Add Filtering

readme.md

@@ -49,7 +49,7 @@ Congratulations, the server is running. 🚀
 The most important parts are implemented and working properly but we have room for improvements.
 
 - [ ] Ordering
-- [ ] Filtering
+- [X] Filtering
 - [ ] Custom arguments example
 - [ ] Error handling
 - [ ] DataLoader
@@ -205,3 +205,28 @@ Backward with cursor
   }
 }
 ```
+
+With Filter
+
+```graphql
+{
+  products(last: 2, name: "Something") {
+    edges {
+      node {
+        id
+        name
+        description
+        createdAt
+        updatedAt
+      }
+      cursor
+    }
+    pageInfo {
+      startCursor
+      endCursor
+      hasPreviousPage
+      hasNextPage
+    }
+  }
+}
+```

src/modules/product/product.resolver.ts

@@ -13,8 +13,14 @@ export class ProductResolver {
   private service!: ProductService
 
   @Query(() => ProductConnection)
-  async products(@Args() args: ConnectionArgs): Promise<ProductConnection> {
-    return this.service.paginate(args)
+  async products(
+    @Args() args: ConnectionArgs,
+    @Arg('name', () => String, { nullable: true }) product_name: string
+  ): Promise<ProductConnection> {
+    return this.service.paginate(
+      args,
+      product_name ? { name: product_name } : undefined
+    )
   }
 
   @Mutation(() => AddProductPayload)

src/modules/product/product.service.ts

@@ -1,5 +1,5 @@
 import { Service } from 'typedi'
-import { Repository } from 'typeorm'
+import { FindConditions, Repository } from 'typeorm'
 import { InjectRepository } from 'typeorm-typedi-extensions'
 
 import { ProductEntity } from './product.entity'
@@ -13,8 +13,11 @@ export class ProductService {
   @InjectRepository(ProductEntity)
   private readonly repository!: Repository<ProductEntity>
 
-  async paginate(args: ConnectionArguments): Promise<ProductConnection> {
-    return connectionFromRepository(args, this.repository)
+  async paginate(
+    args: ConnectionArguments,
+    filter?: FindConditions<ProductEntity>
+  ): Promise<ProductConnection> {
+    return connectionFromRepository(args, this.repository, filter)
   }
 
   async findById(id: string): Promise<ProductEntity | undefined> {

src/relay/connection.factory.ts

@@ -4,15 +4,18 @@ import {
   getOffsetWithDefault,
   offsetToCursor
 } from 'graphql-relay'
-import { Repository } from 'typeorm'
+import { FindConditions, Repository } from 'typeorm'
 
 export async function connectionFromRepository<T>(
   args: ConnectionArguments,
-  repository: Repository<T>
+  repository: Repository<T>,
+  filterArg?: FindConditions<T>
 ): Promise<Connection<T>> {
   const { before, after, first, last } = args
 
-  const total = await repository.count()
+  const where = filterArg ? { where: filterArg } : undefined
+
+  const total = await repository.count(where)
 
   // offsets
   const beforeOffset = getOffsetWithDefault(before, total)
@@ -34,7 +37,7 @@ export async function connectionFromRepository<T>(
   const take = Math.max(endOffset - startOffset, 1) // sql limit
 
   // records
-  const entities = await repository.find({ skip, take })
+  const entities = await repository.find({ skip, take, where })
 
   const edges = entities.map((entity, index) => ({
     cursor: offsetToCursor(startOffset + index),