XML

Parse XML documents with automatic schema detection and configurable row element selection.

Usage

loq -i:XML "SELECT * FROM data.xml"

File Format

Basic Structure

<?xml version="1.0" encoding="UTF-8"?>
<users>
  <user>
    <name>Alice</name>
    <age>32</age>
    <city>New York</city>
  </user>
  <user>
    <name>Bob</name>
    <age>28</age>
    <city>San Francisco</city>
  </user>
</users>

With Attributes

<products>
  <product id="1" category="electronics">
    <name>Widget</name>
    <price>9.99</price>
  </product>
  <product id="2" category="clothing">
    <name>T-Shirt</name>
    <price>19.99</price>
  </product>
</products>

Schema Detection

loq automatically:

1. Identifies the row element (e.g., <user>, <product>)
2. Extracts child element text as columns
3. Extracts attributes as columns with @ prefix
4. Infers column types from values

Row Element Detection

loq looks for repeated child elements under the root:

<root>
  <item>...</item>  <!-- Row element: item -->
  <item>...</item>
  <item>...</item>
</root>

Column Mapping

XML Element	Column Name	Example Value
<name>Alice</name>	name	Alice
<user id="1">	@id	1
<address><city>NY</city></address>	address.city	NY

Options

Custom Row Element

Specify which element represents a row:

loq -i:XML -iRowElement:record "SELECT * FROM data.xml"

Example

<data>
  <metadata>
    <version>1.0</version>
  </metadata>
  <records>
    <record>
      <name>Alice</name>
    </record>
    <record>
      <name>Bob</name>
    </record>
  </records>
</data>

loq -i:XML -iRowElement:record "SELECT * FROM data.xml"

Examples

Basic Query

loq -i:XML "SELECT * FROM users.xml"

Select Specific Columns

loq -i:XML "SELECT name, age FROM users.xml WHERE age > 30"

Query Attributes

loq -i:XML "SELECT \"@id\", name, \"@category\" FROM products.xml"

TIP

Attribute columns (prefixed with @) should be quoted.

Nested Elements

For nested structure:

<users>
  <user>
    <name>Alice</name>
    <address>
      <city>New York</city>
      <zip>10001</zip>
    </address>
  </user>
</users>

loq -i:XML "SELECT name, \"address.city\", \"address.zip\" FROM users.xml"

Aggregation

loq -i:XML "SELECT \"@category\", COUNT(*), AVG(price)
                  FROM products.xml
                  GROUP BY \"@category\""

Filtering

loq -i:XML "SELECT * FROM orders.xml
                  WHERE \"@status\" = 'pending'
                  AND total > 100"

Type Inference

Values are automatically typed:

XML Value	Detected Type
<age>32</age>	Integer
<price>9.99</price>	Float
<active>true</active>	Boolean
<name>Alice</name>	String
<note/> (empty)	Null

Common Patterns

Configuration Files

<config>
  <database>
    <host>localhost</host>
    <port>5432</port>
    <name>myapp</name>
  </database>
  <cache>
    <enabled>true</enabled>
    <ttl>3600</ttl>
  </cache>
</config>

loq -i:XML "SELECT \"database.host\", \"database.port\"
                  FROM config.xml"

RSS/Atom Feeds

loq -i:XML -iRowElement:item "SELECT title, link, pubDate
                                    FROM feed.xml
                                    ORDER BY pubDate DESC
                                    LIMIT 10"

SOAP Responses

loq -i:XML -iRowElement:Result "SELECT * FROM response.xml"

SVG/HTML

# Extract all elements
loq -i:XML -iRowElement:rect "SELECT \"@x\", \"@y\", \"@width\", \"@height\"
                                    FROM drawing.svg"

Mixed Content

Elements with mixed content (text and child elements) extract text content:

<message>
  Hello <b>World</b>!
</message>

The message column contains: Hello ! (child element text is excluded)

Namespaces

XML namespaces are handled transparently:

<root xmlns="http://example.com/ns">
  <item>
    <name>Alice</name>
  </item>
</root>

Column names don't include namespace prefixes.

Performance Tips

Large XML Files

# Use LIMIT during exploration
loq -i:XML "SELECT * FROM large.xml LIMIT 100"

# Filter early
loq -i:XML "SELECT * FROM large.xml WHERE status = 'active'"

Streaming

Large XML files are parsed in a streaming manner when possible, reducing memory usage.

Troubleshooting

Row Element Not Detected

If rows aren't detected correctly:

# Specify the row element explicitly
loq -i:XML -iRowElement:item "SELECT * FROM data.xml"

Column Names With Special Characters

Quote column names with @, ., or special characters:

SELECT "@id", "user.name" FROM data.xml

Encoding Issues

Ensure XML declares encoding:

<?xml version="1.0" encoding="UTF-8"?>

Invalid XML

loq -i:XML "SELECT * FROM data.xml"
# Error: Invalid XML at line 42

Validate XML with online tools or xmllint:

xmllint --noout data.xml

See Also

• Input Formats Overview
• JSON Format
• XML Output