要使用AppSync订阅过滤器,您需要在AppSync模式中为每个订阅定义一个过滤器规则。以下是一个包含代码示例的解决方法:
type Subscription {
newPost(filter: PostFilter): Post
}
input PostFilter {
authorId: ID
category: String
}
Type: AWS::AppSync::Resolver
Properties:
ApiId: !Ref MyApi
TypeName: Subscription
FieldName: newPost
DataSourceName: !Ref MyDataSource
RequestMappingTemplate: |
{
"version": "2017-02-28",
"payload": {
"authorId": $util.defaultIfNull($ctx.args.filter.authorId, ""),
"category": $util.defaultIfNull($ctx.args.filter.category, "")
}
}
ResponseMappingTemplate: "$util.toJson($ctx.result)"
import { API, graphqlOperation } from 'aws-amplify';
const subscription = API.graphql(graphqlOperation(`
subscription NewPost($filter: PostFilter) {
newPost(filter: $filter) {
id
title
content
}
}
`, { filter: { authorId: '123', category: 'news' } }));
subscription.subscribe({
next: (data) => {
console.log('New post:', data);
},
error: (error) => {
console.error('Error:', error);
},
complete: () => {
console.log('Subscription complete');
},
});
在上面的代码示例中,我们使用了GraphQL操作graphqlOperation
来定义订阅,并传递了过滤器参数filter
来订阅特定作者ID和类别的新文章。您可以根据需要调整过滤器参数值。
这就是使用AppSync订阅过滤器的解决方法,希望对您有所帮助!