Fix plotting series when the first data point is empty.

- Add `graphql` to the dependencies, to help interacting with the schema.
- Get the schema in parallel with the first data query and remember it.
- Use it to find the numeric fields under the data paths, instead of inspecting the first data point.

Author: Tony Hignett

dist/module.js

@@ -25,7 +25,7 @@
       { "name": "GitHub Security Advisories", "path": "img/github_security_advisories.png"}
     ],
     "version": "1.3.0",
-    "updated": "2021-03-16"
+    "updated": "2021-05-25"
   },
 
   "dependencies": {

dist/module.js.map

@@ -18,6 +18,7 @@
     "moment": "*"
   },
   "dependencies": {
-    "@types/lodash": "^4.14.144"
+    "@types/lodash": "^4.14.144",
+    "graphql": "^15.5.0"
   }
 }

dist/plugin.json

@@ -19,28 +19,31 @@ import {
   MyVariableQuery,
   MultiValueVariable,
   TextValuePair,
+  RequestFactory,
 } from './types';
 import { dateTime, MutableDataFrame, FieldType, DataFrame } from '@grafana/data';
 import { getTemplateSrv } from '@grafana/runtime';
-import _ from 'lodash';
 import { isEqual } from 'lodash';
 import { flatten, isRFC3339_ISO6801 } from './util';
+import { GraphQLObjectType, isObjectType } from 'graphql';
+import { Schema } from './schema';
 
 const supportedVariableTypes = ['constant', 'custom', 'query', 'textbox'];
 
-export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
-  basicAuth: string | undefined;
-  withCredentials: boolean | undefined;
-  url: string | undefined;
-
-  constructor(instanceSettings: DataSourceInstanceSettings<MyDataSourceOptions>, private backendSrv: any) {
-    super(instanceSettings);
-    this.basicAuth = instanceSettings.basicAuth;
-    this.withCredentials = instanceSettings.withCredentials;
-    this.url = instanceSettings.url;
+class _RequestFactory implements RequestFactory {
+  constructor(
+    private basicAuth: string | undefined,
+    private withCredentials: boolean | undefined,
+    private url: string,
+    private backendSrv: any
+  ) {
+    this.basicAuth = basicAuth;
+    this.withCredentials = withCredentials;
+    this.url = url;
+    this.backendSrv = backendSrv;
   }
 
-  private request(data: string) {
+  request(data: string): Promise<any> {
     const options: any = {
       url: this.url,
       method: 'POST',
@@ -60,9 +63,26 @@ export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
 
     return this.backendSrv.datasourceRequest(options);
   }
+}
+
+export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
+  private schema: Schema;
+  private requestFactory: RequestFactory;
+
+  constructor(instanceSettings: DataSourceInstanceSettings<MyDataSourceOptions>, backendSrv: any) {
+    super(instanceSettings);
+    this.requestFactory = new _RequestFactory(
+      instanceSettings.basicAuth,
+      instanceSettings.withCredentials,
+      instanceSettings.url as string,
+      backendSrv
+    );
+    this.schema = new Schema(this.requestFactory);
+  }
 
   private postQuery(query: Partial<MyQuery>, payload: string) {
-    return this.request(payload)
+    return this.requestFactory
+      .request(payload)
       .then((results: any) => {
         return { query, results };
       })
@@ -138,12 +158,15 @@ export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
   }
 
   async query(options: DataQueryRequest<MyQuery>): Promise<DataQueryResponse> {
-    return Promise.all(
-      options.targets.map((target) => {
-        return this.createQuery(defaults(target, defaultQuery), options.range, options.scopedVars);
-      })
-    ).then((results: any) => {
+    let promises: Array<Promise<any>> = options.targets.map((target) => {
+      return this.createQuery(defaults(target, defaultQuery), options.range, options.scopedVars);
+    });
+    promises.push(this.schema.getQuery());
+
+    return Promise.all(promises).then((results: any[]) => {
       const dataFrameArray: DataFrame[] = [];
+      let queryType: GraphQLObjectType = results.pop();
+
       for (let res of results) {
         const dataPathArray: string[] = DataSource.getDataPathArray(res.query.dataPath);
         const { timePath, timeFormat, groupBy, aliasBy } = res.query;
@@ -157,6 +180,10 @@ export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
         }
         for (const dataPath of dataPathArray) {
           const docs: any[] = DataSource.getDocs(res.results.data, dataPath);
+          let dataType = Schema.getTypeOfDescendant(queryType, dataPath);
+          if (!isObjectType(dataType)) {
+            throw `Data path ${dataPath} has type ${dataType.name}, expected object type`;
+          }
 
           const dataFrameMap = new Map<string, MutableDataFrame>();
           for (const doc of docs) {
@@ -180,9 +207,13 @@ export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
                 let t: FieldType = FieldType.string;
                 if (fieldName === timePath || isRFC3339_ISO6801(String(doc[fieldName]))) {
                   t = FieldType.time;
-                } else if (_.isNumber(doc[fieldName])) {
-                  t = FieldType.number;
+                } else {
+                  let fieldType = Schema.getTypeOfDescendant(dataType, fieldName);
+                  if (Schema.isNumericType(fieldType)) {
+                    t = FieldType.number;
+                  }
                 }
+
                 let title;
                 if (identifiers.length !== 0) {
                   // if we have any identifiers

package.json

@@ -0,0 +1,46 @@
+import { GraphQLFloat, GraphQLInt, GraphQLObjectType, GraphQLString } from 'graphql';
+import { Schema } from './schema';
+
+test('getTypeOfDescendant', () => {
+  const childType = new GraphQLObjectType({
+    name: 'child-type',
+    fields: {
+      grandchild1: { type: GraphQLInt },
+      grandchild2: { type: GraphQLFloat },
+    },
+  });
+  const parentType = new GraphQLObjectType({
+    name: 'parent-type',
+    fields: {
+      child1: { type: GraphQLString },
+      child2: {
+        type: childType,
+      },
+    },
+  });
+
+  expect(Schema.getTypeOfDescendant(parentType, 'child1')).toBe(GraphQLString);
+  expect(Schema.getTypeOfDescendant(parentType, 'child2')).toBe(childType);
+  expect(Schema.getTypeOfDescendant(parentType, 'child2.grandchild1')).toBe(GraphQLInt);
+  expect(Schema.getTypeOfDescendant(parentType, 'child2.grandchild2')).toBe(GraphQLFloat);
+  expect(Schema.getTypeOfDescendant(childType, 'grandchild1')).toBe(GraphQLInt);
+});
+
+describe('isNumericType', () => {
+  test('object', () => {
+    const type = new GraphQLObjectType({ name: 'Address', fields: { street: { type: GraphQLString } } });
+    expect(Schema.isNumericType(type)).not.toBeTruthy();
+  });
+
+  test('string', () => {
+    expect(Schema.isNumericType(GraphQLString)).not.toBeTruthy();
+  });
+
+  test('int', () => {
+    expect(Schema.isNumericType(GraphQLInt)).toBeTruthy();
+  });
+
+  test('float', () => {
+    expect(Schema.isNumericType(GraphQLFloat)).toBeTruthy();
+  });
+});

src/DataSource.ts

@@ -0,0 +1,55 @@
+import {
+  buildClientSchema,
+  getIntrospectionQuery,
+  getNamedType,
+  GraphQLNamedType,
+  GraphQLObjectType,
+  isObjectType,
+  isScalarType,
+  printSchema,
+} from 'graphql';
+import { RequestFactory } from './types';
+
+export class Schema {
+  private query: Promise<GraphQLObjectType> | undefined;
+
+  constructor(private requestFactory: RequestFactory) {
+    this.requestFactory = requestFactory;
+  }
+
+  getQuery(): Promise<GraphQLObjectType> {
+    if (!this.query) {
+      this.query = this.requestFactory.request(getIntrospectionQuery()).then((results: any) => {
+        let schema = buildClientSchema(results.data.data);
+        let queryType = schema.getQueryType();
+        if (!queryType) {
+          throw `No query type in schema: ${printSchema(schema)}`;
+        }
+        return queryType;
+      });
+    }
+    // @ts-ignore (it's defined now)
+    return this.query;
+  }
+
+  static getTypeOfDescendant(nodeType: GraphQLObjectType, path: string): GraphQLNamedType {
+    let descendantType = nodeType;
+    let pathComponents = path.split('.');
+    for (let i = 0; i < pathComponents.length; i++) {
+      let type = getNamedType(descendantType.getFields()[pathComponents[i]].type);
+      if (i === pathComponents.length - 1) {
+        return type;
+      } else {
+        if (!isObjectType(type)) {
+          throw `Found type ${type.name} for component ${pathComponents[i]} of ${path}, expected object type`;
+        }
+        descendantType = type as GraphQLObjectType;
+      }
+    }
+    return descendantType;
+  }
+
+  static isNumericType(fieldType: GraphQLNamedType): boolean {
+    return isScalarType(fieldType) && (fieldType.name === 'Int' || fieldType.name === 'Float');
+  }
+}

src/schema.test.ts

@@ -56,3 +56,7 @@ export interface MultiValueVariable extends VariableModel {
   current: TextValuePair;
   options: TextValuePair[];
 }
+
+export interface RequestFactory {
+  request(data: string): Promise<any>;
+}

src/schema.ts

@@ -1795,10 +1795,10 @@
   resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.6.tgz#f4c7ec43e81b319a9815115031709f26987891f0"
   integrity sha512-3c+yGKvVP5Y9TYBEibGNR+kLtijnj7mYrXRg+WpFb2X9xm04g/DXYkfg4hmzJQosc9snFNUPkbYIhu+KAm6jJw==
 
-"@types/lodash@^4.14.144":
-  version "4.14.167"
-  resolved "https://registry.yarnpkg.com/@types/lodash/-/lodash-4.14.167.tgz#ce7d78553e3c886d4ea643c37ec7edc20f16765e"
-  integrity sha512-w7tQPjARrvdeBkX/Rwg95S592JwxqOjmms3zWQ0XZgSyxSLdzWaYH3vErBhdVS/lRBX7F8aBYcYJYTr5TMGOzw==
+"@types/lodash@^4.14.170":
+  version "4.14.170"
+  resolved "https://registry.yarnpkg.com/@types/lodash/-/lodash-4.14.170.tgz#0d67711d4bf7f4ca5147e9091b847479b87925d6"
+  integrity sha512-bpcvu/MKHHeYX+qeEN8GE7DIravODWdACVA1ctevD8CN24RhPZIKMn9ntfAsrvLfSX3cR5RrBKAbYm9bGs0A+Q==
 
 "@types/mime@*":
   version "2.0.3"
@@ -5786,6 +5786,11 @@ graceful-fs@^4.1.11, graceful-fs@^4.1.15, graceful-fs@^4.1.2, graceful-fs@^4.1.6
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.2.4.tgz#2256bde14d3632958c465ebc96dc467ca07a29fb"
   integrity sha512-WjKPNJF79dtJAVniUlGGWHYGz2jWxT6VhN/4m1NdkbZ2nOsEF+cI1Edgql5zCRhs/VsQYRvrXctxktVXZUkixw==
 
+graphql@^15.5.0:
+  version "15.5.0"
+  resolved "https://registry.yarnpkg.com/graphql/-/graphql-15.5.0.tgz#39d19494dbe69d1ea719915b578bf920344a69d5"
+  integrity sha512-OmaM7y0kaK31NKG31q4YbD2beNYa6jBBKtMFT6gLYJljHLJr42IqJ8KX08u3Li/0ifzTU5HjmoOOrwa5BRLeDA==
+
 growly@^1.3.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/growly/-/growly-1.3.0.tgz#f10748cbe76af964b7c96c93c6bcc28af120c081"