better task validation

src/services/exporter.ts

@@ -33,13 +33,14 @@ export class Exporter {
       this._task.id = uuidv4();
       this._task.progress = _.cloneDeep(DEFAULT_PROGRESS);
 
+      this._validateQueries(task.queries);
+      this._validateDatasourceUrl(datasourceUrl);
+
       const targets = task.queries.map((query: DashboardQuery) => new Target(
         query.panel,
         query.datasource,
       ));
 
-      this._validateTargets(datasourceUrl, targets);
-
       await this._updateProgress();
 
       const queryConfigs = targets.map(
@@ -127,15 +128,22 @@ export class Exporter {
     }
   }
 
-  private _validateTargets(datasourceUrl: string, targets: Target[]) {
-    if(!targets || !Array.isArray(targets)) {
-      throw new Error('Incorrect targets format');
+  private _validateQueries(queries: DashboardQuery[]) {
+    if(!queries || !Array.isArray(queries)) {
+      throw new Error('`queries` field is required and should be an array');
     }
 
-    if(targets.length > 1) {
-      throw new Error(`Multiple queries are not supported yet`);
+    for(const query of queries) {
+      if(!_.isEmpty(query.datasource)) {
+        throw new Error('all queries should have a `datasource` field');
+      }
+      if(!_.isEmpty(query.panel.targets)) {
+        throw new Error('all queries should have a `panel` field with non-empty `targets` field');
+      }
     }
+  }
 
+  private _validateDatasourceUrl(datasourceUrl: string) {
     const host = new URL(datasourceUrl).origin;
     const apiKey = apiKeys[host];