Generate Tables from Collection Data Leave feedback

Overview

Tables are one of the most common ways to display structured data in documents. GroupDocs.Assembly for Java makes it easy to generate dynamic tables by iterating over collections and populating table rows with data.

The main classes involved are:

DocumentAssembler - assembles documents
DataSourceInfo - wraps data sources

Here are the steps to generate tables from collections:

Create a table in your template document with a header row
Add a data band row using <<foreach>> syntax to iterate over your collection
Reference collection item members in table cells
Close the data band with <</foreach>>
Assemble the document with your collection data

Note
Table-row data bands automatically repeat the table row for each item in the collection, creating a complete table with all data rows.

Generate Table from Java Object Collection

Create a table from a collection of custom objects:

import com.groupdocs.assembly.*;

public class Product
{
    private final String name;
    private final double price;
    private final int quantity;

    public Product(String name, double price, int quantity)
    {
        this.name = name;
        this.price = price;
        this.quantity = quantity;
    }

    public String getName() { return name; }
    public double getPrice() { return price; }
    public int getQuantity() { return quantity; }
}

public static void generateTableFromCollection() throws Exception
{
    // Create sample data
    Product[] products =
    {
        new Product("Laptop", 999.99, 5),
        new Product("Mouse", 29.99, 20),
        new Product("Keyboard", 79.99, 15)
    };

    // Assemble document
    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument("TableTemplate.docx", "TableOutput.docx",
        new DataSourceInfo(products, "products"));

    System.out.println("Table generated successfully.");
}

Note
Because of Java type erasure, the engine cannot determine the item type of a java.util.List passed directly as a data source, so calling item methods such as getName() fails. Pass an array (as shown above), or expose the list through a getter of a wrapper object (for example, public List<Product> getProducts()) and iterate over it in the template: <<foreach [in data.getProducts()]>>.

Template Structure for Tables

In your template document (TableTemplate.docx), create a table with this structure:

Product Name	Price	Quantity
`<<foreach [in products]>><<[getName()]>>`	`<<[getPrice()]>>`	`<<[getQuantity()]>><</foreach>>`

The opening <<foreach>> tag must be placed at the beginning of the first cell of the data row, and the closing <</foreach>> tag at the end of the last cell, so that the data band spans the entire row. Members of Java objects are accessed through their getter methods. After assembly, you’ll get:

Product Name	Price	Quantity
Laptop	999.99	5
Mouse	29.99	20
Keyboard	79.99	15

Generate Table with Formatting

You can format table cell values using format strings:

import com.groupdocs.assembly.*;

public static void generateFormattedTable() throws Exception
{
    Product[] products =
    {
        new Product("Laptop", 999.99, 5),
        new Product("Mouse", 29.99, 20)
    };

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument("TableTemplate.docx", "FormattedTable.docx",
        new DataSourceInfo(products, "products"));
}

Template with formatting:

Product Name	Price	Quantity
`<<foreach [in products]>><<[getName()]>>`	`<<[getPrice()]:"$#,##0.00">>`	`<<[getQuantity()]>><</foreach>>`

The :"$#,##0.00" format string formats the price as currency (for example, $999.99). Number format strings follow the java.text.DecimalFormat pattern syntax, and the decimal and grouping separators depend on the current locale.

Generate Table from DataTable

You can also generate tables from a DataTable:

import com.groupdocs.assembly.*;
import com.groupdocs.assembly.system.data.*;

public static void generateTableFromDataTable() throws Exception
{
    // Create DataTable
    DataTable productsTable = new DataTable("Products");
    productsTable.getColumns().add("Name", String.class);
    productsTable.getColumns().add("Price", Double.class);
    productsTable.getColumns().add("Quantity", Integer.class);

    // Add rows
    productsTable.getRows().add("Laptop", 999.99, 5);
    productsTable.getRows().add("Mouse", 29.99, 20);
    productsTable.getRows().add("Keyboard", 79.99, 15);

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument("DataTableTemplate.docx", "DataTableOutput.docx",
        new DataSourceInfo(productsTable, "products"));

    System.out.println("Table generated from DataTable successfully.");
}

DataTable columns are referenced by name rather than through getters, so the template (DataTableTemplate.docx) looks as follows:

Product Name	Price	Quantity
`<<foreach [in products]>><<[Name]>>`	`<<[Price]>>`	`<<[Quantity]>><</foreach>>`

Generate Table with Totals

Add a total row after the data rows:

import com.groupdocs.assembly.*;

public static void generateTableWithTotals() throws Exception
{
    Product[] products =
    {
        new Product("Laptop", 999.99, 5),
        new Product("Mouse", 29.99, 20),
        new Product("Keyboard", 79.99, 15)
    };

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument("TableWithTotalsTemplate.docx", "TableWithTotals.docx",
        new DataSourceInfo(products, "products"));

    System.out.println("Table with totals generated successfully.");
}

Template structure:

Product Name	Price	Quantity
`<<foreach [in products]>><<[getName()]>>`	`<<[getPrice()]:"$#,##0.00">>`	`<<[getQuantity()]>><</foreach>>`
Total	`<<[products.sum(p => p.getPrice())]:"$#,##0.00">>`	`<<[products.sum(p => p.getQuantity())]>>`

Generate Table in Spreadsheet

Tables work similarly in spreadsheet templates:

import com.groupdocs.assembly.*;

public static void generateTableInSpreadsheet() throws Exception
{
    Product[] products =
    {
        new Product("Laptop", 999.99, 5),
        new Product("Mouse", 29.99, 20)
    };

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument("TableTemplate.xlsx", "TableOutput.xlsx",
        new DataSourceInfo(products, "products"));

    System.out.println("Table generated in spreadsheet successfully.");
}

Warning
In spreadsheet templates, the data band is a row of cells: put the opening <<foreach>> tag at the beginning of the first cell of the row and the closing <</foreach>> tag at the end of the last cell of the row. The row is repeated for each item in the collection.

Advanced Usage Topics

To learn more about filtering, sorting, grouping table data, conditional table rows, and advanced table formatting, please refer to the advanced usage section.

More resources

GitHub Examples

You may easily run the code above and see the feature in action in our GitHub examples:

Free Online Apps

Along with the full-featured Java library, we provide simple but powerful free online apps.

To assemble documents from templates and data sources, you can use the online apps from the GroupDocs.Assembly App Product Family.

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