Reference Adapters Json

Relevant source files

The following files were used as context for generating this wiki page:

• src/convert/adapters/json/Adapter.py
• src/convert/api/init.py
• src/convert/adapters/freecad/Adapter.py
• src/convert/adapters/catia/Adapter.py
• src/convert/adapters/solidworks/core/Adapter.py

JSON & Registry Adapter

The JSON Adapter and the global Adapter Registry provide the primary infrastructure for CAD document conversion within the Kit project. The JSON Adapter enables the serialization and deserialization of the neutral CadDocument model to and from disk, serving as the common interchange format. The Adapter Registry manages the collection of available format-specific adapters, such as those for SOLIDWORKS, CATIA, and FreeCAD, and orchestrates format discovery.

Together, these components allow the system to identify the appropriate adapter for a given source file and perform bidirectional translations through a centralized API. The registry facilitates format-agnostic operations by exposing a unified interface for probing, reading, and writing various CAD formats.

Adapter Architecture

The system uses a modular adapter architecture where each format (JSON, FreeCAD, SOLIDWORKS, CATIA) implements a standard interface. The JsonAdapter composes functionality from metadata, reader, and writer mixins to handle neutral interchange files.

classDiagram
    class JsonAdapter {
        +info: AdapterInfo
        +probe(source) ProbeResult
        +read(source, options) CadDocument
        +write(document, destination, options) WriteResult
    }
    class JsonMetadata {
        +CanSupport(doc, target) bool
    }
    class JsonReader {
        +ReadAction(source, options) CadDocument
    }
    class JsonWriter {
        +EmitTarget(doc, dest, options) WriteResult
    }
    JsonAdapter --|> JsonMetadata
    JsonAdapter --|> JsonReader
    JsonAdapter --|> JsonWriter

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The JsonAdapter acts as the reference implementation for the internal interchange format, allowing other adapters to verify their output by reading or writing neutral JSON models.

The Adapter Registry

The AdapterRegistry maintains the global collection of format-specific adapters. It is initialized via the _build_registry function and exposed through a module-level registry constant. This registry is consumed by the public API to perform operations like convert, open_document, and write_document.

Component Discovery and Registration

The system discovers adapters by querying the registry, which provides metadata such as supported file extensions and capability sets.

Feature	Description
available_adapters	Lists all registered AdapterInfo records.
probe	Determines the format of a source file and the confidence of the match.
read	Converts a source file into a neutral CadDocument.
write	Exports a CadDocument to a specific destination format.

Data Flow: Document Conversion

The following sequence diagram illustrates how the convert API interacts with the registry and specific adapters (e.g., SldprtAdapter for SOLIDWORKS or JsonAdapter) to translate files.

sequenceDiagram
    participant App as "Consumer"
    participant API as "API (ConvertFile)"
    participant Reg as "AdapterRegistry"
    participant SrcAdp as "Source Adapter"
    participant DstAdp as "Destination Adapter"

    App->>API: convert(source, destination)
    API->>Reg: Get adapter for source_format
    Reg-->>API: SrcAdp
    API->>SrcAdp: read(source, options)
    SrcAdp-->>API: CadDocument
    API->>Reg: Get adapter for dest_format
    Reg-->>API: DstAdp
    API->>DstAdp: write(doc, destination, options)
    DstAdp-->>API: WriteResult
    API-->>App: ConversionResult

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The registry ensures that the correct logic is applied for complex formats like SOLIDWORKS (.SLDPRT/.SLDASM) and CATIA (.CATPart/.CATProduct) by evaluating file signatures and extensions.

Format Probing and Confidence

The registry uses format probing to identify unknown files. Each adapter provides a probe method that returns a ProbeResult containing a confidence score.

• High Confidence (1.0): Positive identification via unique magic numbers or required stream structures (e.g., CATIA V5_CFV2 container graph or SOLIDWORKS resolved-feature streams).
• Medium Confidence (0.6 - 0.95): Likely match based on container headers or common file structures.
• Low Confidence (0.0): The file does not match the format's requirements.

Implementation: JSON Adapter Logic

The JsonAdapter is responsible for handling the neutral CadDocument serialization. It validates inputs and outputs to ensure they adhere to the project's interchange schema.

Consult the linked source file for the exact implementation; this reference does not duplicate executable code.

The JSON Adapter allows developers to inspect the results of a conversion by providing a human-readable representation of CAD geometry, assembly structures, and parametric history.