Index Attachments

The index:

• To index attachments' details, call attachmentsFor() within the index definition.

• attachmentsFor() provides access to the name, size, hash, and content-type of each attachment a document has. These details can then be used when defining the index-fields.

• To index attachments' content, see the examples below.

class Employees_ByAttachmentDetails extends AbstractJavaScriptIndexCreationTask {
    constructor () {
        super();

        const { attachmentsFor } = this.mapUtils();

        this.map("employees", employee => {
            // Call 'attachmentsFor' to get attachments details
            const attachments = attachmentsFor(employee);

            return {
                // Can index info from document properties:
                employeeName: employee.FirstName + " " + employee.LastName,

                // Index DETAILS of attachments:
                attachmentNames: attachments.map(x => x.Name),
                attachmentContentTypes: attachments.map(x => x.ContentType),
                attachmentSizes: attachments.map(x => x.Size)
            }
        });
    }
}

Query the Index:

You can now query for Employee documents based on their attachments details.

const employees = await session
     // Query the index for matching employees
    .query({ indexName: "Employees/ByAttachmentDetails" })
     // Filter employee results by their attachments details
    .whereEquals("attachmentNames", "photo.jpg")
    .whereGreaterThan("attachmentSizes", 20_000)
    .all();

// Results:
// ========
// Running this query on the Northwind sample data,
// results will include 'employees/4-A' and 'employees/5-A'.
// These 2 documents contain an attachment by name 'photo.jpg' with a matching size.

from index "Employees/ByAttachmentDetails"
where attachmentNames == "photo.jpg" and attachmentSizes > 20000

Sample data:

• Each Employee document in the Northwind sample data already includes a photo.jpg attachment.

• For all following examples, let's store a textual attachment (file notes.txt) on 3 documents
  in the 'Employees' collection.

const session = documentStore.openSession();

for (let i = 1; i <= 3; i++) {
    // Load an employee document:
    const employee = await session.load(`employees/${i}-A`);
    
    // Store the employee's notes as an attachment on the document:
    const stream = Buffer.from(employee.Notes[0]);
    session.advanced.attachments.store(`employees/${i}-A`, "notes.txt", stream, "text/plain");
}

await session.saveChanges();

The index:

• To index the details & content for a specific attachment, call loadAttachment() within the index definition.

• In addition to accessing the attachment details, loadAttachment() provides access to the attachment's content, which can be used when defining the index-fields.

class Employees_ByAttachment extends AbstractJavaScriptIndexCreationTask {
    constructor () {
        super();

        const { loadAttachment } = this.mapUtils();

        this.map("employees", employee => {
            // Call 'loadAttachment' to get attachment's details and content
            // pass the attachment name, e.g. "notes.txt"
            const attachment = loadAttachment(employee, "notes.txt");

            return {
                // Index DETAILS of attachment:
                attachmentName: attachment.Name,
                attachmentContentType: attachment.ContentType,
                attachmentSize: attachment.Size,

                // Index CONTENT of attachment:
                // Call 'getContentAsString' to access content
                attachmentContent: attachment.getContentAsString()
            }
        });

        // It can be useful configure Full-Text search on the attachment content index-field
        this.index("attachmentContent", "Search");

        // Documents with an attachment named 'notes.txt' will be indexed,
        // allowing you to query them by either the attachment's details or its content.
    }
}

Query the Index:

You can now query for Employee documents based on their attachment details and/or its content.

const employees = await session
    // Query the index for matching employees
    .query({indexName: "Employees/ByAttachment"})
    // Can make a full-text search
    // Looking for employees with an attachment content that contains 'Colorado' OR 'Dallas'
    .search("attachmentContent", "Colorado Dallas")
    .all();

// Results:
// ========
// Results will include 'employees/1-A' and 'employees/2-A'.
// Only these 2 documents have an attachment by name 'notes.txt'
// that conains either 'Colorado' or 'Dallas'.

from index "Employees/ByAttachment"
where search(attachmentContent, "Colorado Dallas")

The index:

• Use loadAttachments() to be able to index the details & content of ALL attachments.

• Note how the index example below is employing the Fanout index pattern.

class Employees_ByAllAttachments extends AbstractJavaScriptIndexCreationTask {
    constructor () {
        super();

        const { loadAttachments } = this.mapUtils();

        this.map("employees", employee => {
            // Call 'loadAttachments' to get details and content for ALL attachments
            const allAttachments = loadAttachments(employee);

            // This will be a Fanout index -
            // the index will generate an index-entry for each attachment per document

            return allAttachments.map(attachment => ({

                // Index DETAILS of attachment:
                attachmentName: attachment.Name,
                attachmentContentType: attachment.ContentType,
                attachmentSize: attachment.Size,

                // Index CONTENT of attachment:
                // Call 'getContentAsString' to access content
                attachmentContent: attachment.getContentAsString()
            }));
        });

        // It can be useful configure Full-Text search on the attachment content index-field
        this.index("attachmentContent", "Search");
    }
}

Query the Index:

const employees = await session
    // Query the index for matching employees
    .query({indexName: "Employees/ByAllAttachments"})
    // Filter employee results by their attachments details and content
    .whereGreaterThan("attachmentSize", 20_000)
    .orElse()
    .search("attachmentContent", "Colorado Dallas")
    .all();

// Results:
// ========
// Results will include:
// 'employees/1-A' and 'employees/2-A' that match the content criteria 
// 'employees/4-A' and 'employees/5-A' that match the size criteria

from index "Employees/ByAllAttachments"
where attachmentSize > 20000 or search(attachmentContent, "Colorado Dallas")