Indexes: Map Indexes

Let's create an index that will help us search for Employees by their FirstName, LastName, or both.

• First, let's create an index called Employees/ByFirstAndLastName

class Employees_ByFirstAndLastName extends AbstractCsharpIndexCreationTask {
    // ...
}

• The next step is to create the indexing function itself. This is done by setting the map field with mapping function in the constructor.

constructor() {
    super();

    this.map = `from employee in docs.Employees
        select new { 
           FirstName = employee.FirstName,     
           LastName = employee.LastName 
        }`;
}

• The final step is to deploy it to the server and issue a query using the session Query method:

const employees1 = await session.query({ indexName: "Employees/ByFirstAndLastName" })
    .whereEquals("FirstName", "Robert")
    .all();

const employees2 = await session.query({ indexName: "Employees/ByFirstAndLastName" })
    .whereEquals("FirstName", "Robert")
    .all();

from index 'Employees/ByFirstAndLastName'
where FirstName = 'Robert'

`from employee in docs.Employees
select new
{
	Age = employee.Age
}`

`from employee in docs.Employees
select new
{
	Age = employee.Age.ToString()
}`

`from employee in docs.Employees
select new
{
    FirstName = employee.FirstName,
    LastName = employee.LastName
}`

Since each index contains a LINQ function, you can combine multiple fields into one.

Example I

class Employees_ByFullName extends AbstractCsharpIndexCreationTask {
    constructor() {
        super();

        this.map = `from employee in docs.Employees
            select new { 
               Name = employee.FirstName + ' ' + employee.LastName
            }`;
    }
}

const employees = await session
    .query({ indexName: "Employees/ByFullName" })
    .whereEquals("FullName", "Robert King")
    .ofType(Employee)
    .all();

from index 'Employees/ByFullName'
where FullName = 'Robert King'

Example II

class Employees_Query extends AbstractCsharpIndexCreationTask {
    constructor() {
        super();

        this.map = `from employee in docs.Employees
            select new {     
            Query = new [] { 
                employee.FirstName, 
                employee.LastName, 
                employee.Title, 
                employee.Address.City 
            } 
        }`;

        this.index("Query", "Search");
    }
}

const employees = await session
    .query({ indexName: "Employees/Query" })
    .search("Query", "John Doe")
    .ofType(Employee)
    .all();

from index 'Employees/Query'
where search(Query, 'John Doe')

Imagine that you would like to return all employees that were born in a specific year. You can do it by indexing Birthday from Employee in the following way:

class Employees_ByBirthday extends AbstractCsharpIndexCreationTask {

    constructor() {
        super();

        this.map = `from employee in docs.Employees
            select new {     
                Birthday = employee.Birthday,
            }`;
    }

}

const startDate = new Date(1963, 1, 1);
const endDate = new Date(1963, 12, 31, 23, 59, 59, 999);
const employees = await session
    .query({ indexName: "Employees/ByBirthday" })
    .whereBetween("Birthday", startDate, endDate)
    .ofType(Employee)
    .all();

from index 'Employees/ByBirthday '
where Birthday between '1963-01-01' and '1963-12-31T23:59:59.9990000'

RavenDB gives you the ability to extract field data and to index by it. A different way to achieve our goal will look as follows:

class Employees_ByYearOfBirth extends AbstractCsharpIndexCreationTask {

    constructor() {
        super();

        this.map = `from employee in docs.Employees
            select new { 
               YearOfBirth = employee.Birthday.Year,     
            }`;
    }
}

const employees = await session
    .query({ indexName: "Employees/ByYearOfBirth" })
    .whereEquals("YearOfBirth", 1963)
    .ofType(Employee)
    .all();

from index 'Employees/ByYearOfBirth'
where YearOfBirth = 1963

If your document contains nested data, e.g. Employee contains Address, you can index on its fields by accessing them directly in the index. Let's say that we would like to create an index that returns all employees that were born in a specific Country:

class Employees_ByCountry extends AbstractCsharpIndexCreationTask {

    constructor() {
        super();

        this.map = `from employee in docs.Employees
            select new {      
            Country = employee.Address.Country 
        }`;
    }
}

const employees = await session
    .query({ indexName: "Employees/ByCountry" })
    .whereEquals("Country", "USA")
    .ofType(Employee)
    .all();

from index 'Employees/ByCountry'
where Country = 'USA'

If a document relationship is represented by the document's ID, you can use the LoadDocument method to retrieve such a document. More about it can be found here.

By default, indexes will not index a document that contains none of the specified fields. This behavior can be changed using the Indexing.IndexEmptyEntries configuration option.

The option Indexing.IndexMissingFieldsAsNull determines whether missing fields in documents are indexed with the value null, or not indexed at all.