[data views] allow fields param to be passed to field caps request (#147666)

## Summary

Adds new optional `fields` argument to the data view fields for wildcard
api that allows the consumer to request only specific fields as opposed
to always getting all fields.

Co-authored-by: Steph Milovic <stephanie.milovic@elastic.co>
Co-authored-by: Julia Rechkunova <julia.rechkunova@elastic.co>

src/plugins/data_views/common/data_views/data_views.ts

@@ -497,12 +497,8 @@ export class DataViewsService {
   getFieldsForWildcard = async (options: GetFieldsOptions): Promise<FieldSpec[]> => {
     const metaFields = await this.config.get<string[]>(META_FIELDS);
     const { fields } = await this.apiClient.getFieldsForWildcard({
-      pattern: options.pattern,
+      ...options,
       metaFields,
-      type: options.type,
-      rollupIndex: options.rollupIndex,
-      allowNoIndex: options.allowNoIndex,
-      indexFilter: options.indexFilter,
     });
     return fields;
   };

src/plugins/data_views/common/types.ts

@@ -315,6 +315,7 @@ export interface GetFieldsOptions {
   allowNoIndex?: boolean;
   indexFilter?: QueryDslQueryContainer;
   includeUnmapped?: boolean;
+  fields?: string[];
 }
 
 /**

src/plugins/data_views/public/data_views/data_views_api_client.ts

@@ -49,8 +49,16 @@ export class DataViewsApiClient implements IDataViewsApiClient {
    * @param options options for fields request
    */
   getFieldsForWildcard(options: GetFieldsOptions) {
-    const { pattern, metaFields, type, rollupIndex, allowNoIndex, indexFilter, includeUnmapped } =
-      options;
+    const {
+      pattern,
+      metaFields,
+      type,
+      rollupIndex,
+      allowNoIndex,
+      indexFilter,
+      includeUnmapped,
+      fields,
+    } = options;
     return this._request<FieldsForWildcardResponse>(
       this._getUrl(['_fields_for_wildcard']),
       {
@@ -60,6 +68,7 @@ export class DataViewsApiClient implements IDataViewsApiClient {
         rollup_index: rollupIndex,
         allow_no_index: allowNoIndex,
         include_unmapped: includeUnmapped,
+        fields,
       },
       indexFilter ? JSON.stringify({ index_filter: indexFilter }) : undefined
     ).then((response) => {

src/plugins/data_views/server/fetcher/index_patterns_fetcher.ts

@@ -61,6 +61,7 @@ export class IndexPatternsFetcher {
     type?: string;
     rollupIndex?: string;
     indexFilter?: QueryDslQueryContainer;
+    fields?: string[];
   }): Promise<{ fields: FieldDescriptor[]; indices: string[] }> {
     const { pattern, metaFields = [], fieldCapsOptions, type, rollupIndex, indexFilter } = options;
     const patternList = Array.isArray(pattern) ? pattern : pattern.split(',');
@@ -81,6 +82,7 @@ export class IndexPatternsFetcher {
         include_unmapped: fieldCapsOptions?.includeUnmapped,
       },
       indexFilter,
+      fields: options.fields || ['*'],
     });
     if (type === 'rollup' && rollupIndex) {
       const rollupFields: FieldDescriptor[] = [];

src/plugins/data_views/server/fetcher/lib/es_api.test.js

@@ -161,7 +161,7 @@ describe('server/index_patterns/service/lib/es_api', () => {
       sinon.assert.calledOnce(fieldCaps);
 
       const passedOpts = fieldCaps.args[0][0];
-      expect(passedOpts).toHaveProperty('fields', '*');
+      expect(passedOpts).toHaveProperty('fields', ['*']);
       expect(passedOpts).toHaveProperty('ignore_unavailable', true);
       expect(passedOpts).toHaveProperty('allow_no_indices', false);
     });

src/plugins/data_views/server/fetcher/lib/es_api.ts

@@ -44,6 +44,7 @@ interface FieldCapsApiParams {
   indices: string[] | string;
   fieldCapsOptions?: { allow_no_indices: boolean; include_unmapped?: boolean };
   indexFilter?: QueryDslQueryContainer;
+  fields?: string[];
 }
 
 /**
@@ -67,12 +68,13 @@ export async function callFieldCapsApi(params: FieldCapsApiParams) {
       allow_no_indices: false,
       include_unmapped: false,
     },
+    fields = ['*'],
   } = params;
   try {
     return await callCluster.fieldCaps(
       {
         index: indices,
-        fields: '*',
+        fields,
         ignore_unavailable: true,
         index_filter: indexFilter,
         ...fieldCapsOptions,

src/plugins/data_views/server/fetcher/lib/field_capabilities/field_capabilities.test.js

@@ -36,6 +36,7 @@ describe('index_patterns/field_capabilities/field_capabilities', () => {
     indices: undefined,
     fieldCapsOptions: undefined,
     indexFilter: undefined,
+    fields: undefined,
     ...args,
   });
 

src/plugins/data_views/server/fetcher/lib/field_capabilities/field_capabilities.ts

@@ -21,6 +21,7 @@ interface FieldCapabilitiesParams {
   metaFields: string[];
   fieldCapsOptions?: { allow_no_indices: boolean; include_unmapped?: boolean };
   indexFilter?: QueryDslQueryContainer;
+  fields?: string[];
 }
 
 /**
@@ -34,12 +35,20 @@ interface FieldCapabilitiesParams {
  *  @return {Promise<{ fields: Array<FieldDescriptor>, indices: Array<string>>}>}
  */
 export async function getFieldCapabilities(params: FieldCapabilitiesParams) {
-  const { callCluster, indices = [], fieldCapsOptions, indexFilter, metaFields = [] } = params;
+  const {
+    callCluster,
+    indices = [],
+    fieldCapsOptions,
+    indexFilter,
+    metaFields = [],
+    fields,
+  } = params;
   const esFieldCaps = await callFieldCapsApi({
     callCluster,
     indices,
     fieldCapsOptions,
     indexFilter,
+    fields,
   });
   const fieldsFromFieldCapsByName = keyBy(readFieldCapsResponse(esFieldCaps.body), 'name');
 

src/plugins/data_views/server/index_patterns_api_client.ts

@@ -26,7 +26,8 @@ export class IndexPatternsApiServer implements IDataViewsApiClient {
     type,
     rollupIndex,
     allowNoIndex,
-    indexFilter: indexFilter,
+    indexFilter,
+    fields,
   }: GetFieldsOptions) {
     const indexPatterns = new IndexPatternsFetcher(this.esClient, allowNoIndex);
     return await indexPatterns
@@ -36,6 +37,7 @@ export class IndexPatternsApiServer implements IDataViewsApiClient {
         type,
         rollupIndex,
         indexFilter,
+        fields,
       })
       .catch((err) => {
         if (

src/plugins/data_views/server/routes/fields_for.ts

@@ -37,6 +37,7 @@ interface IQuery {
   rollup_index?: string;
   allow_no_index?: boolean;
   include_unmapped?: boolean;
+  fields?: string[];
 }
 
 const validate: RouteValidatorFullConfig<{}, IQuery, IBody> = {
@@ -49,6 +50,7 @@ const validate: RouteValidatorFullConfig<{}, IQuery, IBody> = {
     rollup_index: schema.maybe(schema.string()),
     allow_no_index: schema.maybe(schema.boolean()),
     include_unmapped: schema.maybe(schema.boolean()),
+    fields: schema.maybe(schema.arrayOf(schema.string())),
   }),
   // not available to get request
   body: schema.maybe(schema.object({ index_filter: schema.any() })),
@@ -86,6 +88,7 @@ const handler: RequestHandler<{}, IQuery, IBody> = async (context, request, resp
         includeUnmapped,
       },
       indexFilter,
+      fields: request.query.fields,
     });
 
     return response.ok({

test/api_integration/apis/data_views/fields_for_wildcard_route/response.js

@@ -90,6 +90,16 @@ export default function ({ getService }) {
         .then(ensureFieldsAreSorted);
     });
 
+    it('returns a single field as requested', async () => {
+      await supertest
+        .get('/api/index_patterns/_fields_for_wildcard')
+        .query({ pattern: 'basic_index', fields: JSON.stringify(['bar']) })
+        .expect(200, {
+          fields: [testFields[0]],
+          indices: ['basic_index'],
+        });
+    });
+
     it('always returns a field for all passed meta fields', async () => {
       await supertest
         .get('/api/index_patterns/_fields_for_wildcard')