日韩一级黄色大片,特级黄一级播放,日韩av在线中文字幕

本文介紹了用于條件保存的 DynamoDBMapper的處理方法，對(duì)大家解決問(wèn)題具有一定的參考價(jià)值，需要的朋友們下面隨著小編來(lái)一起學(xué)習(xí)吧！

問(wèn)題描述

我正在使用 DynamoDBMapper，并且希望有條件地保存當(dāng)且僅當(dāng) hashkey 和 range 鍵組合不存在時(shí).我知道有一些方法可以使用 UUID 來(lái)減少發(fā)生沖突的可能性，但我想通過(guò)使用條件保存來(lái)保護(hù)自己.

I'm using DynamoDBMapper and would like to conditionally save if and only if the hashkey and range key combination does not exist. I know there are ways to use UUIDs to reduce the possibility of a collision but I would like to protect myself by using conditional saves.

我遇到了這篇文章使用 DynamoDBSaveExpression 但是我無(wú)法指定條件是hashkey AND rangekey"不能存在.API 指定withConditionalOperator 方法，但我在課堂上看不到這個(gè).我也在使用來(lái)自 here 的最新 aws java sdk.

I came across this article that uses DynamoDBSaveExpression however I'm not able to specify that the condition is "hashkey AND rangekey" cannot exist. The API specifies a withConditionalOperator method but I'm not able to see this in my class. I am using the latest aws java sdk also from here.

關(guān)于如何有條件地保存的任何建議?或者我可能做錯(cuò)了什么?

Any suggestions on how to conditionally save? Or what I may be doing incorrectly?

推薦答案

DynamoDBSaveExpression saveExpression = new DynamoDBSaveExpression();
Map<String, ExpectedAttributeValue> expectedAttributes = 
    ImmutableMap.<String, ExpectedAttributeValue>builder()
        .put("hashKey", new ExpectedAttributeValue(false))
        .put("rangeKey", new ExpectedAttributeValue(false))
        .build();
saveExpression.setExpected(expectedAttributes);
saveExpression.setConditionalOperator(ConditionalOperator.AND);
try {
    dynamoDBMapper.save(objectToSave, saveExpression);
} catch (ConditionalCheckFailedException e) {
    //Handle conditional check
}

這使用 public ExpectedAttributeValue(Boolean exists) 構(gòu)造函數(shù)，它只是在內(nèi)部調(diào)用 setExists.

This uses the public ExpectedAttributeValue(Boolean exists) constructor, which just internally calls setExists.

這篇關(guān)于用于條件保存的 DynamoDBMapper的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！

【網(wǎng)站聲明】本站部分內(nèi)容來(lái)源于互聯(lián)網(wǎng),旨在幫助大家更快的解決問(wèn)題，如果有圖片或者內(nèi)容侵犯了您的權(quán)益，請(qǐng)聯(lián)系我們刪除處理，感謝您的支持！

久久久久久久av_日韩在线中文_看一级毛片视频_日本精品二区_成人深夜福利视频_武道仙尊动漫在线观看

用于條件保存的 DynamoDBMapper

問(wèn)題描述

推薦答案

相關(guān)文檔推薦