从 MySql 在 php 中创建 GeoJson 以与 MapBox javascript API 一起使用

Posted 2023-02-24

【中文标题】从 MySql 在 php 中创建 GeoJson 以与 MapBox javascript API 一起使用

【英文标题】：Creating a GeoJson in php from MySql to use with MapBox javascript API

【发布时间】：2013-07-20 11:35:06

【问题描述】：

我想做的很简单；使用我的 php 代码从 mysql 表中获取标记的数据，将其转换为 geoJson（由 MapBox 使用），将该 geoJson 发送到 javascript，然后将这些标记填充到我的地图中。

我一直在非常仔细地阅读以下两个链接，其中显然包含解决此问题所需的所有信息，但我不确定我缺少什么。

Here 你可以看到一个如何从 MapBox 中的 geoJson 填充标记的示例；

Here你可以看到如何从MySql表中创建geoJson；

我的sql表是这样的，这里是创建代码加上一些虚拟数据；

-- phpMyAdmin SQL Dump
-- version 4.0.4.1
-- http://www.phpmyadmin.net
--
-- Host: localhost
-- Generation Time: Jul 21, 2013 at 03:26 PM
-- Server version: 5.5.32-cll-lve
-- PHP Version: 5.5.0

SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";

--
-- Database: `pgmq`
--

-- --------------------------------------------------------

--
-- Table structure for table `mapa`
--

CREATE TABLE IF NOT EXISTS `mapa` (
  `contrato` int(11) NOT NULL,
  `name` varchar(60) NOT NULL,
  `address` varchar(80) NOT NULL,
  `lat` float(10,6) NOT NULL,
  `lng` float(10,6) NOT NULL,
  `type` varchar(30) NOT NULL,
  PRIMARY KEY (`contrato`),
  UNIQUE KEY `contrato` (`contrato`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

--
-- Dumping data for table `mapa`
--

INSERT INTO `mapa` (`contrato`, `name`, `address`, `lat`, `lng`, `type`) VALUES
(217, 'DIVANIR  BRASIL DA SILVA', '47 joao carolino da silva, guaruja - sao paulo, brazil', -23.950968, -46.289585, '11'),
(233, 'ADEMIR  VIEIRA', '180 dois j, guaruja - sao paulo, brazil', -23.932041, -46.206879, '11'),
(241, 'MARIA CECILIA  DOS SANTOS', '81 professor carvalho pinto, guaruja - sao paulo, brazil', -23.946516, -46.290428, '11'),
(252, 'ELIETE  COSTA SANTOS', '387 maria de melo rodrigues, guaruja - sao paulo, brazil', -23.667521, -46.747810, '11'),
(271, 'ROBERTO  SANTOS COUTO', '62 tapajos, guaruja - sao paulo, brazil', -23.949146, -46.284588, '11'),
(275, 'UMBERTO FERREIRA  SOUZA NETO', '88 tapajos, guaruja - sao paulo, brazil', -23.949162, -46.284821, '11'),
(276, 'SERGIO RICARDO  DOS SANTOS', '418 joana menezes de mello faro, guaruja - sao paulo, brazil', -23.994600, -46.256866, '11'),
(278, 'MARIA APARECIDA  NUNES', '80 andre reboucas, guaruja - sao paulo, brazil', -23.945040, -46.297462, '11'),
(285, 'WALTECES SOUZA  DA CONCEICAO', '298 maranhao, guaruja - sao paulo, brazil', -23.942638, -46.304131, '11'),
(286, 'ROBERTO AUGUSTO  DE JESUS SOUZA', '38 dois c  caic cinquenta e cinco , guaruja - sao paulo, brazil', -23.994600, -46.256866, '11');

这是我的 php 代码，我从数据库中获取数据并创建一个 GeoJson。

<?php

$connect = mysql_connect("localhost","user","password");

$mapa = "SELECT * FROM pgmq.mapa ";

$dbquery = mysql_query($mapa,$connect);

$geojson = array( 'type' => 'FeatureCollection', 'features' => array());

while($row = mysql_fetch_assoc($dbquery))

$marker = array(
                'type' => 'Feature',
                'features' => array(
                    'type' => 'Feature',
                    'properties' => array(
                        'title' => "".$row[name]."",
                        'marker-color' => '#f00',
                        'marker-size' => 'small'
                        //'url' => 
                        ),
                    "geometry" => array(
                        'type' => 'Point',
                        'coordinates' => array( 
                                        $row[lat],
                                        $row[lng]
                        )
                    )
                )
    );
array_push($geojson['features'], $marker['features']);

?>

只是为了测试一下，如果这里的“echo json_encode($marker)”是一个示例输出；

"type":"Feature","features":"type":"Feature","properties":"title":"DIVANIR  BRASIL DA SILVA","marker-color":"#f00","marker-size":"small","geometry":"type":"Point","coordinates":"[-23.950968, -46.289585]";

现在是 javascript 代码的样子；

<script>
var map = L.mapbox.map('map', 'examples.map-20v6611k').setView([-23.948714, -46.295508], 1);

// The GeoJSON representing the two point features

var geoJson = <?php echo json_encode($marker,JSON_NUMERIC_CHECK); ?>;

// Pass features and a custom factory function to the map
map.markerLayer.setGeoJSON(geoJson);
map.markerLayer.on('click', function(e) 
    e.layer.unbindPopup();
    window.open(e.layer.feature.properties.url);
);
</script>

最后是实际显示地图但不显示标记的完整 html；

<?php
    $connect = mysql_connect("localhost","user","pass");

    $mapa = "SELECT * FROM pgmq.mapa ";

    $dbquery = mysql_query($mapa,$connect);

    $geojson = array( 'type' => 'FeatureCollection', 'features' => array());

    while($row = mysql_fetch_assoc($dbquery))

    $marker = array(
                    'type' => 'Feature',
                    'features' => array(
                        'type' => 'Feature',
                        'properties' => array(
                            'title' => "".$row[name]."",
                            'marker-color' => '#f00',
                            'marker-size' => 'small'
                            //'url' => 
                            ),
                        "geometry" => array(
                            'type' => 'Point',
                            'coordinates' => array( 
                                            $row[lat],
                                            $row[lng]
                            )
                        )
                    )
        );
    array_push($geojson['features'], $marker['features']);
    
?>

<!DOCTYPE html>
<html>
<head>
  <meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no' />
  <script src='//api.tiles.mapbox.com/mapbox.js/v1.3.1/mapbox.js'></script>
  <link href='//api.tiles.mapbox.com/mapbox.js/v1.3.1/mapbox.css' rel='stylesheet' />
  <style>
    body  margin:0; padding:0; 
    #map  position:absolute; top:0; bottom:0; width:100%; 
  </style>
</head>
    <body>
    <div id='map'></div>
        <script>
        var map = L.mapbox.map('map', 'examples.map-20v6611k').setView([-23.948714, -46.295508], 1);

        // The GeoJSON representing the two point features

        var geoJson = <?php echo json_encode($marker,JSON_NUMERIC_CHECK); ?>;

        // Pass features and a custom factory function to the map
        map.markerLayer.setGeoJSON(geoJson);
        map.markerLayer.on('click', function(e) 
            e.layer.unbindPopup();
            window.open(e.layer.feature.properties.url);
        );
        </script>
    </body>
</html>

那么，我错过了什么？我注意到的一件事是我的 geoJson 的输出在几何数组中有 "，而在 MapBox 示例中使用的那个没有；

var geoJson = 
    type: 'FeatureCollection',
    features: [
        type: 'Feature',
        properties: 
            title: 'Washington, D.C.',
            'marker-color': '#f00',
            'marker-size': 'large',
            url: 'http://en.wikipedia.org/wiki/Washington,_D.C.'
        ,
        geometry: 
            type: 'Point',
            coordinates: [-77.03201, 38.90065]
        
    ,
    
        type: 'Feature',
        properties: 
            title: 'Baltimore, MD',
            'marker-color': '#f00',
            'marker-size': 'large',
            url: 'http://en.wikipedia.org/wiki/Baltimore'
        ,
        geometry: 
            type: 'Point',
            coordinates: [-76.60767, 39.28755]
        
    ]
;

谁能帮助我？没有任何真正的复杂性，我认为这只是数据格式问题或我将 GeoJson 发送到 JS 的方式。

提前致谢！

我刚刚注意到这一行；

var geoJson = <?php echo json_encode($marker,JSON_NUMERIC_CHECK); ?>;

应该是；

var geoJson = <?php echo json_encode($geojson,JSON_NUMERIC_CHECK); ?>;

在这种情况下，结果是；

    var map = L.mapbox.map('map', 'examples.map-20v6611k').setView([-23.948714, -46.295508], 1);

    // The GeoJSON representing the two point features

    var geoJson = ;

    // Pass features and a custom factory function to the map
    map.markerLayer.setGeoJSON(geoJson);
    map.markerLayer.on('click', function(e) 
        e.layer.unbindPopup();
        window.open(e.layer.feature.properties.url);
    );

【问题讨论】：

你返回的是一个数组而不是 Json 数据

好的，你能解释一下如何改为返回json数据吗？

【参考方案1】：

看看这个：https://github.com/bmcbride/PHP-Database-GeoJSON

您返回的是数组而不是 Json 数据。应该是这样的

<?php
/*
 * Title:   MySQL Points to GeoJSON
 * Notes:   Query a MySQL table or view of points with x and y columns and return the results in GeoJSON format, suitable for use in OpenLayers, Leaflet, etc.
 * Author:  Bryan R. McBride, GISP
 * Contact: bryanmcbride.com
 * GitHub:  https://github.com/bmcbride/PHP-Database-GeoJSON
 */

# Connect to MySQL database
$conn = new PDO('pgsql:host=localhost;dbname=mypostgisdb','myusername','mypassword');

# Build SQL SELECT statement including x and y columns
$sql = 'SELECT *, x AS x, y AS y FROM mytable';

/*
* If bbox variable is set, only return records that are within the bounding box
* bbox should be a string in the form of 'southwest_lng,southwest_lat,northeast_lng,northeast_lat'
* Leaflet: map.getBounds().pad(0.05).toBBoxString()
*/
if (isset($_GET['bbox']) || isset($_POST['bbox'])) 
    $bbox = explode(',', $_GET['bbox']);
    $sql = $sql . ' WHERE x <= ' . $bbox[2] . ' AND x >= ' . $bbox[0] . ' AND y <= ' . $bbox[3] . ' AND y >= ' . $bbox[1];


# Try query or error
$rs = $conn->query($sql);
if (!$rs) 
    echo 'An SQL error occured.\n';
    exit;


# Build GeoJSON feature collection array
$geojson = array(
   'type'      => 'FeatureCollection',
   'features'  => array()
);

# Loop through rows to build feature arrays
while ($row = $rs->fetch(PDO::FETCH_ASSOC)) 
    $properties = $row;
    # Remove x and y fields from properties (optional)
    unset($properties['x']);
    unset($properties['y']);
    $feature = array(
        'type' => 'Feature',
        'geometry' => array(
            'type' => 'Point',
            'coordinates' => array(
                $row['x'],
                $row['y']
            )
        ),
        'properties' => $properties
    );
    # Add feature arrays to feature collection array
    array_push($geojson['features'], $feature);


header('Content-type: application/json');
echo json_encode($geojson, JSON_NUMERIC_CHECK);
$conn = NULL;
?>

【参考方案2】：

你已经接近了，并且在正确的轨道上：

我注意到的一件事是我的 geoJson 的输出在几何数组中有 "，而在 MapBox 示例中使用的那个没有；

是的，您需要消除这些引号！查看示例输出，您将得到一个字符串，而不是数组中“坐标”键的值的数组。

根据您的示例代码，我不确定为什么会出现这种情况，但这样的事情应该可以工作：

$geojson = array( 'type' => 'FeatureCollection', 'features' => array());

while($row = mysql_fetch_assoc($dbquery))

  $marker = array(
    'type' => 'Feature',
    'properties' => array(
      'title' => $row['name'],
      'marker-color' => '#f00',
      'marker-size' => 'small'
    ),
    'geometry' => array(
      'type' => 'Point',
      'coordinates' => array( 
        $row['lat'],
        $row['lng']
      )
    )
  );
  array_push($geojson['features'], $marker);

【参考方案3】：

检查这一行

//表示两点特征的GeoJSON

var geoJson = ;

// 将特征和自定义工厂函数传递给地图

尝试在 php 输出周围添加引号

var geoJson = '';

【参考方案4】：

$marker = array(
                   'type' => 'Feature',
                    //'features' => array(
                        //'type' => 'Feature',
                        'properties' => array(
                            'title' => $row->name,
                            'marker-color' =>'#0F8C29',
                            'marker-size' => 'small'
                            //'url' => 
                            ),
                        "geometry" => array(
                            'type' => 'Point',
                            'coordinates' => array( 
                                            $row->lng,
                                            $row->lat
                            )
                        )
                    //)
        );

    array_push($geojson['features'], $marker);