借助地点自动补全数据 API,您可以以编程方式提取地点预测,从而打造自定义自动补全体验,并且控制程度比自动补全 widget 更精细。在本指南中,您将学习如何使用地点自动填充数据 API 根据用户查询发出自动填充请求。
以下示例展示了一个简单的预测性输入集成。输入您的搜索查询,然后点击以选择所需的结果。
“自动填充”请求
自动补全请求会接受查询输入字符串,并返回地点预测结果列表。如需发出自动补全请求,请调用 fetchAutocompleteSuggestions()
并传递包含所需属性的请求。input
属性包含要搜索的字符串;在典型的应用中,此值会在用户输入查询时更新。请求应包含 sessionToken
,用于结算目的。
以下代码段展示了如何创建请求正文并添加会话令牌,然后调用 fetchAutocompleteSuggestions()
以获取 PlacePrediction
的列表。
// Add an initial request body. let request = { input: "Tadi", locationRestriction: { west: -122.44, north: 37.8, east: -122.39, south: 37.78, }, origin: { lat: 37.7893, lng: -122.4039 }, includedPrimaryTypes: ["restaurant"], language: "en-US", region: "us", }; // Create a session token. const token = new AutocompleteSessionToken(); // Add the token to the request. // @ts-ignore request.sessionToken = token;
限制自动补全预测结果
默认情况下,地点自动补全服务会显示所有地点类型(偏向于用户所在位置附近的预测结果),并提取用户所选地点的所有可用数据字段。通过限制或自定义调整结果来设置地点自动补全选项,可以显示更相关的预测结果。
限制预测结果会导致 Autocomplete widget 忽略限制区域以外的任何结果。常见做法是将结果范围限定在地图边界内。自定义调整结果会使 Autocomplete widget 显示指定区域内的结果,但某些匹配项可能不在这个指定区域内。
使用 origin
属性指定用于计算到目的地的测地线距离的起点。如果省略此值,系统将不返回距离。
使用 includedPrimaryTypes
属性最多可指定 5 种地点类型。
如果未指定任何类型,系统将返回所有类型的地点。
获取地点详情
如需从地点预测结果返回 Place
对象,请先调用 toPlace()
,然后对生成的 Place
对象调用 fetchFields()
(系统会自动包含地点预测中的会话 ID)。调用 fetchFields()
会结束自动补全会话。
let place = suggestions[0].placePrediction.toPlace(); // Get first predicted place. await place.fetchFields({ fields: ["displayName", "formattedAddress"], }); const placeInfo = document.getElementById("prediction"); placeInfo.textContent = "First predicted place: " + place.displayName + ": " + place.formattedAddress;
会话令牌
会话令牌将用户自动补全搜索的查询和选择阶段归入不同的会话,以便进行结算。会话在用户开始输入时开始。 当用户选择地点并执行对“地点详情”的调用时,会话即结束。
如需创建新的会话令牌并将其添加到请求中,请创建 AutocompleteSessionToken
的实例,然后设置请求的 sessionToken
属性以使用令牌,如以下代码段所示:
// Create a session token. const token = new AutocompleteSessionToken(); // Add the token to the request. // @ts-ignore request.sessionToken = token;
调用 fetchFields()
时,会话结束。创建 Place
实例后,您无需将会话令牌传递给 fetchFields()
,因为系统会自动处理此操作。
await place.fetchFields({ fields: ["displayName", "formattedAddress"], });
await place.fetchFields({ fields: ['displayName'], });
通过创建 AutocompleteSessionToken
的新实例,为下一个会话创建会话令牌。
会话令牌建议:
- 针对所有地点自动补全调用使用会话令牌。
- 为每个会话生成一个新的令牌。
- 为每个新会话传递唯一的会话令牌。针对多个会话使用同一令牌会导致每个请求被单独计费。
您可以选择从请求中省略自动补全会话令牌。如果省略会话令牌,系统会对每个请求单独结算,从而触发自动补全 - 按请求结算 SKU。如果您重复使用某个会话令牌,相应会话会被视为无效,并且系统会按未提供会话令牌的情况为请求计费。
示例
当用户输入查询时,系统会每隔几次按键(而非按字符)调用一次自动补全请求,并返回可能的结果列表。当用户从结果列表中进行选择时,该选择会计为一次请求,并且搜索期间发出的所有请求都会捆绑在一起,计为一次请求。如果用户选择某个地点,则搜索查询是免费的,只有地点数据请求需要付费。如果用户在会话开始后的几分钟内未做出选择,系统只会收取搜索查询费用。
从应用的角度来看,事件流程如下所示:
- 用户开始输入查询,搜索“法国巴黎”。
- 检测到用户输入后,应用会创建一个新的会话令牌“令牌 A”。
- 用户输入字符时,API 会每输入几个字符就发出一次自动补全请求,并针对每个字符显示一个新的可能结果列表:
“P”
“Par”
“Paris,”
“Paris, Fr”
- 当用户进行选择时:
- 查询产生的所有请求都会被分组,并作为单个请求添加到由“令牌 A”表示的会话中。
- 系统会将用户的选择计为一次地点详情请求,并将其添加到由“令牌 A”表示的会话中。
- 会话结束,应用舍弃“令牌 A”。
完整示例代码
本部分包含完整示例,展示了如何使用地点自动补全数据 API。地点自动补全预测结果
以下示例演示了针对输入“Tadi”调用 fetchAutocompleteSuggestions()
,然后对第一个预测结果调用 toPlace()
,最后调用 fetchFields()
以获取地点详情。
TypeScript
/** * Demonstrates making a single request for Place predictions, then requests Place Details for the first result. */ async function init() { // @ts-ignore const { Place, AutocompleteSessionToken, AutocompleteSuggestion } = await google.maps.importLibrary("places") as google.maps.PlacesLibrary; // Add an initial request body. let request = { input: "Tadi", locationRestriction: { west: -122.44, north: 37.8, east: -122.39, south: 37.78 }, origin: { lat: 37.7893, lng: -122.4039 }, includedPrimaryTypes: ["restaurant"], language: "en-US", region: "us", }; // Create a session token. const token = new AutocompleteSessionToken(); // Add the token to the request. // @ts-ignore request.sessionToken = token; // Fetch autocomplete suggestions. const { suggestions } = await AutocompleteSuggestion.fetchAutocompleteSuggestions(request); const title = document.getElementById('title') as HTMLElement; title.appendChild(document.createTextNode('Query predictions for "' + request.input + '":')); for (let suggestion of suggestions) { const placePrediction = suggestion.placePrediction; // Create a new list element. const listItem = document.createElement('li'); const resultsElement = document.getElementById("results") as HTMLElement; listItem.appendChild(document.createTextNode(placePrediction.text.toString())); resultsElement.appendChild(listItem); } let place = suggestions[0].placePrediction.toPlace(); // Get first predicted place. await place.fetchFields({ fields: ['displayName', 'formattedAddress'], }); const placeInfo = document.getElementById("prediction") as HTMLElement; placeInfo.textContent = 'First predicted place: ' + place.displayName + ': ' + place.formattedAddress; } init();
JavaScript
/** * Demonstrates making a single request for Place predictions, then requests Place Details for the first result. */ async function init() { // @ts-ignore const { Place, AutocompleteSessionToken, AutocompleteSuggestion } = await google.maps.importLibrary("places"); // Add an initial request body. let request = { input: "Tadi", locationRestriction: { west: -122.44, north: 37.8, east: -122.39, south: 37.78, }, origin: { lat: 37.7893, lng: -122.4039 }, includedPrimaryTypes: ["restaurant"], language: "en-US", region: "us", }; // Create a session token. const token = new AutocompleteSessionToken(); // Add the token to the request. // @ts-ignore request.sessionToken = token; // Fetch autocomplete suggestions. const { suggestions } = await AutocompleteSuggestion.fetchAutocompleteSuggestions(request); const title = document.getElementById("title"); title.appendChild( document.createTextNode('Query predictions for "' + request.input + '":'), ); for (let suggestion of suggestions) { const placePrediction = suggestion.placePrediction; // Create a new list element. const listItem = document.createElement("li"); const resultsElement = document.getElementById("results"); listItem.appendChild( document.createTextNode(placePrediction.text.toString()), ); resultsElement.appendChild(listItem); } let place = suggestions[0].placePrediction.toPlace(); // Get first predicted place. await place.fetchFields({ fields: ["displayName", "formattedAddress"], }); const placeInfo = document.getElementById("prediction"); placeInfo.textContent = "First predicted place: " + place.displayName + ": " + place.formattedAddress; } init();
CSS
/* * Always set the map height explicitly to define the size of the div element * that contains the map. */ #map { height: 100%; } /* * Optional: Makes the sample page fill the window. */ html, body { height: 100%; margin: 0; padding: 0; }
HTML
<html> <head> <title>Place Autocomplete Data API Predictions</title> <link rel="stylesheet" type="text/css" href="./style.css" /> <script type="module" src="./index.js"></script> </head> <body> <div id="title"></div> <ul id="results"></ul> <p><span id="prediction"></span></p> <img class="powered-by-google" src="https://storage.googleapis.com/geo-devrel-public-buckets/powered_by_google_on_white.png" alt="Powered by Google" /> <!-- prettier-ignore --> <script>(g=>{var h,a,k,p="The Google Maps JavaScript API",c="google",l="importLibrary",q="__ib__",m=document,b=window;b=b[c]||(b[c]={});var d=b.maps||(b.maps={}),r=new Set,e=new URLSearchParams,u=()=>h||(h=new Promise(async(f,n)=>{await (a=m.createElement("script"));e.set("libraries",[...r]+"");for(k in g)e.set(k.replace(/[A-Z]/g,t=>"_"+t[0].toLowerCase()),g[k]);e.set("callback",c+".maps."+q);a.src=`https://maps.${c}apis.com/maps/api/js?`+e;d[q]=f;a.onerror=()=>h=n(Error(p+" could not load."));a.nonce=m.querySelector("script[nonce]")?.nonce||"";m.head.append(a)}));d[l]?console.warn(p+" only loads once. Ignoring:",g):d[l]=(f,...n)=>r.add(f)&&u().then(()=>d[l](f,...n))}) ({key: "AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg", v: "weekly"});</script> </body> </html>
试用示例
带会话的地点自动补全提前输入功能
此示例演示了如何根据用户查询调用 fetchAutocompleteSuggestions()
,以响应显示预测地点列表,最后检索所选地点的地点详情。该示例还演示了如何使用会话令牌将用户查询与最终的地点详情请求分组。
TypeScript
let title; let results; let input; let token; // Add an initial request body. let request = { input: "", locationRestriction: { west: -122.44, north: 37.8, east: -122.39, south: 37.78 }, origin: { lat: 37.7893, lng: -122.4039 }, includedPrimaryTypes: ["restaurant"], language: "en-US", region: "us", }; async function init() { token = new google.maps.places.AutocompleteSessionToken(); title = document.getElementById('title'); results = document.getElementById('results'); input = document.querySelector("input"); input.addEventListener("input", makeAcRequest); request = refreshToken(request) as any; } async function makeAcRequest(input) { // Reset elements and exit if an empty string is received. if (input.target.value == '') { title.innerText = ''; results.replaceChildren(); return; } // Add the latest char sequence to the request. request.input = input.target.value; // Fetch autocomplete suggestions and show them in a list. // @ts-ignore const { suggestions } = await google.maps.places.AutocompleteSuggestion.fetchAutocompleteSuggestions(request); title.innerText = 'Query predictions for "' + request.input + '"'; // Clear the list first. results.replaceChildren(); for (const suggestion of suggestions) { const placePrediction = suggestion.placePrediction; // Create a link for the place, add an event handler to fetch the place. const a = document.createElement('a'); a.addEventListener('click', () => { onPlaceSelected(placePrediction!.toPlace()); }); a.innerText = placePrediction!.text.toString(); // Create a new list element. const li = document.createElement('li'); li.appendChild(a); results.appendChild(li); } } // Event handler for clicking on a suggested place. async function onPlaceSelected(place) { await place.fetchFields({ fields: ['displayName', 'formattedAddress'], }); let placeText = document.createTextNode(place.displayName + ': ' + place.formattedAddress); results.replaceChildren(placeText); title.innerText = 'Selected Place:'; input.value = ''; refreshToken(request); } // Helper function to refresh the session token. async function refreshToken(request) { // Create a new session token and add it to the request. token = new google.maps.places.AutocompleteSessionToken(); request.sessionToken = token; return request; } declare global { interface Window { init: () => void; } } window.init = init;
JavaScript
let title; let results; let input; let token; // Add an initial request body. let request = { input: "", locationRestriction: { west: -122.44, north: 37.8, east: -122.39, south: 37.78, }, origin: { lat: 37.7893, lng: -122.4039 }, includedPrimaryTypes: ["restaurant"], language: "en-US", region: "us", }; async function init() { token = new google.maps.places.AutocompleteSessionToken(); title = document.getElementById("title"); results = document.getElementById("results"); input = document.querySelector("input"); input.addEventListener("input", makeAcRequest); request = refreshToken(request); } async function makeAcRequest(input) { // Reset elements and exit if an empty string is received. if (input.target.value == "") { title.innerText = ""; results.replaceChildren(); return; } // Add the latest char sequence to the request. request.input = input.target.value; // Fetch autocomplete suggestions and show them in a list. // @ts-ignore const { suggestions } = await google.maps.places.AutocompleteSuggestion.fetchAutocompleteSuggestions( request, ); title.innerText = 'Query predictions for "' + request.input + '"'; // Clear the list first. results.replaceChildren(); for (const suggestion of suggestions) { const placePrediction = suggestion.placePrediction; // Create a link for the place, add an event handler to fetch the place. const a = document.createElement("a"); a.addEventListener("click", () => { onPlaceSelected(placePrediction.toPlace()); }); a.innerText = placePrediction.text.toString(); // Create a new list element. const li = document.createElement("li"); li.appendChild(a); results.appendChild(li); } } // Event handler for clicking on a suggested place. async function onPlaceSelected(place) { await place.fetchFields({ fields: ["displayName", "formattedAddress"], }); let placeText = document.createTextNode( place.displayName + ": " + place.formattedAddress, ); results.replaceChildren(placeText); title.innerText = "Selected Place:"; input.value = ""; refreshToken(request); } // Helper function to refresh the session token. async function refreshToken(request) { // Create a new session token and add it to the request. token = new google.maps.places.AutocompleteSessionToken(); request.sessionToken = token; return request; } window.init = init;
CSS
/* * Always set the map height explicitly to define the size of the div element * that contains the map. */ #map { height: 100%; } /* * Optional: Makes the sample page fill the window. */ html, body { height: 100%; margin: 0; padding: 0; } a { cursor: pointer; text-decoration: underline; color: blue; } input { width: 300px; }
HTML
<html> <head> <title>Place Autocomplete Data API Session</title> <link rel="stylesheet" type="text/css" href="./style.css" /> <script type="module" src="./index.js"></script> </head> <body> <input id="input" type="text" placeholder="Search for a place..." /> <div id="title"></div> <ul id="results"></ul> <img class="powered-by-google" src="https://storage.googleapis.com/geo-devrel-public-buckets/powered_by_google_on_white.png" alt="Powered by Google" /> <!-- The `defer` attribute causes the script to execute after the full HTML document has been parsed. For non-blocking uses, avoiding race conditions, and consistent behavior across browsers, consider loading using Promises. See https://developers.google.com/maps/documentation/javascript/load-maps-js-api for more information. --> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=init&libraries=places&v=weekly" defer ></script> </body> </html>