![Layer中被忽略]( "Layer中被忽略")
本文介绍了" WHERE"子图在Google地图中的Fusion Table Layer中被忽略的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图通过API在Google地图中使用Google Fusion表格作为图层。只需使用FusionTableLayer（）将图层添加到Google Map即可正常工作。我可以看到地图和所有。当我尝试对选择查询或样式部分应用过滤器（即where子句）时，fun开始。过滤器不起作用！它不会抛出任何错误。地图不断运作。但是结果集不会被滤除 - 就好像where子句甚至不在那里一样。样式部分使用'where'子句的相同症状。它完全被忽略。我有三种不同的样式，我想根据过滤条件应用。所有这些都被忽略。奇怪的是，样式块中列出的最后一个样式部分应用于融合表层的所有要素。我通过切换周围的部分来验证它。我尝试用像col10这样的引用替换实际的字段名称，但这没有什么区别。
我错过了什么？我如何在我的FusionTableLayer中启用使用WHERE子句，以便它们既可以在Select查询中使用，也可以在Styles部分中使用？
注意：在下面的代码片段，（/）评论插入这篇文章。这些评论不存在于我正在开发的实际页面/代码中。
I am trying to use a Google Fusion table as a layer in Google maps via API. Just adding the layer to the Google Map using FusionTableLayer() works fine. I can see the map and all. The "fun" begins when I try to apply a filter (i.e. a "where clause") to the select query or to the Styles section. The filters just do not work! It does not throw any error. Map keeps on working. But the result set is not filtered down--as if the where clause wasn't even there. The same symptoms for the 'where' clause used for the Styles section. It is completely ignored. I have three different styles, which I want applied based on filter conditions. All of the those are ignored. The strange thing is that the very last style section listed in the Styles block gets applied to ALL features in the fusion table layer. I verified it by switching the sections around. I tried replacing the actual field names by the references like "col10", but that didn't make any difference.
What am I missing? How can I "enable" the use of WHERE clauses in my FusionTableLayer so that they get applied both in the Select query, and also in the Styles sections?
Note: in the code snippet below, the (//) comments were inserted for this post. These comments do not exist in the actual page/code I am developing.
layer = new google.maps.FusionTablesLayer({
map: map,
heatmap: { enabled: false },
query: {
select: "col11",
from: "1D6d93-0iT2zUCw8IvkbpDPYDx2-jA0ZAWXi07mQD",
//the following filter in select query does not work!
//I replaced col10 with actual field name (shift_id) but still EVERYTHING from the table is returned
where: "col10 <= 3"
},
styles: [{
//this where clause has no effect. I've tried replacing shift_id with col10.
where: "((shift_id != 1) AND (shift_id != 2))",
polylineOptions: {
strokeColor: "#FFFFFF",
strokeWeight: "3" }
}, {
//this where clause has no effect. I've tried replacing shift_id with col10.
where: "shift_id == 1",
polylineOptions: {
strokeColor: "#FF0000",
strokeWeight: "3" }
}, {
//this where clause has no effect. I've tried replacing shift_id with col10.
//whichever of these three blocks is listed last is the one that gets applied to the layer.
where: "shift_id == 2",
polylineOptions: {
strokeColor: "#ffbf00",
strokeWeight: "3" }
}]
});
解决方案
- "==" doesn't work, use "="
- don't include the where in the main query
layer = new google.maps.FusionTablesLayer({
map: map,
heatmap: {
enabled: false
},
query: {
select: "geometry",
from: "1D6d93-0iT2zUCw8IvkbpDPYDx2-jA0ZAWXi07mQD",
},
styles: [{
where: "((SHIFT_ID != 1) AND (SHIFT_ID != 2))",
polylineOptions: {
strokeColor: "#FFFFFF",
strokeWeight: "3"
}
}, {
where: "SHIFT_ID = 1",
polylineOptions: {
strokeColor: "#FF0000",
strokeWeight: "3"
}
}, {
where: "SHIFT_ID = 2",
polylineOptions: {
strokeColor: "#ffbf00",
strokeWeight: "3"
}
}]
});
proof of concept fiddle
code snippet:
var geocoder = new google.maps.Geocoder();
var map;
function initialize() {
var map = new google.maps.Map(
document.getElementById("map_canvas"), {
center: new google.maps.LatLng(37.4419, -122.1419),
zoom: 13,
mapTypeId: google.maps.MapTypeId.ROADMAP
});
layer = new google.maps.FusionTablesLayer({
map: map,
heatmap: {
enabled: false
},
query: {
select: "geometry",
from: "1D6d93-0iT2zUCw8IvkbpDPYDx2-jA0ZAWXi07mQD",
},
styles: [{
where: "((SHIFT_ID != 1) AND (SHIFT_ID != 2))",
polylineOptions: {
strokeColor: "#FFFFFF",
strokeWeight: "3"
}
}, {
where: "SHIFT_ID = 1",
polylineOptions: {
strokeColor: "#FF0000",
strokeWeight: "3"
}
}, {
where: "SHIFT_ID = 2",
polylineOptions: {
strokeColor: "#ffbf00",
strokeWeight: "3"
}
}]
});
geocoder.geocode({
'address': "Winnipeg, Canada"
}, function(results, status) {
if (status === google.maps.GeocoderStatus.OK) {
map.fitBounds(results[0].geometry.viewport);
} else {
alert('Geocode was not successful for the following reason: ' + status);
}
});
}
google.maps.event.addDomListener(window, "load", initialize);html,
body,
#map_canvas {
height: 100%;
width: 100%;
margin: 0px;
padding: 0px
}<script src="https://maps.googleapis.com/maps/api/js"></script>
<div id="map_canvas"></div>
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