JSON-LD processing

• Expansion
• Compaction

JSON-LD provides a specification, JSON-LD 1.1 Processing Algorithms and API, which provides standard operations for processing JSON-LD. These operations allow JSON data to be transformed to various formats for different purposes, and enables the meaning of data that uses local terminology to be widely comprehended.

The specification describes operations for expansion, compaction, flattening, and converting to or from RDF. This page highlights only the expansion and compaction algorithms; see the specification for information about the other operations.

Expansion

The expansion algorithm removes JSON-LD contexts from a message, cooking any aliases defined in the context directly into the data. In addition, anywhere an array could occur, it places an array. An overview is provided in section 2.1, Expansion.

For example:

{
  "@context": {
    "nc": "http://release.niem.gov/niem/niem-core/4.0/#"
  },
  "nc:PersonPreferredName": "Morty"
}

This data, processed by the expansion algorithm, is expanded to:

[
  {
    "http://release.niem.gov/niem/niem-core/4.0/#PersonPreferredName": [
      {
        "@value": "Morty"
      }
    ]
  }
]

Compaction

The compaction operation is the inverse of the expansion algorithm, encoding JSON-LD data based on a given context. For example, given the expanded data above, compacted against the context:

{
    "nc": "http://release.niem.gov/niem/niem-core/4.0/#"
}

…yields the JSON data:

{
  "@context": {
    "nc": "http://release.niem.gov/niem/niem-core/4.0/#"
  },
  "nc:PersonPreferredName": "Morty"
}

When compacted against an empty context:

{
}

…it yields JSON data that does not depend on any context, but which has a simplified form:

{
  "http://release.niem.gov/niem/niem-core/4.0/#PersonPreferredName": "Morty"
}

The data could be compacted against a context that provides a short local name for the term:

{
  "nick": "http://release.niem.gov/niem/niem-core/4.0/#PersonPreferredName"
}

…yielding compacted data that uses the short term:

{
  "nick": "Morty"
}