node.js\u3067MongoDB\u4e0a\u306eGridFS\u304b\u3089\u30d5\u30a1\u30a4\u30eb\u3092\u30c0\u30a6\u30f3\u30ed\u30fc\u30c9\u3059\u308b\u306e\u306b\u624b\u9593\u53d6\u3063\u305f\u306e\u3067\u3001\u30e1\u30e2\u3002<\/p>\n\n\n\n
\u3084\u308a\u305f\u304b\u3063\u305f\u306e\u306f\u3001MongoDB\u4e0a\u306eGridFS\u304b\u3089\u30a4\u30e1\u30fc\u30b8\u30d5\u30a1\u30a4\u30eb\u30c7\u30fc\u30bf\u3092\u53d6\u5f97\u3057\u3066\u3001\u30c7\u30fc\u30bfURL\u3092\u4f5c\u308a\u305f\u304b\u3063\u305f\u3060\u3051\u3060\u3051\u3069\u3001node.js\u306eMongoDB Driver\u306eGridFSBucketReadStream\u306eread\u30e1\u30bd\u30c3\u30c9\u304c\u3001\u975e\u540c\u671f\u52d5\u4f5c\u3057\u304b\u3067\u304d\u306a\u3044\u3088\u3046\u3067\u3001\u8272\u3005\u82e6\u52b4\u3057\u305f\u30fb\u30fb\u30fb<\/p>\n\n\n\n
\u7d50\u5c40\u3001read\u5468\u8fba\u306e\u90e8\u5206\u3092promise\u3092\u4f7f\u7528\u3057\u3066\u3001async funciton\u306b\u3059\u308b\u4e8b\u3067\u3068\u308a\u3042\u3048\u305a\u3001\u4e00\u898b\u843d\u7740\u3002<\/p>\n\n\n\n
var mongo = require('mongodb');\nvar buffer = require('buffer');\n\u30fb\u30fb\u30fb\nlet fs = new mongo.GridFSBucket(db);\n\/\/ ObjectId\u3092\u4f7f\u7528\u3057\u3066GridFSBucketReadStream\u3092\u5f97\u308b\nvar stm = fs.openDownloadStream(ObjectId("xxx\u30fb\u30fb\u30fb"));\n\/\/ \u540c\u671f\u7684\u306b\u30a4\u30e1\u30fc\u30b8\u30d5\u30a1\u30a4\u30eb\u30c7\u30fc\u30bf\u53d6\u5f97\nvar body = await ReadAsync(stm);\nvar imgUrl = 'data:image\/jpeg;base64,' + buffer.Buffer.from(body).toString('base64');\n\n\/\/\n\/\/ GridFSBucketReadStream\u304b\u3089\u540c\u671f\u7684\u306b(\u898b\u3048\u308b\u3088\u3046\u306b)\u30c7\u30fc\u30bf\u53d6\u5f97\n\/\/\t\u623b\u308a\u5024:Promise<Buffer>\n\/\/\nasync function ReadAsync(stm) {\n return new Promise((resolve,reject) => {\n try {\n var totalsize = 0; \/\/ \u8aad\u307f\u53d6\u3063\u305f\u30c8\u30fc\u30bf\u30eb\u30b5\u30a4\u30ba\n var chunks = []; \/\/ \u8aad\u307f\u53d6\u3063\u305fchunk\n \/\/ \u30c7\u30fc\u30bf\u53d6\u5f97\u6642\u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u5b9a\u7fa9\n stm.on('data',\n (v) => {\n \/\/ \u8aad\u8fbc\u3093\u3060\u30c7\u30fc\u30bf(chunk)\u3092\u4fdd\u5b58\n var buf = buffer.Buffer.from(v);\n chunks.push(buf);\n totalsize += buf.length;\n }\n );\n \/\/ \u30c7\u30fc\u30bf\u7d42\u4e86\u6642\u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u5b9a\u7fa9\n stm.on('end',\n () => {\n \/\/ \u7d50\u5408\u5148\u306eBuffer\u3092\u4f5c\u6210\n var ximage = buffer.Buffer.alloc(totalsize);\n \/\/ \u5168chunk\u306e\u7d50\u5408\n var offset = 0;\n for(var i=0; i < chunks.length; i++) {\n chunks[i].copy(ximage,offset);\n offset += chunks[i].length;\n }\n \/\/ \u8aad\u8fbc\u3093\u3060\u30c7\u30fc\u30bf\u3092\u8fd4\u3059\n resolve(ximage);\n }\n );\n \/\/ \u8aad\u8fbc\u53ef\u6642\u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u5b9a\u7fa9\n stm.on('readable',\n \/\/ \u8aad\u8fbc\u958b\u59cb\n ()=> stm.read()\n );\n } catch (err) {\n reject(err);\n }\n });\n}<\/code><\/pre><\/div>\n\n\n\n\u89e3\u6c7a\u3059\u308b\u307e\u3067\u306b\u3061\u3087\u3063\u3068\u6642\u9593\u304c\u639b\u304b\u3063\u305f\u306a\u3041\u30fb\u30fb\u30fb<\/p>\n\n\n\n
\u3053\u308c\u304c\u6b63\u89e3\u304b\u3069\u3046\u304b\u306f\u5206\u304b\u3089\u306a\u3044\u3051\u3069\u3001\u53d6\u6562\u3048\u305a\u52d5\u3044\u3066\u3044\u308b\u304b\u3089\u3044\u3044\u3084\u3002<\/p>\n\n\n\n
\u6b63\u898f\u306e\u30e9\u30a4\u30d6\u30e9\u30ea\u306b\u3082await stm.read()\u3067\u547c\u3073\u51fa\u3055\u305b\u308b\u3088\u3046\u306a\u30e1\u30bd\u30c3\u30c9\u7528\u610f\u3057\u3066\u304a\u3044\u3066\u6b32\u3057\u3044\u306a\u3002<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
node.js\u3067MongoDB\u4e0a\u306eGridFS\u304b\u3089\u30d5\u30a1\u30a4\u30eb\u3092\u30c0\u30a6\u30f3\u30ed\u30fc\u30c9\u3059\u308b\u306e\u306b … \u7d9a\u304d\u3092\u8aad\u3080