add getAssetMetadata() function

src/aquarius/Aquarius.ts

@@ -146,6 +146,37 @@ export class Aquarius {
     return status
   }
 
+  /**
+   * Search over the DDOs using a query.
+   * @param {string} did DID of the asset
+   * @param {AbortSignal} signal abort signal
+   * @return {Promise<QueryResult>}
+   */
+  public async getAssetMetadata(did: string, signal?: AbortSignal): Promise<any> {
+    const path = this.aquariusURL + '/api/aquarius/assets/metadata/' + did
+
+    try {
+      const response = await fetch(path, {
+        method: 'GET',
+        headers: {
+          'Content-Type': 'application/json'
+        },
+        signal: signal
+      })
+
+      if (response.ok) {
+        return response.json()
+      } else {
+        throw new Error(
+          'getAssetMetadata failed: ' + response.status + response.statusText
+        )
+      }
+    } catch (error) {
+      LoggerInstance.error('Error getting metadata: ', error)
+      throw new Error('Error getting metadata: ', error)
+    }
+  }
+
   /**
    * Search over the DDOs using a query.
    * @param  {SearchQuery} query Query to filter the DDOs.
@@ -168,8 +199,7 @@ export class Aquarius {
       if (response.ok) {
         return response.json()
       } else {
-        LoggerInstance.error('querySearch failed: ', response.status, response.statusText)
-        return null
+        throw new Error('querySearch failed: ' + response.status + response.statusText)
       }
     } catch (error) {
       LoggerInstance.error('Error querying metadata: ', error)