imtdb::IJsonBasedMetaInfoDelegate

Converts document metadata to/from JSON representation. More...

#include <IJsonBasedMetaInfoDelegate.h>

Inherits istd::IPolymorphic.

Inherited by imtdbgql::TSdlBasedMetaInfoDelegate< sdl::controlsgallery::ContactInfos::CContactInfoItemData::V1_0 > [virtual], imtdb::CJsonBasedMetaInfoDelegateComp [virtual], and imtdbgql::TSdlBasedMetaInfoDelegate< MetaInfoRepresentation > [virtual].

Public Member Functions
virtual bool	ToJsonRepresentation (const idoc::IDocumentMetaInfo &metaInfo, QByteArray &json, const QByteArray &typeId) const =0
	Converts metadata to JSON representation.
virtual bool	FromJsonRepresentation (const QByteArray &json, idoc::IDocumentMetaInfo &metaInfo, const QByteArray &typeId) const =0
	Creates metadata from JSON representation.

Detailed Description

Converts document metadata to/from JSON representation.

IJsonBasedMetaInfoDelegate provides bidirectional conversion between structured metadata (IDocumentMetaInfo) and JSON format for database storage. This enables rich, schema-less metadata to be persisted in JSON/JSONB database columns.

Purpose

Metadata in imtdb applications includes:

• Custom fields and attributes
• Tags and categories
• References to dependent objects
• Revision information
• User-defined key-value pairs

This interface standardizes the JSON schema for metadata storage, ensuring consistency across different components and enabling JSON-based queries.

JSON Schema

Typical metadata JSON structure:

{
  "customFields": {
    "priority": "high",
    "category": "bug-fix"
  },
  "tags": ["urgent", "security"],
  "dependentRefs": {
    "parentIssue": "issue-123",
    "relatedUsers": ["user-1", "user-2"]
  },
  "revisionInfo": {
    "revisionNumber": 5,
    "lastModifiedBy": "user-admin",
    "timestamp": "2024-01-15T10:30:00Z"
  }
}

Implementations

• CJsonBasedMetaInfoDelegateComp: Abstract base with common logic
• Subclasses implement specific JSON schema variations

Usage Example

auto delegate = acf::CreateComponent<CJsonBasedMetaInfoDelegateComp>();
 
// Serialize metadata to JSON for database storage
auto metaInfo = acf::CreateComponent<CDocumentMetaInfoComp>();
metaInfo->SetValue("priority", "high");
metaInfo->SetValue("category", "bug-fix");
 
QByteArray typeId = "MyDocumentType";
QByteArray json;
if (delegate->ToJsonRepresentation(*metaInfo, json, typeId)) {
    // Store json in database JSONB column
}
 
// Deserialize metadata from database
QByteArray storedJson = ...; // from database
auto loadedMetaInfo = acf::CreateComponent<CDocumentMetaInfoComp>();
if (delegate->FromJsonRepresentation(storedJson, *loadedMetaInfo, typeId)) {
    QString priority = loadedMetaInfo->GetValue("priority").toString();
}

Note

The JSON schema is versioned to support migrations

Implementations must handle forward/backward compatibility

See also

CJsonBasedMetaInfoDelegateComp for base implementation

idoc::IDocumentMetaInfo for the metadata interface

Definition at line 89 of file IJsonBasedMetaInfoDelegate.h.

Member Function Documentation

FromJsonRepresentation()

virtual bool imtdb::IJsonBasedMetaInfoDelegate::FromJsonRepresentation ( const QByteArray &  json, idoc::IDocumentMetaInfo &  metaInfo, const QByteArray &  typeId  ) const

pure virtual

Creates metadata from JSON representation.

Deserializes a JSON byte array into an IDocumentMetaInfo object, parsing the JSON according to the delegate's schema and populating the metadata with fields and values.

Parameters

	json	The JSON byte array to parse (UTF-8 encoded)
[out]	metaInfo	Receives the deserialized metadata
	typeId	The type identifier of the document being deserialized

Returns

true if parsing and population succeeded, false on error

Note

Invalid JSON returns false and leaves metaInfo unchanged

Missing fields in JSON result in absent fields in metaInfo

Extra fields in JSON may be ignored or cause errors depending on implementation

The typeId parameter allows type-specific deserialization logic

Example:

QByteArray json = R"({"status":"active","priority":10})";
auto metaInfo = acf::CreateComponent<CDocumentMetaInfoComp>();
QByteArray typeId = "MyDocumentType";
 
if (delegate->FromJsonRepresentation(json, *metaInfo, typeId)) {
    QString status = metaInfo->GetValue("status").toString();     // "active"
    int priority = metaInfo->GetValue("priority").toInt();        // 10
}

See also

ToJsonRepresentation()

ToJsonRepresentation()

virtual bool imtdb::IJsonBasedMetaInfoDelegate::ToJsonRepresentation ( const idoc::IDocumentMetaInfo &  metaInfo, QByteArray &  json, const QByteArray &  typeId  ) const

pure virtual

Converts metadata to JSON representation.

Serializes an IDocumentMetaInfo object to a JSON byte array following the delegate's JSON schema. The resulting JSON can be stored in database JSONB/JSON columns.

Parameters

	metaInfo	The metadata object to serialize
[out]	json	Receives the JSON representation (UTF-8 encoded)
	typeId	The type identifier of the document being serialized

Returns

true if serialization succeeded, false on error

Note

The JSON is compact (no formatting) for efficient storage

NULL or empty metadata may produce empty JSON object "{}"

The typeId parameter allows type-specific serialization logic

Example:

auto metaInfo = acf::CreateComponent<CDocumentMetaInfoComp>();
metaInfo->SetValue("status", "active");
metaInfo->SetValue("tags", QStringList{"important", "reviewed"});
 
QByteArray json;
QByteArray typeId = "MyDocumentType";
delegate->ToJsonRepresentation(*metaInfo, json, typeId);
// json contains: {"status":"active","tags":["important","reviewed"]}

See also

FromJsonRepresentation()