Angular 服务和 pouchdb

Question

如何使用 angularjs 服务调用 pouchdb 并将数据返回给控制器？我一直在开发一个带有 pouchdb 的离子应用程序，用于本地存储。我有一个内置在控制器中的简单 crud 应用程序。现在我想开始将 pouchdb 调用移动到服务中。我无法从服务中取回数据。我将如何使用服务调用 pouchdb 来获取所有文档并将其返回给控制器？

Answer 1

我认为可以很好地用于 Angular 服务的一种策略是this one。它描述了一种保持内存数组与 PouchDB 的 allDocs() 的结果同步的方法。

由于它是一个自动与 PouchDB 保持同步的数组，因此您只需在其上执行 ng-repeat，即可完成。 :)

Answer 2

虽然您的问题已有一年之久，但值得回答。

您可能需要多个服务，即一个用于控制器，另一个用于后端数据库存储。例如在控制器中：

(function () {
    'use strict';

    angular
        .module('app.services')
        .factory('db',db);

    db.$inject = ['$db'];

    function db($db) {

        var data = {};              // set up a data object to receive document(s)

        return {
            getDoc: getDoc,
            getList: getList,
            save: save,
            saveBatch: saveBatch
            };


        // get a single document using the id
        function getDoc(id) {
            $db.getDoc(id)
                .then(
                    function onSuccess(doc) {
                        // success so update the view model
                        angular.extend(data,doc);                         // use angular.extend to shallow copy object so that it can be returned in full
                    },
                    function onError() {
                        // failure to get document                             
                    }
                );
            return data;
        }

        // retrieve a group of documents where key is the prefix of the data you want
        function getList(key) {
            $db.getList(key).then(
                function onSuccess(docs) {
                    // success so update the view model details
                    angular.forEach(docs.rows, function (value) {
                        this.push(value.doc);
                    }, data);
                    // now you can sort data or anything else you want to do with it

                },
                function onError() {
                    // no data found
                }
            );
            return data;
        }


        // save a single viewItem
        function save(viewItem) {
            $db.update(viewItem).then(
                function onSuccess() {                   
                    // success so update view model if required
                },
                function onError(e) {
                    console.log(e);         // unable to save
                }    
            );    
        }

        // save an array of viewItems
        function saveBatch(viewItems) {
            $db.updateBatch(viewItems).then(
                function onSuccess() {                   
                    // success so update the view model if required
                },
                function onError(e) {
                    console.log(e);         // unable to save
                }    
            );    
        }

    }
})();

对于后端，类似这样：

(function () {
    'use strict';

    angular
        .module('app.services')
        .factory('$db',$db);

    $db.$inject = ['$q'];

    function $db($q) {

        var db;

        return {
            setLocalDB: setLocalDB,
            update: update,
            updateBatch: updateBatch,
            getDoc: getDoc,
            getAllDocs: getAllDocs,
            getList: getList
        };

    // ------ DATABASE OPENING HANDLER(S) ------

        // set to any named database
       function setLocalDB(dbName) {
            db = new PouchDB(dbName);
            return db.info()
                .catch(failedCheck());             // returns a promise to either work or fail
        }

        // return a rejection for a failure
        function failedCheck() {
            return $q.reject();
        }

    // ------ DOCUMENT HANDLING ------     

        // update document but if errors occur recurse qUpdate until either complete or retries exhausted
        function update(doc) {
            var counter = 0;
            return $q.when(qUpdate(doc,counter));
        }

        // this routine works for both new and existing documents
        function qUpdate(doc,counter) {
            return db.put(doc)
                .then(function() {
                    console.log('success - new document');                 
                })
                .catch(function(e) { 
                    console.log(e);                     // not a new document so try as a revision of existing document using _id to find
                    return db.get(doc._id)
                        .then(function(origDoc) {
                            doc._rev = origDoc._rev;                    // get document revision _rev
                            return db.put(doc,doc._id,doc._rev)
                                .then(function() {
                                    console.log('success - revision of document');
                                })
                                .catch(function(e){
                                    console.log(e);             // log error for failure
                                });
                        })
                        .catch(function(e){
                            console.log(e);                     // log error before we take any other action
                            counter ++;                         // increment counter, so we can limit retries (5 by default)
                            if (counter< 5) {
                                switch (e.status) {
                                    case 404:
                                        delete doc._rev;                        // remove revision information so we can see if this works
                                        return qUpdate(doc);                    // might be deleted so return revised document for retry                 
                                    case 409:
                                        return qUpdate(doc);                    // in conflict so try again
                                    default:
                                        try {
                                            throw new Error("cannot save: " + doc._id);     // cannot go any further so throw new error   
                                        } catch(err) {
                                            console.log(err);                               // log error for failure
                                        } 
                                }
                            } else {
                                try {
                                    throw new Error("cannot save" + doc._id);   // cannot go any further so throw new error 
                                } catch(err) {
                                    console.log(err);                           // log error for failure
                                } 
                            }
                        });    
                    });   
        }

        // update a document batch stored in an array
        function updateBatch(docs) {
            return $q.when(qUpdateBatch(docs));
        }

        // do the actual update of a batch
        function qUpdateBatch(docs) {
            db.bulkDocs(docs).then(function(res) {
                for (var i=0; i < res.length; i++) {
                    if (res[i].status === 409) {
                        update(docs[i]);                 // in conflict so try this document separately
                    }
                }
            }).catch(function(e){
                console.log(e);                         // log error
            });  
        }

        // get the document as an angular promise and deal with it in host routine
        function getDoc(id)  {
            return $q.when(db.get(id));
        }

        // get all documents
        function getAllDocs() {
            return $q.when(db.allDocs({include_docs: true, attachments: false})); 
        }

        // get a batch of documents between a start and end key
        function getList(key) {
            return $q.when(db.allDocs({startkey: key, endkey: key + '\uffff', include_docs: true, attachments: false})); 
        }
    }
})();

在您的主控制器中，您需要设置数据库：

   $db.setLocalDB('yourDB'); 

希望这就是您要找的吗？

在我自己的数据服务模块中，我还有远程数据库、事件监听器、删除、同步、压缩、销毁等功能。