Struct SourceMappingEngine 

pub struct SourceMappingEngine { /* private fields */ }

Source mapping engine that transforms payloads into graph change events.

Uses Handlebars templates to extract element IDs, labels, properties, and operations from arbitrary JSON contexts.

The context is a serde_json::Value that each source builds with its own variables. For example:

• HTTP source: { "payload": ..., "headers": ..., "route": ..., "query": ... }
• Kafka source: { "payload": ..., "key": ..., "topic": ..., "partition": ..., "offset": ... }

Implementations

impl SourceMappingEngine

pub fn new() -> Self

Create a new mapping engine with custom helpers registered

pub fn render_string( &self, template: &str, context: &JsonValue, ) -> Result<String>

Render a template string with the given context

pub fn render_value( &self, template: &str, context: &JsonValue, ) -> Result<JsonValue>

Render a template and preserve the JSON value type

If the template is a simple variable reference like {{payload.field}}, this returns the original JSON value. Otherwise, it returns the rendered string.

pub fn process_mapping( &self, mapping: &SourceMapping, context: &JsonValue, source_id: &str, ) -> Result<SourceChange>

Process a source mapping and create a SourceChange.

The context should be a JSON object containing all variables available to templates (e.g., payload, key, topic, headers, etc.).

pub fn condition_matches( &self, condition: &MappingCondition, context: &JsonValue, headers: Option<&HashMap<String, String>>, ) -> bool

Check if a mapping condition matches the given context.

The headers parameter is optional and only used for header-based conditions.

pub fn find_matching_mapping<'a>( &self, mappings: &'a [SourceMapping], context: &JsonValue, headers: Option<&HashMap<String, String>>, ) -> Option<&'a SourceMapping>

Find the first matching mapping from a list based on conditions.

Returns None if no mapping matches.

Trait Implementations

impl Default for SourceMappingEngine

fn default() -> Self

Returns the “default value” for a type.