From f5ad2e0ff79fbf003e2363cfcd8630a1f9693a3c Mon Sep 17 00:00:00 2001
From: Danny Mikhaylov <danny.mhlv@gmail.com>
Date: Tue, 8 Nov 2022 05:18:17 +0300
Subject: [PATCH] Changed 'match' query to 'multi-match'. Allows to search for
 both 'content' and 'title' of the paper

---
 .../domain/dtos/elastic/es-multimatch.dto.ts  | 68 +++++++++++++++++++
 src/core/services/common/search.service.ts    | 11 ++-
 2 files changed, 72 insertions(+), 7 deletions(-)
 create mode 100644 src/core/domain/dtos/elastic/es-multimatch.dto.ts

diff --git a/src/core/domain/dtos/elastic/es-multimatch.dto.ts b/src/core/domain/dtos/elastic/es-multimatch.dto.ts
new file mode 100644
index 0000000..6617fea
--- /dev/null
+++ b/src/core/domain/dtos/elastic/es-multimatch.dto.ts
@@ -0,0 +1,68 @@
+import { ApiExtraModels, ApiProperty, ApiPropertyOptional } from "@nestjs/swagger";
+import { IsArray, IsDefined, IsInt, IsObject, IsOptional } from "class-validator";
+import { EsPit } from "../../interfaces/elastic/es-pit.interface";
+import { EsQuery } from "../../interfaces/elastic/es-query.interface"
+
+/**
+ * List of allowed properties in this DTO
+ */
+ const allowedProperties = ['query'];
+
+ /**
+  * Elasticsearch multi-match query DTO
+  */
+ @ApiExtraModels()
+ export class EsMultimatchQueryDto {
+    /**
+     * Offset from the start of the list of hits
+     */
+    @IsOptional()
+    @IsInt()
+    @ApiPropertyOptional({
+        description: 'Offset from the start of the list of hits',
+        example: 5,
+    })
+    public from?: number;
+
+    /**
+     * Maximum number of elements returned by Elasticsearch
+     */
+    @IsOptional()
+    @IsInt()
+    @ApiPropertyOptional({
+        description: 'Maximum number of elements returned by Elasticsearch',
+        example: 30
+    })
+    public size?: number;
+    
+    /**
+     * The search query object passed to Elasticsearch
+     */
+    @IsDefined()
+    @IsObject()
+    @ApiProperty({
+        description: 'Search query object passed to Elasticsearch',
+        example: {
+            multi_match: {
+                query: 'Maths',
+                fields: [
+                    'title',
+                    'content'
+                ]
+            }
+        },
+    })
+    private readonly query: Object;
+
+    /**
+     * Constructs a multi-match
+     */
+    constructor(query: string = '', fields: Array<string> = ['content']) {
+        this.query = {
+            multi_match: {
+                query: query,
+                fields: fields
+            }
+        }
+    }
+ }
\ No newline at end of file
diff --git a/src/core/services/common/search.service.ts b/src/core/services/common/search.service.ts
index b037ab5..7e5a47c 100644
--- a/src/core/services/common/search.service.ts
+++ b/src/core/services/common/search.service.ts
@@ -1,6 +1,7 @@
 import { HttpService } from "@nestjs/axios";
 import { GatewayTimeoutException, ImATeapotException, Injectable, NotFoundException } from "@nestjs/common";
 import { map, take } from "rxjs";
+import { EsMultimatchQueryDto } from "src/core/domain/dtos/elastic/es-multimatch.dto";
 import { EsResponseDto, SearchQueryDto} from "../../domain/dtos";
 import { EsQueryDto } from "../../domain/dtos/elastic/es-query.dto";
 
@@ -69,13 +70,9 @@ export class SearchService {
      */
     async findByContext(query: SearchQueryDto): Promise<EsResponseDto> {
         // Contruct a body for querying Elasticsearch
-        const es_query: EsQueryDto = new EsQueryDto();
-        es_query.query = {
-            query_string: {
-                query: query.query,
-                default_field: 'content',
-            }
-        };
+        const es_query: EsMultimatchQueryDto = new EsMultimatchQueryDto(query.query, [
+            'title', 'content'
+        ]);
         es_query.from = query.offset;
         es_query.size = query.limit;