Showing results

Lens result format

When your application has queried a backend and receives results from sites, it has to pass these results to Lens so it can display them. Lens expects results of type LensResult, for example:

{
    "stratifiers": {
        "gender": {
            "female": 31,
            "male": 43
        },
        "diagnosis": {
            "C34.0": 26,
            "C34.2": 28,
            "C34.8": 25
        }
    },
    "totals": {
        "patients": 74,
        "samples": 312
    }
}

The totals field contains the total number of patients, samples, etc. The stratifiers field contains stratum counts (e.g. male, female) for each stratifier (e.g. gender). The specific stratifiers depend on the application. When you add a chart to your application you specify which stratifier it should display.

Focus can return the Lens result format directly. If you are quering a FHIR server you can convert a FHIR measure report to the Lens result format using the measureReportToLensResult function.

Passing results to Lens

You pass results to Lens using the setSiteResult function. Before you pass a result you may call markSiteClaimed to indicate that the site is available and will deliver results soon. If a site that was claimed fails you can use removeFailedSite to hide the site from the result summary and result table and remove the site out of the resultstore. This examples shows how you would pass results from Focus to Lens.

querySpot(query, abortController.signal, (result: SpotResult) => {
    const site = result.from.split(".")[1];
    if (result.status === "claimed") {
        markSiteClaimed(site);
    } else if (result.status === "succeeded") {
        const siteResult = JSON.parse(atob(result.body));
        setSiteResult(site, siteResult);
    } else {
        removeFailedSite(site);
        console.error(
            `Site ${site} failed with status ${result.status}:`,
            result.body,
        );
    }
});

Handling Empty Query Results

Sometimes a query may succeed but return no data, with totals of 0 and empty stratifiers. In these cases, it’s recommended to check for an empty result and inform the user.

Include this function:

export function isLensResultEmpty(result: LensResult): boolean {
    // Check for non-empty stratifiers
    for (const stratifier of Object.values(result.stratifiers)) {
        if (Object.keys(stratifier).length > 0) return false;
    }

    // Check for non-zero totals
    for (const value of Object.values(result.totals)) {
        if (value !== 0) return false;
    }

    return true;
}

And check in your result function:

if (isLensResultEmpty(result)) {
    showToast("No results found for your query", "info");
}

Components

Lens provides components to render results.

• Result Table
• Result Summary
• Chart