使用JSONStream读取大型JSON文件

Question

我一直在尝试使用JSONStream读取文件，但我在这方面没有太多经验，而且很难找到有关它的信息(教程、文档)。

我在这里的某个地方发现了这段代码：

var fs = require('fs'),
    JSONStream = require('JSONStream');

var stream = fs.createReadStream('tst.json', {encoding: 'utf8'}),
    parser = JSONStream.parse();

stream.pipe(parser);

console.log(parser);

parser.on('root', function (obj) {
  console.log(obj); // whatever you will do with each JSON object
});

我尝试将其用于json测试文件，如下所示：

{
    "colors": [{
            "color": "black",
            "category": "hue",
            "type": "primary",
            "code": {
                "rgba": [255, 255, 255, 1],
                "hex": "#000"
            }
        },
        {
            "color": "white",
            "category": "value",
            "code": {
                "rgba": [0, 0, 0, 1],
                "hex": "#FFF"
            }
        },
        {
            "color": "red",
            "category": "hue",
            "type": "primary",
            "code": {
                "rgba": [255, 0, 0, 1],
                "hex": "#FF0"
            }
        },
        {
            "color": "blue",
            "category": "hue",
            "type": "primary",
            "code": {
                "rgba": [0, 0, 255, 1],
                "hex": "#00F"
            }
        },
        {
            "color": "yellow",
            "category": "hue",
            "type": "primary",
            "code": {
                "rgba": [255, 255, 0, 1],
                "hex": "#FF0"
            }
        },
        {
            "color": "green",
            "category": "hue",
            "type": "secondary",
            "code": {
                "rgba": [0, 255, 0, 1],
                "hex": "#0F0"
            }
        }
    ]
}

我以为它会返回所有的对象，但是什么都没有发生，它甚至没有出现在"parser.on('root'，function (Obj))“中。我能做些什么来让它工作呢？

Answer 1

已从JSONStream中删除root事件。请改用data事件。https://github.com/dominictarr/JSONStream/commit/97d973ac59d0e58748cec98ea87aae36e057d368

还应该将JSON path指定为JSONStream.parse()的参数。对于JSON，它可以是JSONStream.parse('colors.*')。

所以把所有的东西放在一起，应该是

var fs = require('fs'),
    JSONStream = require('JSONStream');

var stream = fs.createReadStream('tst.json', {encoding: 'utf8'}),
    parser = JSONStream.parse('colors.*');

stream.pipe(parser);

parser.on('data', function (obj) {
  console.log(obj); // whatever you will do with each JSON object
});