geojson 遇到的诡异问题

V2EX = way to explore

V2EX 是一个关于分享和探索的地方

现在注册

已注册用户请登录

这是一个创建于 2172 天前的主题，其中的信息可能已经有所发展或是发生改变。

我用 nodejs-v8.15.0 和 tilestrata-2.1.2 搭建了一个地图服务，现在在调试 geojson 的输出，遇到一个诡异的问题。我的后端代码如下：

query=`SELECT ST_ASGEOJSON(ST_INTERSECTION( ST_TRANSFORM(ST_SETSRID(way, 900913),4326) , ST_SETSRID(ST_MAKEENVELOPE(121.5966796875,31.12819929911195,121.61865234375,31.109388560814956), 4326) ) ) AS geometry, tags AS properties FROM planet_osm_roads WHERE ST_INTERSECTS( ST_TRANSFORM(ST_SETSRID(way, 900913),4326), ST_SETSRID(ST_MAKEENVELOPE(121.5966796875,31.12819929911195,121.61865234375,31.109388560814956), 4326) ) AND highway <> ''`;

pgPool.query(query, function(err, result) {
    if (err) {
        console.log(query, err.message, err.stack)
        var err = new Error('An error occurred');
        err.statusCode = 500;
        return callback(err);
    }
      
    var outputText = '{"type":"FeatureCollection","features":[' +
        result.rows.map(function(row) {
          if (row.geometry) {
            var featureString = '{"type":"Feature","geometry":' + row.geometry;
            if (row.properties != ''){
                var rowpro = row.properties;
                rowpro = rowpro.replace(/=>/g,':');
                featureString = featureString + ',"properties":' + '{'+  rowpro + '}}';
            }
            else{
                featureString = featureString + ',"properties":""}';
            }
            delete row;
            return featureString;
          }
    }).join(',') +']}';
    
    //在此处的 outputText 得到的数据是完整的，总共 4372 个字符，也是可以正常解析的
    callback(null, outputText, {'Content-Type': 'application/json'});
});

然后在浏览器中输入 http://192.168.56.180:8767/geojson/14/13726/6700/road.json 你会发现 head 中的 Content-Length 是 4372，但 RAW DATA 中只显示了 4324 个字符，后面的消失了，导致报错：SyntaxError: JSON.parse: unterminated string at line 1 column 4325 of the JSON data

并不是所有的语句都会被截断，但有些就会这样，如果我把 row.properties 这部分代码去除则不会出错，但是加了 row.properties 这部分代码后生成的 outputText 是正确的，一到浏览器那就可能出错，我找不出规律

附：数据来源是 openstreetmap 下载的 shanghai 的 pbf，此问题在我这是可以复现的，浏览器是 chrome-71.0.3578.80 （ 64 位）和 firefox-63.0.3 (64 位),数据是用 osm2pgsql 导入的。

请各位大虾指点迷津，我已经没方向了

7 条回复 • 2018-12-19 21:13:38 +08:00

des

2018-12-19 20:45:25 +08:00 via Android

老哥，能别用拼接的么，很明显是拼 properties 的时候出错了。
比如里边有引号之类的

des

2018-12-19 20:47:10 +08:00 via Android

肉眼难看出错误，你把 outputText 复制出
来找个 json 格式化工具就很明显了

des

2018-12-19 20:48:21 +08:00 via Android

都 8102 年了，还有拼接 json 的

kzfile

2018-12-19 20:53:21 +08:00

要我直接就在 postgis 里用 row_to_json 返回 featurecollection 了.

buxingdebeiju

2018-12-19 20:57:44 +08:00

感谢回复，我将 outputText 复制出来验证过的，格式肯定没错，现在的问题是浏览器端会截断

kzfile

2018-12-19 21:06:06 +08:00

你试过只加适量的吗?osm 数据谁知道有啥乱七八糟的字符

buxingdebeiju

2018-12-19 21:13:38 +08:00

得到的 outputText 内容如下：
{"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6174958,31.1155741996536],[121.6175779,31.1154147996536],[121.6180951,31.1147908996536],[121.61865234375,31.1141186666828]]},"properties":{"name:en":"Kangxin Hwy", "int_name":"Kangxin Hwy"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.598580173598,31.128199299112],[121.5993113,31.1260036996529],[121.5994785,31.125470599653],[121.5996444,31.124930499653],[121.5998067,31.124386899653],[121.5999638,31.1238317996531],[121.6001239,31.1232462996531],[121.6001665,31.1230842996531]]},"properties":{"name:en":"Hufeng Expressway", "name:zh":"沪奉高速", "int_name":"Hufeng Gaosu", "name:zh-hant":"滬奉高速", "name:zh_pinyin":"Hùfèng Gāosù"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6002983,31.1231090996531],[121.6002555,31.1232720996531],[121.6000951,31.1238585996531],[121.5999377,31.124414799653],[121.5997751,31.124959499653],[121.5996089,31.125500299653],[121.5994414,31.1260344996529],[121.598720540595,31.128199299112]]},"properties":{"name:en":"Hufeng Expressway", "name:zh":"沪奉高速", "int_name":"Hufeng Gaosu", "name:zh-hant":"滬奉高速", "name:zh_pinyin":"Hùfèng Gāosù"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6004449,31.1176192996535],[121.6012693,31.1177876996535],[121.6015535,31.1178457996535],[121.6017564,31.1178871996534]]},"properties":{"name:en":"Zhoudeng Hwy", "int_name":"Zhoudeng Hwy"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6009608,31.1193780996534],[121.6011358,31.1184991996534],[121.60121,31.1181036996534],[121.6012693,31.1177876996535]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6015535,31.1178457996535],[121.6014975,31.1181438996534],[121.6014232,31.1185398996534],[121.6012754,31.1192820996534]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6007809,31.1200430996533],[121.6008066,31.1199276996533],[121.600875,31.1196021996533],[121.6009608,31.1193780996534]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6012754,31.1192820996534],[121.6012376,31.1196639996533],[121.6011359,31.1201282996533]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6003394,31.1219540996532],[121.6004978,31.1212930996532],[121.6006523,31.1206222996533],[121.6007809,31.1200430996533]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6011359,31.1201282996533],[121.6010129,31.1206820996533],[121.6008578,31.1213551996532],[121.6006991,31.1220172996532]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6001665,31.1230842996531],[121.6002363,31.1224859996532],[121.6002839,31.1222195996532],[121.6003394,31.1219540996532]]},"properties":{"destination:street":"周邓公路"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6006991,31.1220172996532],[121.600623,31.1222798996532],[121.6005278,31.1225404996532],[121.6002983,31.1231090996531]]},"properties":""},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6173272,31.1159013996536],[121.6174958,31.1155741996536]]},"properties":{"name:en":"Kangxin Hwy", "int_name":"Kangxin Hwy"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6017564,31.1178871996534],[121.6024349,31.1180257996534],[121.608019,31.1191666996534],[121.6153795,31.1206101996533],[121.6179191,31.1211082996532],[121.61865234375,31.1212281916358]]},"properties":{"name:en":"Zhoudeng Hwy", "int_name":"Zhoudeng Hwy"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6139156,31.125504199653],[121.6141751,31.124636599653],[121.6148268,31.1224580996532],[121.6153795,31.1206101996533],[121.6165758,31.1173601996535],[121.6173272,31.1159013996536]]},"properties":{"name:en":"Kangxin Hwy", "int_name":"Kangxin Hwy"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.6137068,31.1262022996529],[121.6139156,31.125504199653]]},"properties":{"name:en":"Kangxin Hwy", "int_name":"Kangxin Hwy"}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[121.613109423394,31.128199299112],[121.6137068,31.1262022996529]]},"properties":{"name:en":"Kangxin Hwy", "int_name":"Kangxin Hwy"}}]}
我用在线工具测试过的