New function: metadata from multiple datastreams

Retrieves metadata from an array of Datastream URL strings

public/js/appChart.js

@@ -167,7 +167,7 @@ const axiosGetRequest = function (urlObservations, urlParamObj) {
  * @param {String} urlDatastream A URL that fetches a Datastream from an STA instance
  * @returns {Promise} A promise that contains a metadata object for a Datastream when fulfilled
  */
-const getDatastreamMetadata = async function (urlDatastream) {
+const getMetadataFromSingleDatastream = async function (urlDatastream) {
   try {
     // Extract properties of interest
     const {
@@ -180,6 +180,29 @@ const getDatastreamMetadata = async function (urlDatastream) {
   }
 };
 
+/**
+ * Retrieve metadata from multiple datastreams
+ * @param {Array} datastreamsUrlArr An array that contains N Datastream URL strings
+ * @returns {Promise} A promise that contains an array of N Datastream metadata objects when fulfilled
+ */
+const getMetadataFromMultipleDatastreams = async function (datastreamsUrlArr) {
+  try {
+    // Array to store our final result
+    const datastreamMetadataArr = [];
+
+    // Use for/of loop - we need to maintain the order of execution of the async operations
+    for (const datastreamUrl of datastreamsUrlArr) {
+      // Metadata from a single Datastream
+      const datastreamMetadata = await getDatastreamMetadata(datastreamUrl);
+      datastreamMetadataArr.push(datastreamMetadata);
+    }
+
+    return datastreamMetadataArr;
+  } catch (err) {
+    console.error(err);
+  }
+};
+
 /**
  * Format the response containing a Datastream's metadata from Sensorthings API
  * @param {Object} datastreamMetadata An object containing a Datastream's metadata
@@ -505,20 +528,21 @@ const getCombinedObservationsFromAllNextLinks = function (
 const getMetadataPlusObservationsForChart = async function (
   metadataPlusObsPromiseArray
 ) {
-  // Array to store our final result
-  const combinedResolvedPromises = [];
+  try {
+    // Array to store our final result
+    const combinedResolvedPromises = [];
 
-  // Use for/of loop - we need to maintain the order of execution of the async operations
-  for (const promise of metadataPlusObsPromiseArray) {
-    try {
+    // Use for/of loop - we need to maintain the order of execution of the async operations
+    for (const promise of metadataPlusObsPromiseArray) {
       // Resolved value of a single promise
       const resolvedPromise = await promise;
       combinedResolvedPromises.push(resolvedPromise);
-    } catch (err) {
-      console.error(err);
     }
+
+    return combinedResolvedPromises;
+  } catch (err) {
+    console.error(err);
   }
-  return combinedResolvedPromises;
 };
 
 /**
@@ -530,20 +554,21 @@ const getMetadataPlusObservationsForChart = async function (
 const getObservationsFromMultipleDatastreams = async function (
   observationPromiseArray
 ) {
-  // Array to store our final result
-  const observationsAllDatastreamsArr = [];
+  try {
+    // Array to store our final result
+    const observationsAllDatastreamsArr = [];
 
-  // Use for/of loop - we need to maintain the order of execution of the async operations
-  for (const observationPromise of observationPromiseArray) {
-    try {
+    // Use for/of loop - we need to maintain the order of execution of the async operations
+    for (const observationPromise of observationPromiseArray) {
       // Observations from a single Datastream
       const observations = await observationPromise;
       observationsAllDatastreamsArr.push(observations);
-    } catch (err) {
-      console.error(err);
     }
+
+    return observationsAllDatastreamsArr;
+  } catch (err) {
+    console.error(err);
   }
-  return observationsAllDatastreamsArr;
 };
 
 // Building + phenomenon + sampling rate
@@ -748,7 +773,7 @@ const drawScatterPlotHC = function (
   );
 
   // Create promises
-  const promiseDatastreamMetadataSeries1 = getDatastreamMetadata(
+  const promiseDatastreamMetadataSeries1 = getMetadataFromSingleDatastream(
     URL_DATASTREAM_SERIES_1
   );
   const promiseCombinedObservationsSeries1 =
@@ -756,7 +781,7 @@ const drawScatterPlotHC = function (
       axiosGetRequest(URL_OBSERVATIONS_SERIES_1, QUERY_PARAMS_COMBINED)
     );
 
-  const promiseDatastreamMetadataSeries2 = getDatastreamMetadata(
+  const promiseDatastreamMetadataSeries2 = getMetadataFromSingleDatastream(
     URL_DATASTREAM_SERIES_2
   );
   const promiseCombinedObservationsSeries2 =
@@ -799,7 +824,7 @@ export {
   getObservationsUrl,
   createTemporalFilterString,
   axiosGetRequest,
-  getDatastreamMetadata,
+  getMetadataFromSingleDatastream,
   formatDatastreamMetadataForChart,
   formatSTAResponseForHeatMap,
   drawHeatMapHC,

public/js/dropDownList.js

@@ -7,7 +7,7 @@ import {
   getDatastreamUrl,
   getObservationsUrl,
   axiosGetRequest,
-  getDatastreamMetadata,
+  getMetadataFromSingleDatastream,
   formatDatastreamMetadataForChart,
   formatSTAResponseForHeatMap,
   drawHeatMapHC,
@@ -289,7 +289,8 @@ const selectChartTypeFromDropDown = async function () {
     const URL_OBSERVATIONS = getObservationsUrl(BASE_URL, selectedDatastream);
 
     // Create promises
-    const promiseDatastreamMetadata = getDatastreamMetadata(URL_DATASTREAM);
+    const promiseDatastreamMetadata =
+      getMetadataFromSingleDatastream(URL_DATASTREAM);
     const promiseCombinedObservations = getCombinedObservationsFromAllNextLinks(
       axiosGetRequest(URL_OBSERVATIONS, QUERY_PARAMS_COMBINED)
     );