解析云代码 geoPoint 查询 Javascript 语法

Question

我正在尝试编写一个 Parse Cloud Code 函数，其中参数是一个对象列表，每个对象都包含一个 geoPoint 成员。对于列表中的每个项目，我将在 Parse 数据存储中搜索 1 英里半径内具有相同名称的现有项目。如果项目不存在，则创建项目并将其保存到数据存储。

我的函数

/**
 *  Take a list of Place and check for existence in Parse.
 *  If it doesn't already exist, add it.
 *  @see https://www.parse.com/questions/access-distance-on-a-geoquery
 *  @param {JSON Place.PlaceSearch}
 *  @return none
 */
 function addConvertedApiResult(placeData) {
    for ( var i = 0; i < placeData.length; i++ ) {
        // look near loc for existing name
        var loc = new Parse.GeoPoint(placeData[i].lat, placeData[i].lon)

        var query = new Parse.Query("Place");
        query.withinMiles("location", loc, 1);
        query.equalTo("name", placeData[i].name);

        console.log("placeData[i].name:"+placeData[i].name);
        query.find({
            success: function(results) {
                // results contains a list of places that are within 1 mile
                // and have the same name
                console.log("results.length = "+results.length);
                if(results.length < 1) {
                    // add the place
                    var Place = Parse.Object.extend("Place");
                    var place = new Place();

                    place.set("en", placeData[i].name);
                    place.set("location", loc);
                    place.set("moreInfo", placeData[i].moreInfo);

                    place.save();
                }
            },
            error: function(error) {
                // There was an error.
                console.log("error = "+error.message);
            }
        });

        console.log("leaving addConvertedApiResult");
    }
}

我对调用 addConvertedApiResult 的云函数的请求

（必须从 windows 命令行转义 '"'）

curl -X POST 
-H "X-Parse-Application-Id: <key>" 
-H "X-Parse-REST-API-Key: <key>" -H "Content-Type: application/json" 
-d "{\"name\":\"Storm+Mountain\",\"lat\":44.0760,\"lon\":-103.2280,\"limit\":5,\"radius\":25}" https://api.parse.com/1/functions/getPlace
{"result":[{"lat":43.95483,"lon":-103.36869,"moreInfo":"<apiUrl>/item.php?c=1\u0026i=3439","name":"Storm Mountain"}]}

生成的解析信息日志

I2015-03-03T05:56:26.905Z] v99: Ran cloud function getPlace with:
  Input: {"lat":44.0760,"limit":5,"lon":-103.2280,"name":"Storm+Mountain","radius":25}
  Result: [{"name":"Storm Mountain","lat":43.95483,"lon":-103.36869,"moreInfo":"<moreInfoUrl>"}]

I2015-03-03T05:56:27.434Z] placeData[i].name:Storm Mountain

I2015-03-03T05:56:27.435Z] leaving addConvertedApiResult

数据存储中有 4 个现有点应返回，但其中 none 个具有相同的名称。该函数似乎没有执行 query.find 方法。我没有看到来自 success: 或 error: 函数的日志消息。如果我理解正确，这些函数应该允许我对查询结果执行代码。

如果 console.log 似乎不起作用，我如何确认查询没有结果？

我一直在网上尝试此语法的不同变体。我的语法正确吗？

谢谢。

更新

我一直在研究这个问题，很高兴了解 Promises。不幸的是，我的情况没有改变。我现在从 addConvertedApiResult 函数中调用这些函数。我已经 tested/debugged 他们使用 Chrome 开发者工具在本地 javascript 文件中编写了一个驱动程序，一切运行良好。但是，当我将此代码部署到 Parse Cloud 时，代码执行似乎在我调用 .find() 后消失在以太中。

我知道 CC 上的代码执行是异步的，但我的印象是使用 .then() 函数应该可以克服该限制。

我希望有人能向我解释我所缺少的东西。

谢谢。

/**
 *  Take a Place and check for existence in Parse.
 *  If it doesn't already exist, add it.
 *  @see https://www.parse.com/questions/access-distance-on-a-geoquery
 *  @see https://parse.com/docs/js_guide#promises-chaining
 *  @param {JSON Place.PlaceSearch}
 *  @return none
 */
function addNewPlace(place) {
    // look near loc for already existing place with same name
    var loc = new Parse.GeoPoint(place.lat, place.lon)
    var query = new Parse.Query('Place');
    query.withinMiles('location', loc, 1);
    query.equalTo('en', place.name);
    query.find().then( function(results) {
        if(results.length < 1) {
            console.log(place.name+" does not exist")
            var Place = Parse.Object.extend("Place");
            var newPlace = new Place();

            var loc = new Parse.GeoPoint(place.lat, place.lon)
            newPlace.set('en', place.name);
            newPlace.set('location', loc);
            newPlace.set('moreinfo', place.moreinfo);

            return newPlace.save();
        }
    });
}

/**
 *  Take a list of Place and check for existence in Parse.
 *  If it doesn't already exist, add it.
 *  @see https://www.parse.com/questions/access-distance-on-a-geoquery
 *  @see https://parse.com/docs/js_guide#promises-chaining
 *  @param {JSON Place.PlaceSearch}
 *  @return none
 */
function addConvertedApiResult(placeData) {
    var _ = require('underscore');

    console.log("placeData.legth:"+placeData.length);
    _.each(placeData, function(place) {
        addNewPlace(place);
    });
}

Answer 1

我上面提供的代码片段在语法上是正确的。不过，我的问题是，我花了一段时间才完全理解从 CloudCode 对 Parse 和其他 API 进行顺序异步调用编程的概念。最终，我能够使用一个函数和使用以下模式的一串承诺来完成我想要的。

someCall( function(someObject) {
    // do some stuff
    return result;

}).then( function(resultOfPrev) {
    // do some more stuff
    return result;

}).then( function(resultOfPrev) {
    // create some nested promises

    // Create a trivial resolved promise as a base case.
    var queryPromise = Parse.Promise.as();

    _.each(resultsOfPrev, function(thing) {
        // For each item, extend the promise with a function to ...
        queryPromise = queryPromise.then( function() {

            var query = new Parse.Query(Thing);
            query.equalTo("name", thing.name);

            return query.find().then( function(result) {

                var savePromise = Parse.Promise.as();
                savePromise = savePromise.then( function() {

                    var saved = false;
                    if(result.length < 1) {
                        // then save the thing
                        var newThing =  new Thing();
                        newThing.set('name', thing.name);
                        return newThing.save();
                    } else {
                        return false;
                    }
                });

                return savePromise;
            });
        });
    });

    return queryPromise;

}).then( function(resultsOfPrev) {
    // response must not be called until
    // the end of the chain.
    response.success( resultsOfPrev);

}.then( function() {
    // i realy don't understand why but,
    // I need this empty function at the 
    // tail of the chain.
});

解析云代码 geoPoint 查询 Javascript 语法

Parse Cloud Code geoPoint Query Javascript Syntax

javascript

parse-platform

parse-cloud-code

geopoints