本文实例讲述了nodejs nedb 封装库与使用方法。分享给大家供大家参考，具体如下：
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libs/nedb.js
const Datastore = require('nedb');
function DB(database) {
let options = {
filename: database,
autoload: true,
};
this.db = new Datastore(options);
}
DB.prototype.limit = function(offset, limit) {
this.offset = offset || 0;
this.limit = limit || 15;
return this;
}
DB.prototype.sort = function(orderby) {
this.orderby = orderby;
return this;
}
DB.prototype.find = function(query, select) {
return new Promise((resolve, reject) => {
let stmt = this.db.find(query || {});
if (this.orderby !== undefined) {
stmt.sort(this.orderby);
}
if (this.offset !== undefined) {
stmt.skip(this.offset).limit(this.limit);
}
if (select != undefined) {
stmt.projection(select || {});
}
stmt.exec((err, docs) => {
if (err) {
return reject(err);
}
resolve(docs);
})
})
};
DB.prototype.findOne = function(query, select) {
return new Promise((resolve, reject) => {
let stmt = this.db.findOne(query || {});
if (this.sort !== undefined) {
stmt.sort(this.sort);
}
if (select != undefined) {
stmt.projection(select || {});
}
stmt.exec((err, doc) => {
if (err) {
return reject(err);
}
resolve(doc);
})
})
}
DB.prototype.insert = function(values) {
return new Promise((resolve, reject) => {
this.db.insert(values, (err, newDoc) => {
if (err) {
return reject(err);
}
resolve(newDoc);
})
})
}
DB.prototype.update = function(query, values, options) {
return new Promise((resolve, reject) => {
this.db.update(query || {}, values || {}, options || {}, (err, numAffected) => {
if (err) {
return reject(err);
}
resolve(numAffected);
})
});
}
DB.prototype.remove = function(query, options) {
return new Promise((resolve, reject) => {
this.db.remove(query || {}, options || {}, (err, numAffected) => {
if (err) {
return reject(err);
}
resolve(numAffected);
})
});
}
module.exports = (database) => {
return new DB(database);
}
test.js
const db = require('./libs/nedb')('testdb');
(async function() {
await db.insert({number: 12});
await db.insert({number: 11});
await db.insert({number: 13});
let res = await db.sort({number: -1}).limit(0, 2).find();
console.log(res);
})();
执行命令
nodemon test.js
希望本文所述对大家node.js程序设计有所帮助。
