound to Angular Material, which we use on many projects.
This repository/project contains both the component itself, and screens that demonstrate its use.
Also an example of how to publish a component
In addition to being a useful component, we have been using this repository as an example of how to publish a Angular component to NPM. You can see these patterns in use here, and borrow them for other components:
- Use ng-packagr. Outsource much of the complexity in bundling to that brilliant package.
- Start with a Angular CLI project.
- Add a module inside, for the components to be packaged.
- Make the overall application provide a demo, test environment, etc. for the components.