This framework allows you to write the Linq queries on MongoDB documents.
It supports delayed execution, means query will get fired when any operation(e.g. ToArray,ForEach,First,Take,Skip etc) is performed on the linq query.
It converts the Linq/Sql query to MongoDB query, which helps to improve the code readability.
Example
Please check the below examples.
var linqToMongodb = require('linq-to-mongodb');
var connectionString ="mongodb://172.26.9.15:27017/DB_NAME"
var context = new linqToMongodb.DataContext(connectionString);
context.$.Name="amit";
context.GetTable("Users").Where(_user=>_user.UserName==Name).ToArray(users=>{
//Here you will get all the users which has user name equals to 'amit'
})
Pass the name of documents to GetTable method of context. In above case name of document is "Users" ( Note : it is case sensitive).
Please note the line number 4. if you forgot to add the line 4 i.e 'context.$.Name="amit";' then it wouldn't work.
Here is hack every time when your using the variable in linq query we have to add the property to "context.
quot; object.
Take a look at another example.
function getUsers(age){
var linqToMongodb = require('linq-to-mongodb');
var connectionString ="mongodb://172.26.9.15:27017/DB_NAME"
var context = new linqToMongodb.DataContext(connectionString);
context.$.userAge=age;
context.GetTable("Users").Where(_user=>_user.Age>userAge).ToArray(users=>{
// Here you will get all the users which has age greater than
// the value of the parameter passed to function i.e value of age
})
}
If you can see I have created the new property "userAge"( Note: this property name can be anything) to the object "context.quot;
and assigned the value of parameter i.e "age" to the "userAge".
Then I have used the same parameter name ("userAge") in the where clause "...Where(_user=>_user.Age>userAge)".
To Insert the records.
function addUser(_user){
var linqToMongodb = require('linq-to-mongodb');
var connectionString ="mongodb://172.26.9.15:27017/DB_NAME"
var context = new linqToMongodb.DataContext(connectionString);
context.GetTable("Users").Insert(_user,(result)=>{
//result will provide the value of "_id" which is autogenerated.
});
}
To Update the records.
function UpdateUser(user,callback){
var context = new linqToMongodb.DataContext(connectionString);
context.$.id=user._id;
var $this = this;
var obj={};
obj['Designation']=user.Designation;
obj['Project']=user.Project
context.GetTable("Users").Where(a=>a._id==id).Update({ $set : obj },function(_obj){
callback(_obj)
});
}
Below are the supported Linq Queries.
Select e.g. context.GetTable("Users").Select(new {UserName:1,UserAge:1})
Where e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge)
Count e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Count(cnt=>{ });
Skip e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Skip(10)
Take e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Take(10)
Min e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Min(user=>user.userAge);
Max e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Max(user=>user.userAge);
Sum e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Sum(user=>user.userAge);
Avg e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).Avg(user=>user.userAge);
OrderBy e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).OrderBy(user=>user.userAge);
OrderByDescending e.g. context.GetTable("Users").Where(_user=>_user.Age>userAge).OrderByDescending(user=>user.userAge);
GroupBy e.g. context.GetTable("Users").GroupBy(new {userAge:1})
Distinct e.g. context.GetTable("Users").Distinct(_user=>_user.Age>userAge)
First e.g. context.GetTable("Users").First(_user=>_user.Age>userAge,(user)=>{})
Last e.g. context.GetTable("Users").Last(_user=>_user.Age>userAge,(user)=>{})