来自 Nodejs 的 Base 64 使用 oracledb 查询 blob 数据返回空缓冲区

Question

blob contents - PHN2ZyB3aWR0aD0iMjQiIGhlaWdodD0iMjQiIHZpZXdCb3g9IjAgMCAyNCAyNCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIiBmb2N1c2FibGU9ImZhbHNlIj48cGF0aCBkPSJNMTIgMWM2LjA3NCAwIDEwLjk5OSA0LjkyNSAxMC45OTkgMTEgMCA2LjA3NC00LjkyNSAxMC45OTktMTEgMTAuOTk5LTYuMDc0IDAtMTAuOTk5LTQuOTI1LTEwLjk5OS0xMUMxIDUuOTI1IDUuOTI1IDEgMTIgMXptMCAxOC4xNzNhNy4xNzQgNy4xNzQgMCAxMC0uMDAxLTE0LjM0NyA3LjE3NCA3LjE3NCAwIDAwMCAxNC4zNDd6bTAtMy42NTNhMy41MiAzLjUyIDAgMTEwLTcuMDQgMy41MiAzLjUyIDAgMDEwIDcuMDR6IiBmaWxsLXJ1bGU9ImV2ZW5vZGQiPjwvcGF0aD48L3N2Zz4K

    const chainNumber = req.params.chainNumber;

    try {
        connection.execute(
        `select logo
        from chain_logos
        where chain_id = :1`,
        [chainNumber], {
            outFormat: oracledb.ARRAYBUFFER
        },
        async function(err, result) {
            if (err) {
                console.error(err.message);
                return;
            }
            connection.close();

            const data = result.rows.map(row => ({
                logo: Buffer.from(row[0]).toString('base64'),
                logo2: Buffer.from(row[0], 'base64'),
                logo3: row[0]
            }))
            return res.send({ data });
        });
    } catch (err) {
        console.log('Error: ', err);
        return res.send(`error returning chain logo`);
    }

即使有 blob 数据，我也只看到从代码返回的空缓冲区： {"data":[{"logo":"==","logo2":{"type":"Buffer","data":[0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]} ,"logo3":{"_readableState":{"objectMode":false,"highWaterMark":16384,"buffer":{"head":null,"tail":null,"length":0},"length" :0,"pipes":[],"flowing":null,"end":false,"endEmitted":false,"reading":false,"sync":true,"needReadable":false,"emittedReadable ":false,"readableListening":false,"resumeScheduled":false,"errorEmitted":false,"emitClose":true,"autoDestroy":true,"destroyed":false,"errored":null,"closed": false,"closeEmitted":false,"defaultEncoding":"utf8","awaitDrainWriters":null,"multiAwaitDrain":false,"readingMore":false,"decoder":null,"encoding":null},"_events" :{},"_eventsCount":1,"_writableState":{"objectMode":false,"highWaterMark":16384,"finalCalled":false,"needDrain":false,"ending":false,"ended":false ,"完成":false,"销毁":false,"decodeStrings":false,"defaultEncoding":"utf8","length":0,"writing":false,"corked":0,"sync":true ,"bufferProcessing":false,"writecb":null,"writelen":0,"afterWriteTickInfo":null,"buffered":[],"bufferedIndex":0,"allBuffers":true,"allNoop":true, "pendingcb":0,"prefinished":false,"errorEmitted":false,"emitClose":true,"autoDestroy":true,"errored":null,"closed":false},"allowHalfOpen":true," offset":1,"_isActive":false,"_parentObj":{"_rowCache":[],"_processingStarted":false,"_convertedToStream":false,"_a llowGetRowCall":false,"_isActive":false,"_parentObj":{"_events":{},"_eventsCount":1,"_dbObjectClasses":{},"_requestQueue":[],"_inProgress":true," _pool":{"_events":{},"_eventsCount":2,"_queueTimeout":60000,"_queueMax":500,"_enableStatistics":false,"edition":"","events":false,"externalAuth ":false,"同质":true,"user":...

Answer 1

总的来说，检查doc和examples。

默认情况下，LOBS 将作为对象返回，您可以从中流式传输，或者可以调用 getData() on。

如果您的 LOB 为 1 GB 或更少，那么您可能希望强制所有 LOB 作为字符串或缓冲区返回。将这些设置在代码的顶部：

oracledb.fetchAsString = [ oracledb.CLOB ];
oracledb.fetchAsBuffer = [ oracledb.BLOB ];

阅读Working with CLOB, NCLOB and BLOB Data 上的文档了解更多详情。

outformat 属性指的是行是用数组还是 JS 对象表示的。没有预定义的常量oracledb.ARRAYBUFFER。或者也许你自己添加了这个常量？