Working With Futon : Creating Custom Map Function -Tutorial Savvy

“FUTON” is a web interface for couch db.
It can be viewed in “5984” port of the system.
In the my previous post(link) we have seen how to install and create a database in couch db.
In another previous post(link) we have seen how to access the content of a database (“student”) in java using couchdb4j library.
Here we are going to learn a new concept called “VIEW” in couch db.
Views are used for two purposes in couch db .Those are Querying and Reporting.
Temporary view and Permanent View are two types of views in couch db.
In this Demo, “We are going to create a MAP function in Futon.The name of the function say getAllStudentName, It will return the names of student with their id“.
The Existing “student” database is like(in Futon), Here 4 students are present ,

Changing the view in futon to temporary view,

The Temporary view looks like,

“emit” is the function will returns the value on each document.It takes two argument “key” and “value“.
Lets write a function in the editor to return the name of students,

/*Retrieves All the Student Names*/
function(document) {

    var nameOfStudent;

    if (document.name) {
        
            nameOfStudent = [document.name];

            emit(document._id,nameOfStudent);

        }
    
}

The Editor’s Screenshot,

Save this script as getAllStudentNames,

After Saving it will be listed in the drop down,

Now Run This getAllStudentName map function. The output looks like,

The Object view of the output,

{"total_rows":4,"offset":0,"rows":[
{"id":"326e49164d9b414a6c1ce2c8a802d175","key":"326e49164d9b414a6c1ce2c8a802d175","value":["sandeep"]},
{"id":"326e49164d9b414a6c1ce2c8a802d28e","key":"326e49164d9b414a6c1ce2c8a802d28e","value":["sumanta"]},
{"id":"326e49164d9b414a6c1ce2c8a802dda1","key":"326e49164d9b414a6c1ce2c8a802dda1","value":["sangeeta"]},
{"id":"326e49164d9b414a6c1ce2c8a802f200","key":"326e49164d9b414a6c1ce2c8a802f200","value":["Surabhi"]}
]}

In couch db everything is treated as document. The best proof is , you can see this function is listed in all_document section in the bottom. The screen shot,

This map function inside look like,

Feb 20, 2013Sandeep

Working With Futon : Creating Custom Map Function

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Sandeep