有限制的 AWS dynamoDb 分页

Question

我正在尝试对在 dynamoDb 中创建的 table 中的条目进行分页无论如何检查是否超过 table 项。

例如，如果我调用从 table 中获取项目，我会收到以下错误


PANIC: runtime error: invalid memory address or nil pointer dereference
goroutine 51 [running]:
github.com/urfave/negroni.(*Recovery).ServeHTTP.func1(0xdfae028, 0xc000186028, 0xc0002162d0, 0xc000154200)
    /Users/hammadali/go/pkg/mod/github.com/urfave/negroni@v1.0.0/recovery.go:159 +0xcb
panic(0x498ea20, 0x51f4410)
    /usr/local/Cellar/go/1.14.5/libexec/src/runtime/panic.go:969 +0x166
github.com/prohousing-as/ph-supplier-service/application.(*SupplierService).GetAllSuppliers(0xc0002cc300, 0xc00002a270, 0x24, 0xbb8, 0xc0004403e0, 0x0, 0x0)
    /Users/hammadali/source/ph-supplier-service/application/supplier_service.go:41 +0x330
github.com/prohousing-as/ph-supplier-service/ui.(*SupplierController).GetAllSupplier(0xc000526ed0, 0xdfae028, 0xc000186028, 0xc0003be300)
    /Users/hammadali/source/ph-supplier-service/ui/supplier_controller.go:40 +0x139
net/http.HandlerFunc.ServeHTTP(0xc000527170, 0xdfae028, 0xc000186028, 0xc0003be300)
    /usr/local/Cellar/go/1.14.5/libexec/src/net/http/server.go:2041 +0x44
github.com/gorilla/mux.(*Router).ServeHTTP(0xc0002e40c0, 0xdfae028, 0xc000186028, 0xc0003be100)
    /Users/hammadali/go/pkg/mod/github.com/gorilla/mux@v1.7.4/mux.go:210 +0xe2

获取所有项目的函数

// fetches the items from dynamoDb and stores it in res
res, err := s.SupplierRepo.GetAllSupplier(uuid, limit)
    if err != nil {
        fmt.Println("from application: ", err)
        return nil, err
    }
    item := &domain.SupplierTableItems{}
    all := &domain.AllSupplierItems{}
    // Looping over the result and appending it on the list
    for _, i := range res.Items {
        err = dynamodbattribute.UnmarshalMap(i, item)
        all.Collection = append(all.Collection, *item)
        if err != nil {
            fmt.Println(err)
        }
    }
    // storing lastEvaluatedKey for pagination
    all.LastEvaluatedKey = *res.LastEvaluatedKey["uuid"].S
    return all, nil

有没有办法检查为获取项目所做的调用是否超过了 table 个条目，并且只提供剩余的条目数。

Answer 1

您的错误与 DynamoDB 的分页没有太大关系，您只是想访问 /Users/hammadali/source/ph-supplier-service/application/supplier_service.go:41

附近某处不存在的内容

以其他方式回答您的问题：是的，DynamoDB 会在分页完成时告诉您。 From the docs:

If the result contains a LastEvaluatedKey element and it's non-null, proceed to step 2.

If there is not a LastEvaluatedKey in the result, there are no more items to be retrieved.

有限制的 AWS dynamoDb 分页

AWS dynamoDb pagination with limit

go

amazon-web-services

amazon-dynamodb