Destination Properties by Connector¶

Reference for all properties available in the to block when writing to each connector type. Every to block shares a set of universal attributes; the sections below document what target, operation, query, and params mean for each connector.

Universal Attributes¶

Available on every to block regardless of connector type:

Attribute	Type	Default	Description
`connector`	string	required	Target connector name
`target`	string	—	Resource identifier (meaning varies per connector — see below)
`operation`	string	auto	Override operation type (meaning varies per connector)
`format`	string	`json`	Output format: `json`, `xml`
`query`	string	—	Raw SQL with named parameters (`:name`, `:id`) — resolved from transformed payload
`query_filter`	map	—	NoSQL filter document (MongoDB)
`update`	map	—	NoSQL update document (MongoDB `$set`, `$inc`, etc.)
`params`	map	—	Extra connector-specific parameters (CEL expressions)
`when`	string	—	CEL condition — only write if true. Context: `input`, `output`
`parallel`	bool	`true`	In multi-to, run this destination in parallel
`transform`	block	—	Per-destination CEL transform (overrides flow-level transform)

Data mapping¶

to.target        → connector.Data.Target
to.operation     → connector.Data.Operation
to.query         → connector.Data.RawSQL
to.query_filter  → connector.Data.Filters
to.update        → connector.Data.Update
to.params        → connector.Data.Params
transformed data → connector.Data.Payload

Database (SQLite, PostgreSQL, MySQL)¶

Property	Value
`target`	Table name (e.g., `"users"`, `"orders"`)
`operation`	`INSERT` (default for POST), `UPDATE`, `DELETE`
`query`	Raw SQL with named parameters (`:name`, `:email`). Resolved from payload
`params`	Not used (named params come from payload)

Named parameters in `query`¶

When using query, named parameters like :name are replaced with the corresponding field from the transformed payload:

transform {
  number = "input.payload.associateNumber"
  name   = "input.payload.name"
  emails = "input.payload.emails.join(',')"
}

to {
  connector = "magento_db"
  target    = "sales_associate"
  query     = "INSERT INTO sales_associate (number, name, emails) VALUES (:number, :name, :emails) ON DUPLICATE KEY UPDATE name = :name, emails = :emails"
}

Standard operations (no `query`)¶

Without query, the operation is inferred from the HTTP method or set explicitly:

# INSERT — payload fields become columns
to { connector = "db", target = "users" }

# UPDATE — filters from URL params, payload = SET clause
to { connector = "db", target = "users", operation = "UPDATE" }

# DELETE — filters from URL params
to { connector = "db", target = "users", operation = "DELETE" }

PostgreSQL specifics¶

INSERT ... RETURNING * returns the full created row (including id, created_at, etc.)

MongoDB¶

Property	Value
`target`	Collection name (e.g., `"users"`)
`operation`	`INSERT_ONE`, `INSERT_MANY`, `UPDATE_ONE`, `UPDATE_MANY`, `DELETE_ONE`, `DELETE_MANY`, `REPLACE_ONE`
`query_filter`	MongoDB filter document (WHERE equivalent)
`update`	MongoDB update document (`$set`, `$inc`, `$push`, etc.)
`params`	`{ upsert = true }`, `{ documents = [...] }` for INSERT_MANY

to {
  connector    = "mongodb"
  target       = "orders"
  operation    = "UPDATE_ONE"
  query_filter = { order_id = "input.order_id" }
  update       = { "$set" = { status = "completed", updated_at = "now()" } }
}

Message Queues (RabbitMQ, Kafka, Redis Pub/Sub, MQTT)¶

Property	RabbitMQ	Kafka	Redis Pub/Sub	MQTT
`target`	Routing key	Topic	Channel	Topic
`operation`	`PUBLISH` (implicit)	`PUBLISH`	`PUBLISH`	`PUBLISH`
`params`	`{ exchange = "..." }`	—	—	`{ qos = 1, retain = true }`

# RabbitMQ
to {
  connector = "rabbit"
  target    = "order.created"
}

# Kafka
to {
  connector = "kafka"
  target    = "orders"
}

# MQTT with QoS
to {
  connector = "mqtt"
  target    = "sensors/temperature"
  params    = { qos = 1, retain = true }
}

The transformed payload becomes the message body (JSON).

HTTP Client¶

Property	Value
`target`	Endpoint path (e.g., `"/api/users"`, `"POST /api/notify"`)
`operation`	HTTP method override: `GET`, `POST`, `PUT`, `PATCH`, `DELETE`

to {
  connector = "external_api"
  target    = "/webhooks/order-created"
  operation = "POST"
}

The transformed payload becomes the request body. URL parameters from input.params become query string parameters.

GraphQL Client¶

Property	Value
`target`	Full GraphQL query/mutation string
`operation`	Not used (embedded in the query string)

to {
  connector = "graphql_api"
  target    = <<-EOF
    mutation CreateUser($input: UserInput!) {
      createUser(input: $input) { id name email }
    }
  EOF
}

The transformed payload becomes the GraphQL variables.

gRPC Client¶

Property	Value
`target`	RPC method name (e.g., `"CreateUser"`, `"users.UserService/CreateUser"`)
`operation`	Alternative to `target` for the method name

to {
  connector = "grpc_service"
  target    = "CreateUser"
}

The transformed payload becomes the protobuf message fields.

SOAP Client¶

Property	Value
`target`	SOAP operation name (e.g., `"CreateItem"`, `"GetOrder"`)
`operation`	Alternative to `target` for the operation name

to {
  connector = "soap_service"
  target    = "CreateItem"
}

The transformed payload becomes the SOAP body parameters.

File¶

Property	Value
`target`	File path (relative to connector `base_path`)
`operation`	`WRITE` (default), `DELETE`, `COPY`, `MOVE`
`params`	`{ format = "csv" }`, `{ append = true }`, `{ sheet = "Data" }` (Excel)

# Write JSON
to {
  connector = "files"
  target    = "output/report.json"
}

# Append to CSV
to {
  connector = "files"
  target    = "logs/access.csv"
  params    = { format = "csv", append = true }
}

# Write to Excel sheet
to {
  connector = "files"
  target    = "reports/monthly.xlsx"
  params    = { sheet = "March" }
}

Format is auto-detected from file extension. The transformed payload becomes the file content.

S3¶

Property	Value
`target`	S3 object key (e.g., `"uploads/document.pdf"`)
`operation`	`PUT` (default), `DELETE`, `COPY`
`params`	`content`, `content_type`, `storage_class`, `acl`, `metadata`

to {
  connector = "s3"
  target    = "'uploads/' + input.user_id + '/avatar.png'"
  params    = {
    content       = "output._binary"
    content_type  = "'image/png'"
    storage_class = "'STANDARD'"
  }
}

Exec¶

Property	Value
`target`	Command to execute
`operation`	Not used
`params`	`{ args = [...] }`, `{ stdin = "..." }`

to {
  connector = "exec"
  target    = "convert"
  params    = { args = ["-resize", "800x600", "input.file_path", "output.jpg"] }
}

Elasticsearch¶

Property	Value
`target`	Index name (e.g., `"products"`)
`operation`	`index` (default), `update`, `delete`, `bulk`

to {
  connector = "search"
  target    = "products"
  operation = "index"
}

The transformed payload becomes the document to index. Returns _id, status.

PDF¶

Property	Value
`target`	Template path fallback (if not in connector config or payload)
`operation`	`generate` (returns binary for HTTP) or `save` (writes file)

to {
  connector = "invoice_pdf"
  operation = "generate"
}

Template is resolved: payload template field > connector config template > target fallback. All other payload fields become template variables ({{.field_name}}). Special payload fields: filename (for Content-Disposition).

WebSocket¶

Property	Value
`target`	Room name (for `send_to_room`)
`operation`	`broadcast`, `send_to_room`, `send_to_user`

# Broadcast to all clients
to { connector = "ws", operation = "broadcast" }

# Send to specific room
to { connector = "ws", operation = "send_to_room", target = "order-updates" }

# Send to specific user (user_id from payload)
to { connector = "ws", operation = "send_to_user" }

For send_to_user, the payload or filters must include user_id.

SSE (Server-Sent Events)¶

Property	Value
`target`	Room name
`operation`	`broadcast`, `send_to_room`

to { connector = "sse", operation = "send_to_room", target = "dashboard" }

TCP Client¶

Property	Value
`target`	Connection identifier
`operation`	`SEND` (implicit)

The payload is serialized according to the connector's protocol setting (json, msgpack, nestjs).

Notification Connectors¶

Notification connectors receive the transformed payload as the message. The payload fields map to the notification's properties.

Email¶

Payload field	Type	Description
`to`	array	`[{email, name}]` recipients
`subject`	string	Email subject
`text_body`	string	Plain text body
`html_body`	string	HTML body
`template`	string	Override connector-level template path
`template_data`	map	Variables for template rendering
`cc`, `bcc`	array	CC/BCC recipients
`attachments`	array	`[{filename, content, content_type}]`

to { connector = "email_smtp", operation = "send" }

Template resolution: payload template > connector config template.

Slack¶

Payload field	Type	Description
`text`	string	Message text
`channel`	string	Channel name or ID
`blocks`	array	Slack Block Kit blocks
`thread_ts`	string	For threaded replies

Discord¶

Payload field	Type	Description
`content`	string	Message text
`channel_id`	string	Channel ID
`embeds`	array	Discord embed objects

SMS¶

Payload field	Type	Description
`to`	string	Phone number (E.164)
`message`	string	SMS body

Push¶

Payload field	Type	Description
`device_token`	string	Target device
`title`	string	Notification title
`body`	string	Notification body
`data`	map	Custom data payload

Webhook¶

Payload field	Type	Description
`url`	string	Override connector URL
`method`	string	HTTP method
`headers`	map	Extra headers
`body`	any	Request body

Special Response Fields¶

These fields in the flow result have special meaning when returned through the REST connector:

Field	Type	Recognized by	Purpose
`_binary`	string (base64)	REST	Serve as binary download
`_content_type`	string	REST	MIME type for binary response
`_filename`	string	REST	Content-Disposition filename
`http_status_code`	int/string	REST, SOAP	Override HTTP status code
`grpc_status_code`	int/string	gRPC	Override gRPC status code
`_response_headers`	map	REST (aspects)	Extra HTTP response headers

See also: Flows for to block syntax, Configuration Reference for all HCL blocks.