move error message rewrite to source of errors

before "explore" and the graph panel did show the original (non
rewritten) error message.

currently we have two problems with that implementation:
1. the error message is translated, so this only works in english
   instances of checkmk
2. we duplicated the code between rest and web api.

for 1. we plan to introduce a feature in the REST-API (but this will
only solve the problem in `src/backend/rest.ts` not for the webapi!), we
probably have to live with the code duplication.

Author: BenediktSeidl

src/backend/rest.ts

@@ -10,13 +10,19 @@ import {
   TimeRange,
   dateTime,
 } from '@grafana/data';
-import { BackendSrvRequest, FetchResponse, getBackendSrv } from '@grafana/runtime';
+import { BackendSrvRequest, FetchError, FetchResponse, getBackendSrv } from '@grafana/runtime';
 import { Aggregation, GraphType } from 'RequestSpec';
 
 import { CmkQuery } from '../types';
 import { createCmkContext, updateQuery } from '../utils';
 import { Backend, DatasourceOptions } from './types';
 
+type RestApiError = {
+  detail: string;
+  status: number;
+  title: string;
+};
+
 type RestApiGraphResponse = {
   time_range: {
     start: string;
@@ -118,7 +124,8 @@ export default class RestApiBackend implements Backend {
     try {
       result = await getBackendSrv().fetch<T>(request).toPromise();
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    } catch (error: any) {
+    } catch (e) {
+      const error = e as FetchError<RestApiError>;
       // grafana error handling is only showing status code and status message,
       // but we may have a more detailed error message
       if (error.status === 404) {
@@ -128,6 +135,12 @@ export default class RestApiBackend implements Backend {
       }
 
       if (error.data && error.data.title && error.data.detail) {
+        // TODO: error message is translated, see CMK-12886
+        if (error.data.detail === 'Sorry, you cannot create combined graphs for more than 100 objects') {
+          throw new Error(
+            'Result size limit reached. Please add more filters to reduce the number of elements in the result.'
+          );
+        }
         throw new Error(`${error.data.title} ${error.data.detail}`);
       }
       throw error;

src/backend/web.ts

@@ -1,5 +1,5 @@
 import { DataQueryRequest, DataQueryResponse, FieldType, MutableDataFrame } from '@grafana/data';
-import { BackendSrvRequest, FetchResponse, getBackendSrv } from '@grafana/runtime';
+import { BackendSrvRequest, FetchError, FetchResponse, getBackendSrv } from '@grafana/runtime';
 import { defaults, get, isUndefined, zip } from 'lodash';
 
 import { CmkQuery, defaultQuery } from '../types';
@@ -77,11 +77,13 @@ export default class WebApiBackend implements Backend {
       data: buildRequestBody(data),
     });
   }
+
   async cmkRequest<T>(request: BackendSrvRequest): Promise<FetchResponse<WebApiResponse<T>>> {
     const result = await getBackendSrv()
       .fetch<WebApiResponse<T>>(request)
       .toPromise()
-      .catch((error) => {
+      .catch((e) => {
+        const error = e as FetchError<unknown>;
         if (error.cancelled) {
           throw new Error(
             `API request was cancelled. This has either happened because no 'Access-Control-Allow-Origin' header is present, or because of a ssl protocol error. Make sure you are running at least Checkmk version 2.0.`
@@ -101,10 +103,17 @@ export default class WebApiBackend implements Backend {
     if (typeof result.data === 'string') {
       throw new Error(`${result.data}`);
     } else if (result.data.result_code !== 0) {
+      // error handling in web api: error is not transported via http-status codes :-/
       let message = `${result.data}`;
       if (result.data.result !== undefined) {
         message = `${result.data.result}`;
       }
+      // TODO: error message is translated, see CMK-12886
+      if (message === 'Sorry, you cannot create combined graphs for more than 100 objects') {
+        throw new Error(
+          'Result size limit reached. Please add more filters to reduce the number of elements in the result.'
+        );
+      }
       throw new Error(message);
     } else {
       return result;

src/ui/components.tsx

@@ -96,13 +96,7 @@ export const CheckMkGenericAsyncSelect = function <Value extends string | (strin
       } catch (e) {
         const error = e as Error;
         if (error && error.message) {
-          if (error.message === 'Sorry, you cannot create combined graphs for more than 100 objects') {
-            setAutocompleteError(
-              'Result size limit reached. Please add more filters to reduce the number of elements in the result.'
-            );
-          } else {
-            setAutocompleteError(error.message);
-          }
+          setAutocompleteError(error.message);
         }
         throw error;
       }