aws(学习笔记第四十八课) appsync-graphql-dynamodb

aws(学习笔记第四十八课) appsync-graphql-dynamodb

• 使用graphql来方便操作dynamodb
• 理解graphql中的graphql api，schema，resolver

学习内容：

• graphql
• graphql api
• schema
• resolver

---

1. 代码连接和修改

1.1 代码链接

代码链接（appsync-graphql-dynamodb）

1.2 代码修改

1.2.1 加上必要的depencies

各个resolver创建的时候，都是需要data_source的，所以需要事前将resolver的depencies加上data source。

        get_one_resolver.add_depends_on(data_source)
        get_all_resolver.add_depends_on(data_source)
        save_resolver.add_depends_on(data_source)
        delete_resolver.add_depends_on(data_source)

1.2.2 加上必要的outputs

        CfnOutput(
            self, "AppSyncApiUrl",
            value=items_graphql_api.attr_graph_ql_url,
            description="AppSync GraphQL API URL"
        )
        CfnOutput(
            self, "AppSyncApiKey",
            value=items_api_key.attr_api_key,  # 假设已定义 items_api_key = CfnApiKey(...)
            description="AppSync API Key"
        )

2. 整体架构

• 定义一个graphql api
• 为了安全访问，定义一个api key
• 定义一个api schema
  • 两个查询api，all和get one
  • 定义两个更新api，delete和save
• 定义了一个dynamo table，用来存储数据
• 对schema定义了四个resolver
  • all resovler
  • get one resolver
  • save resolver
  • delete resolver

3. 代码详细

3.1 定义api以及api key

 table_name = 'items'

        items_graphql_api = CfnGraphQLApi(
            self, 'ItemsApi',
            name='items-api',
            authentication_type='API_KEY'
        )

        items_api_key = CfnApiKey(
            self, 'ItemsApiKey',
            api_id=items_graphql_api.attr_api_id
        )

3.2 定义api的schema

 api_schema = CfnGraphQLSchema(
            self, 'ItemsSchema',
            api_id=items_graphql_api.attr_api_id,
            definition=f"""\
                type {table_name} {{
                    {table_name}Id: ID!
                    name: String
                }}
                type Paginated{table_name} {{
                    items: [{table_name}!]!
                    nextToken: String
                }}
                type Query {{
                    all(limit: Int, nextToken: String): Paginated{table_name}!
                    getOne({table_name}Id: ID!): {table_name}
                }}
                type Mutation {{
                    save(name: String!): {table_name}
                    delete({table_name}Id: ID!): {table_name}
                }}
                type Schema {{
                    query: Query
                    mutation: Mutation
                }}"""
        )

3.3 定义dynamoDB table

 items_table = Table(
            self, 'ItemsTable',
            table_name=table_name,
            partition_key=Attribute(
                name=f'{table_name}Id',
                type=AttributeType.STRING
            ),
            billing_mode=BillingMode.PAY_PER_REQUEST,
            stream=StreamViewType.NEW_IMAGE,

            # The default removal policy is RETAIN, which means that cdk
            # destroy will not attempt to delete the new table, and it will
            # remain in your account until manually deleted. By setting the
            # policy to DESTROY, cdk destroy will delete the table (even if it
            # has data in it)
            removal_policy=RemovalPolicy.DESTROY # NOT recommended for production code
        )

3.4 定义dynamoDB访问的role，以及data source

这里data source，可以看出是将graphql api和dynamoDB的table进行关联。

      items_table_role = Role(
            self, 'ItemsDynamoDBRole',
            assumed_by=ServicePrincipal('appsync.amazonaws.com')
        )

        items_table_role.add_managed_policy(
            ManagedPolicy.from_aws_managed_policy_name(
                'AmazonDynamoDBFullAccess'
            )
        )

        data_source = CfnDataSource(
            self, 'ItemsDataSource',
            api_id=items_graphql_api.attr_api_id,
            name='ItemsDynamoDataSource',
            type='AMAZON_DYNAMODB',
            dynamo_db_config=CfnDataSource.DynamoDBConfigProperty(
                table_name=items_table.table_name,
                aws_region=self.region
            ),
            service_role_arn=items_table_role.role_arn
        )

3.5 定义四个api resolver

3.5.1 get one resolver

        get_one_resolver = CfnResolver(
            self, 'GetOneQueryResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Query',
            field_name='getOne',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "GetItem",
                "key": {{
                "{table_name}Id": $util.dynamodb.toDynamoDBJson($ctx.args.{table_name}Id)
                }}
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )
        get_one_resolver.add_depends_on(api_schema)
        get_one_resolver.add_depends_on(data_source)

3.5.2 all resolver

get_all_resolver = CfnResolver(
            self, 'GetAllQueryResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Query',
            field_name='all',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "Scan",
                "limit": $util.defaultIfNull($ctx.args.limit, 20),
                "nextToken": $util.toJson($util.defaultIfNullOrEmpty($ctx.args.nextToken, null))
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )

        get_all_resolver.add_depends_on(api_schema)
        get_all_resolver.add_depends_on(data_source)

3.5.3 save resolver

        save_resolver = CfnResolver(
            self, 'SaveMutationResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Mutation',
            field_name='save',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "PutItem",
                "key": {{
                    "{table_name}Id": {{ "S": "$util.autoId()" }}
                }},
                "attributeValues": {{
                    "name": $util.dynamodb.toDynamoDBJson($ctx.args.name)
                }}
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )
        save_resolver.add_depends_on(api_schema)
        save_resolver.add_depends_on(data_source)

3.5.4 delete resolver

        delete_resolver = CfnResolver(
            self, 'DeleteMutationResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Mutation',
            field_name='delete',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "DeleteItem",
                "key": {{
                "{table_name}Id": $util.dynamodb.toDynamoDBJson($ctx.args.{table_name}Id)
                }}
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )

        delete_resolver.add_depends_on(api_schema)
        delete_resolver.add_depends_on(data_source)

3.5.5 增加outputs

为了能够得到graphql api的endpoint url，还有访问api key，这里进行outputs的输出

      CfnOutput(
            self, "AppSyncApiUrl",
            value=items_graphql_api.attr_graph_ql_url,
            description="AppSync GraphQL API URL"
        )
        CfnOutput(
            self, "AppSyncApiKey",
            value=items_api_key.attr_api_key,  # 假设已定义 items_api_key = CfnApiKey(...)
            description="AppSync API Key"
        )

4. 执行stack

4.1 执行stack

python -m venv ./venv
source .venv/Scripts/activate
pip install -r requirements.txt
cdk --require-approval never deploy

4.2 使用postman进行api调用，更新和查询dynamoDB table

4.2.1 生成GraphQL Request

4.2.2 使用save进行数据做成

在authorization的tab上进行api key的设定。

指定完毕，可以看到生成的数据中，已经生成了itemsID。

4.2.3 使用all进行数据查询

5. 及时cleanup