Handling Selection Logic

We’re almost done with this set of changes. The last thing to add for now is the ability for the user to click on either of the lists and select the item that was clicked on. Right now, we’re just defaulting to using the first item in an array as the “current” item for display in the Details sections.

We’ll start with the Pilots list. We don’t have a reducer for anything pilot-related yet, so we’ll create one. Going along with the idea of “normalization”, all we need to store is the ID of the currently selected pilot. We’ll actually get a bit fancy with the reducer logic, and handle de-selecting the current item entirely if the user clicks on it again:

Commit 593e570: Add logic for tracking the currently selected pilot

features/pilots/pilotsReducer.js

import {createReducer} from "common/utils/reducerUtils";

import {PILOT_SELECT} from "./pilotsConstants";

const initialState = {
    currentPilot : null
};

export function selectPilot(state, payload) {
    const prevSelectedPilot = state.currentPilot;
    const newSelectedPilot = payload.currentPilot;

    const isSamePilot = prevSelectedPilot === newSelectedPilot;
    
    return {
        // Deselect entirely if it's a second click on the same pilot,
        // otherwise go ahead and select the one that was clicked
        currentPilot : isSamePilot ? null : newSelectedPilot,
    };
}

export default createReducer(initialState, {
    [PILOT_SELECT] : selectPilot,
});

That gives us some data handling, but we need to hook that up to the UI. We need to pull the currentPilot ID value into <Pilots>, and use that in a couple places. We should pass the actual entry for the current pilot into <PilotDetails>, and it would also be nice to highlight the row for that pilot in the list. We also need to call the selectPilot action creator with the ID of the pilot whose row was just clicked on. Let’s look at the relevant changes:

Commit 9062899: Implement selection handling for pilots

features/pilots/Pilots.jsx

// Omit initial imports

+import {selectPilot} from "../pilotsActions";
+import {selectCurrentPilot} from "../pilotsSelectors";

const mapState = (state) => {}
    // Omit pilot objects lookup

+   const currentPilot = selectCurrentPilot(state);

    // Now that we have an array of all pilot objects, return it as a prop
-   return {pilots};
+   return {pilots, currentPilot};
}


+// Make an object full of action creators that can be passed to connect
+// and bound up, instead of writing a separate mapDispatch function
+const actions = {
+    selectPilot,
+};

export class Pilots extends Component {
    render() {
-       const {pilots = []} = this.props;
+       const {pilots = [], selectPilot, currentPilot} = this.props;

-       const currentPilot = pilots[0] || {};
+       const currentPilotEntry = pilots.find(pilot => pilot.id === currentPilot) || {}

        // Omit irrelevant layout component rendering for space
        return (
            <Segment>
-               <PilotsList pilots={pilots} />
+               <PilotsList
+                   pilots={pilots}
+                   onPilotClicked={selectPilot}
+                   currentPilot={currentPilot}
+               />
-               <PilotDetails pilot={currentPilot} />
+               <PilotDetails pilot={currentPilotEntry} />
            </Segment>
        );
    }
}

-export default connect(mapState)(Pilots);
+export default connect(mapState, actions)(Pilots);

features/pilots/PilotsList/PilotsList.jsx

export default class PilotsList extends Component {
    render() {
-       const {pilots} = this.props;
+       const {pilots, onPilotClicked, currentPilot} = this.props;

        const pilotRows = pilots.map(pilot => (
-           <PilotsListRow pilot={pilot} key={pilot.name}/>
+           <PilotsListRow
+               pilot={pilot}
+               key={pilot.name}
+               onPilotClicked={onPilotClicked}
+               selected={pilot.id === currentPilot}
+           />
        ));

        // Omit layout rendering for space
    }

features/pilots/PilotsList/PilotsListRow.jsx

+import _ from "lodash";

-const PilotsListRow = ({pilot={}}) => {
+const PilotsListRow = ({pilot={}, onPilotClicked=_.noop, selected}) => {
    const {
+        id = null,
        // Omit other fields
    } = pilot;

    return (
-       <Table.Row>
+       <Table.Row onClick={() => onPilotClicked(id)} active={selected}>

And voila! If we click on an entry in the pilots list, we should now see that row highlighted, and the entry also shown in the <PilotDetails> form: