如何使用 PHP 修改 Google 地图的大型 json 结构

Question

我有一个 Google 地图，使用 Google 地图 API 从 .json 文件中绘制折线。文件结构的一部分可以在下面看到，它只是为每个折线特征重复。它是在 GIS 中创建并转换为 .geojson 然后 json.

我希望允许用户通过映射界面修改功能的特定属性。我已经构建了界面和用户交互，但在修改 .json 文件时遇到问题。

我试过以下方法：

PHP（注意：我将一些值硬编码为 test/get 它可以工作 ）

$jsonString = file_get_contents('../json/hartford.json');
$data = json_decode($jsonString, true);

foreach ($data as $key => $entry) {
    if ($entry['UID'] == 25301) {
        $data[$key]['RENDER_CL'] = "99";
    }
}

$newJsonString = json_encode($data);
file_put_contents('../json/hartford.json', $newJsonString);

错误：

警告：非法字符串偏移 'UID' 在线...

注意：未定义索引：在线UID...

想法：

我觉得我对 json "tree" 的了解还不够深入，无法访问属性。我之前没有修改过 json 数据，所以我有点迷茫。我应该以某种方式更深入地研究结构吗？每个项目的 UID 都是唯一的。谢谢。

JSON 文件

{
"type": "FeatureCollection",
"crs": {
    "type": "name",
    "properties": {
        "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
    }
},
"features": [{
    "type": "Feature",
    "properties": {
        "FULLNAME": "I-84 E",
        "RENDER_CL": 0,
        "FCC": "Highway",
        "clicked": "no",
        "UID": 25301
    },
    "geometry": {
        "type": "MultiLineString",
        "coordinates": [[[-72.70621818192563523552962578833103179931640625, 41.7494854544135023388662375509738922119140625], [-72.7059645455619971698979497887194156646728515625, 41.74953636350443275659927166998386383056640625], [-72.7057163637438179648597724735736846923828125, 41.749591818049879066165885888040065765380859375], [-72.705553636471080380943021737039089202880859375, 41.749633636231692435103468596935272216796875], [-72.7053663637438063460649573244154453277587890625, 41.749688181686252619329025037586688995361328125], [-72.705190909198364579424378462135791778564453125, 41.749742727140784381845151074230670928955078125], [-72.70496727283472182534751482307910919189453125, 41.749821818049866806177305988967418670654296875], [-72.704716363743813190012588165700435638427734375, 41.749924545322613766984432004392147064208984375], [-72.70461181828926555681391619145870208740234375, 41.74996818168625623002299107611179351806640625]]]
    }
}, {
    "type": "Feature",
    "properties": {
        "FULLNAME": "I-84 E",
        "RENDER_CL": 0,
        "FCC": "Highway",
        "clicked": "no",
        "UID": 25302
    },
    "geometry": {
        "type": "MultiLineString",
        "coordinates": [[[-72.7150890910165372815754381008446216583251953125, 41.749747272595328695388161577284336090087890625], [-72.7141218182892572485798154957592487335205078125, 41.7496918180498823858215473592281341552734375]]]
    }
},

Answer 1

您正在错误地访问对象的属性。正确的方法是 $entry['properties']['UID'].

例子

<?php

$json =
    '{
        "type": "Feature",
        "properties": {
            "FULLNAME": "I-84 E",
            "RENDER_CL": 0,
            "FCC": "Highway",
            "clicked": "no",
            "UID": 25302
        },
        "geometry": {
            "type": "MultiLineString",
            "coordinates": [[[-72.7150890910165372815754381008446216583251953125, 41.749747272595328695388161577284336090087890625], [-72.7141218182892572485798154957592487335205078125, 41.7496918180498823858215473592281341552734375]]]
        }
    }';

$obj = json_decode($json, true);

print $obj['properties']['UID'];

如何使用 PHP 修改 Google 地图的大型 json 结构

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例子