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

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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: Querymutation: 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