Working with CSV Data Sources Leave feedback

To access CSV data while building a report, pass a CsvDataSource instance to the assembler as a data source. Using CsvDataSource enables you to work with typed values rather than just strings in template documents. Although CSV as a format does not define a way to store values of types other than strings, CsvDataSource recognizes values of the following types by their string representations:

• Integer
• Long
• Double
• Boolean
• Date

Warning

For recognition of data types to work, string representations of corresponding values must be formed using invariant culture settings.

In template documents, a CsvDataSource instance should be treated in the same way as if it was a DataTable instance (see “Using Data Sources” for more information) as shown in the following example.

Suppose we have CSV data like:

John Doe,30,1989-04-01 4:00:00 pm
Jane Doe,27,1992-01-31 07:00:00 am
John Smith,51,1968-03-08 1:00:00 pm

And the following template:

<<foreach [in persons]>>Name: <<[Column1]>>, Age: <<[Column2]>>, Date of Birth: <<[Column3]:"dd.MM.yyyy">>
<</foreach>>
Average age: <<[persons.average(p => p.Column2)]>>

The code looks like this:

const groupdocs = require('@groupdocs/groupdocs.assembly');

const dataSource = new groupdocs.CsvDataSource("persons.csv");
const assembler = new groupdocs.DocumentAssembler();
assembler.assembleDocument("template.txt", "report.txt",
    new groupdocs.DataSourceInfo(dataSource, "persons"));

The result is:

Name: John Doe, Age: 30, Date of Birth: 01.04.1989
Name: Jane Doe, Age: 27, Date of Birth: 31.01.1992
Name: John Smith, Age: 51, Date of Birth: 08.03.1968

Average age: 36.0

Warning

Using a custom date-time format and an extension method involving arithmetic in the template is possible because text values of Column3 and Column2 are automatically converted to a date and an integer respectively.

By default, CsvDataSource uses column names such as “Column1”, “Column2”, and so on, as you can see from the previous example. However, CsvDataSource can be configured to read column names from the first line of CSV data as shown in the following example.

Suppose we have CSV data like:

Name,Age,Birth
John Doe,30,1989-04-01 4:00:00 pm
Jane Doe,27,1992-01-31 07:00:00 am
John Smith,51,1968-03-08 1:00:00 pm

And the following template:

<<foreach [in persons]>>Name: <<[Name]>>, Age: <<[Age]>>, Date of Birth: <<[Birth]:"dd.MM.yyyy">>
<</foreach>>
Average age: <<[persons.average(p => p.Age)]>>

Pass true to the CsvDataLoadOptions constructor to read column names from the first line:

const groupdocs = require('@groupdocs/groupdocs.assembly');

// Source template and destination report
const templatePath = "CsvDatasetDemo.txt";
const reportPath = "SimpleCsvDSDemo Out.txt";

// Read column names from the first line of CSV data
const options = new groupdocs.CsvDataLoadOptions(true);
const dataSource = new groupdocs.CsvDataSource("persons-with-headers.csv", options);
const dataSourceInfo = new groupdocs.DataSourceInfo(dataSource, "persons");

// Assemble the document
const assembler = new groupdocs.DocumentAssembler();
assembler.assembleDocument(templatePath, reportPath, dataSourceInfo);

process.exit(0);

The result is:

Name: John Doe, Age: 30, Date of Birth: 01.04.1989
Name: Jane Doe, Age: 27, Date of Birth: 31.01.1992
Name: John Smith, Age: 51, Date of Birth: 08.03.1968

Average age: 36.0

You can also use CsvDataLoadOptions to customize the following characters playing special roles while loading CSV data:

• Value separator (the default is comma), set with setDelimiter
• Single-line comment start (the default is sharp), set with setCommentChar
• Quotation mark enabling to use other special characters within a value (the default is double quotes), set with setQuoteChar

These setters take a Java char. Create one from a JavaScript string with java.newChar:

const java = require('java');

const options = new groupdocs.CsvDataLoadOptions();
options.hasHeaders(true);
options.setDelimiter(java.newChar(';'));
options.setCommentChar(java.newChar('/'));
options.setQuoteChar(java.newChar('"'));

const dataSource = new groupdocs.CsvDataSource("persons.csv", options);

Note

Passing a JavaScript string directly (for example, options.setDelimiter(';')) fails with the error Could not find method "setDelimiter(java.lang.String)".

The sample file below has the same columns; its dates are written as M/d/yyyy H:mm, so how they are recognized depends on the current culture.

• Person.csv

• CsvDatasetDemo.txt