CSV::Table

A CSV::Table instance represents CSV data. (see class CSV).

The instance may have:

• Rows: each is a Table::Row object.

• Headers: names for the columns.

Instance Methods

CSV::Table has three groups of instance methods:

• Its own internally defined instance methods.

• Methods included by module Enumerable.

• Methods delegated to class Array.:

  • Array#empty?

  • Array#length

  • Array#size

Creating a CSV::Table Instance

Commonly, a new CSV::Table instance is created by parsing CSV source using headers:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
table.class # => CSV::Table

You can also create an instance directly. See ::new.

Headers

If a table has headers, the headers serve as labels for the columns of data. Each header serves as the label for its column.

The headers for a CSV::Table object are stored as an Array of Strings.

Commonly, headers are defined in the first row of CSV source:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
table.headers # => ["Name", "Value"]

If no headers are defined, the Array is empty:

table = CSV::Table.new([])
table.headers # => []

Access Modes

CSV::Table provides three modes for accessing table data:

• Row mode.

• Column mode.

• Mixed mode (the default for a new table).

The access mode for aCSV::Table instance affects the behavior of some of its instance methods:

• []

• []=

• delete

• delete_if

• each

• values_at

Row Mode

Set a table to row mode with method by_row!:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
table.by_row! # => #<CSV::Table mode:row row_count:4>

Specify a single row by an Integer index:

# Get a row.
table[1] # => #<CSV::Row "Name":"bar" "Value":"1">
# Set a row, then get it.
table[1] = CSV::Row.new(['Name', 'Value'], ['bam', 3])
table[1] # => #<CSV::Row "Name":"bam" "Value":3>

Specify a sequence of rows by a Range:

# Get rows.
table[1..2] # => [#<CSV::Row "Name":"bam" "Value":3>, #<CSV::Row "Name":"baz" "Value":"2">]
# Set rows, then get them.
table[1..2] = [
  CSV::Row.new(['Name', 'Value'], ['bat', 4]),
  CSV::Row.new(['Name', 'Value'], ['bad', 5]),
]
table[1..2] # => [["Name", #<CSV::Row "Name":"bat" "Value":4>], ["Value", #<CSV::Row "Name":"bad" "Value":5>]]

Column Mode

Set a table to column mode with method by_col!:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
table.by_col! # => #<CSV::Table mode:col row_count:4>

Specify a column by an Integer index:

# Get a column.
table[0]
# Set a column, then get it.
table[0] = ['FOO', 'BAR', 'BAZ']
table[0] # => ["FOO", "BAR", "BAZ"]

Specify a column by its String header:

# Get a column.
table['Name'] # => ["FOO", "BAR", "BAZ"]
# Set a column, then get it.
table['Name'] = ['Foo', 'Bar', 'Baz']
table['Name'] # => ["Foo", "Bar", "Baz"]

Mixed Mode

In mixed mode, you can refer to either rows or columns:

• An Integer index refers to a row.

• A Range index refers to multiple rows.

• A String index refers to a column.

Set a table to mixed mode with method by_col_or_row!:

source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
table = CSV.parse(source, headers: true)
table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4>

Specify a single row by an Integer index:

# Get a row.
table[1] # => #<CSV::Row "Name":"bar" "Value":"1">
# Set a row, then get it.
table[1] = CSV::Row.new(['Name', 'Value'], ['bam', 3])
table[1] # => #<CSV::Row "Name":"bam" "Value":3>

Specify a sequence of rows by a Range:

# Get rows.
table[1..2] # => [#<CSV::Row "Name":"bam" "Value":3>, #<CSV::Row "Name":"baz" "Value":"2">]
# Set rows, then get them.
table[1] = CSV::Row.new(['Name', 'Value'], ['bat', 4])
table[2] = CSV::Row.new(['Name', 'Value'], ['bad', 5])
table[1..2] # => [["Name", #<CSV::Row "Name":"bat" "Value":4>], ["Value", #<CSV::Row "Name":"bad" "Value":5>]]

Specify a column by its String header:

# Get a column.
table['Name'] # => ["foo", "bat", "bad"]
# Set a column, then get it.
table['Name'] = ['Foo', 'Bar', 'Baz']
table['Name'] # => ["Foo", "Bar", "Baz"]

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Response class for Moved Permanently responses (status code 301).

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References:

• Mozilla.

• RFC 9110.

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Response class for Found responses (status code 302).

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References:

• Mozilla.

• RFC 9110.

• Wikipedia.

Response class for Method Not Allowed responses (status code 405).

The request method is not supported for the requested resource.

References:

• Mozilla.

• RFC 9110.

• Wikipedia.

Response class for Not Acceptable responses (status code 406).

The requested resource is capable of generating only content that not acceptable according to the Accept headers sent in the request.

References:

• Mozilla.

• RFC 9110.

• Wikipedia.

Response class for Length Required responses (status code 411).

The request did not specify the length of its content, which is required by the requested resource.

References:

• Mozilla.

• RFC 9110.

• Wikipedia.

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