DSL Reference

Complete reference for the DSL (Domain Specific Language) for business rules in Fyso.

General Structure

{
  "type": "compute | validate | action",
  "triggers": ["campo1", "campo2"],
  "triggerType": "field_change | before_save | after_save | on_load",
  "compute": { ... },
  "validate": [ ... ],
  "transform": { ... },
  "actions": [ ... ]
}

Compute

Calculates values automatically. Supports several formats:

Simple Formula (shorthand)

{
  "compute": {
    "total": "cantidad * precio"
  }
}

The shorthand is internally normalized to:

{
  "compute": {
    "total": { "type": "formula", "expression": "cantidad * precio" }
  }
}

Explicit Formula

{
  "compute": {
    "iva": { "type": "formula", "expression": "subtotal * 0.21" },
    "total": { "type": "formula", "expression": "subtotal + iva" }
  }
}

Conditional

Calculates a value based on conditions:

{
  "compute": {
    "descuento": {
      "type": "conditional",
      "conditions": [
        { "when": "cantidad >= 100", "then": "0.15" },
        { "when": "cantidad >= 50", "then": "0.10" },
        { "when": "cantidad >= 10", "then": "0.05" }
      ],
      "default": "0"
    }
  }
}

Lookup

Looks up a value in another entity:

{
  "compute": {
    "precio_unitario": {
      "type": "lookup",
      "entity": "productos",
      "matchField": "id",
      "matchValue": "producto_id",
      "resultField": "precio"
    }
  }
}

Property	Type	Description
`entity`	string	Entity to search in
`matchField`	string	Field in the target entity to match against
`matchValue`	string	Field in the current record containing the value to search for
`resultField`	string	Field in the target entity whose value to return

Aggregate

Aggregates values from multiple records of another entity:

{
  "compute": {
    "total_lineas": {
      "type": "aggregate",
      "entity": "lineas_factura",
      "aggregateOp": "sum",
      "aggregateField": "subtotal",
      "filter": { "factura_id": "id" }
    },
    "cantidad_items": {
      "type": "aggregate",
      "entity": "lineas_factura",
      "aggregateOp": "count",
      "filter": { "factura_id": "id" }
    }
  }
}

Property	Type	Description
`entity`	string	Entity to aggregate
`aggregateOp`	string	Operation: `"sum"` or `"count"`
`aggregateField`	string	Field to sum (required for `sum`)
`filter`	object	Filter: `{ target_field: "current_field" }`

Validate

Array of validation rules:

{
  "validate": [
    {
      "id": "precio_positivo",
      "condition": "precio > 0",
      "message": "El precio debe ser mayor a cero",
      "severity": "error",
      "field": "precio"
    }
  ]
}

Property	Type	Required	Description
`id`	string	Yes	Unique identifier for the validation
`condition`	string	Yes	Boolean expression that must be true
`message`	string	Yes	Error message if the condition is false
`severity`	string	Yes	`"error"` (blocks save), `"warning"`, `"info"`
`field`	string	No	Field to associate the error with in the UI

Transform

Transforms field values:

{
  "transform": {
    "nombre": { "type": "uppercase" },
    "email": { "type": "lowercase" },
    "descripcion": { "type": "trim" },
    "precio": { "type": "round", "decimals": 2 }
  }
}

Type	Description
`uppercase`	Converts to uppercase
`lowercase`	Converts to lowercase
`trim`	Removes leading and trailing whitespace
`round`	Rounds to N decimal places

Actions

Side effects that execute after saving. Actions run sequentially and can share data through the execution context.

`update_related`

Updates a record in a different entity:

{
  "actions": [
    {
      "type": "update_related",
      "entity": "pedidos",
      "recordId": "pedido_id",
      "data": {
        "total": {
          "type": "aggregate",
          "entity": "lineas",
          "aggregateOp": "sum",
          "aggregateField": "subtotal",
          "filter": { "pedido_id": "pedido_id" }
        }
      }
    }
  ]
}

`update_record`

Updates fields on the current record. Unlike update_related, this does not require entity or recordId — it targets the record that triggered the rule.

{
  "type": "update_record",
  "fields": {
    "estado": "aprobado",
    "aprobado_por": "$ctx.approver_name"
  }
}

Property	Type	Required	Description
`fields`	object	Yes	Field→value pairs to set on the current record

Values can reference execution context variables using $ctx.* syntax. This is useful for chaining actions — for example, storing an AI classification result and then writing it back to the record.

`ai_call`

Invokes an AI model as a rule action. Useful for classification, extraction, summarization, or any text generation task triggered by record changes.

{
  "type": "ai_call",
  "prompt": "Classify this support ticket: {{descripcion}}",
  "system_prompt": "You are a ticket classifier. Respond with exactly one of: bug, feature, question",
  "model": "gpt-4o-mini",
  "temperature": 0.3,
  "max_tokens": 100,
  "store_result_as": "$ctx.classification"
}

Property	Type	Required	Description
`prompt`	string	Yes (unless `prompt_template`)	The prompt to send. Supports `{{field}}` substitution from the current record.
`prompt_template`	string	No	Slug of a reusable prompt template (resolves from `_fyso_ai_templates`)
`system_prompt`	string	No	System prompt for the AI call
`system_prompt_template`	string	No	Slug of a system prompt template
`model`	string	No	Override model. Uses the tenant default if omitted.
`temperature`	number	No	0–2. Uses the provider default if omitted.
`max_tokens`	number	No	1–32000
`store_result_as`	string	No	Store the AI response in execution context. Must follow the format `$ctx.<identifier>`.

Guardrails:

A budget check runs before every AI call. If the tenant has exhausted its AI budget, the call is skipped.
A rate limit check runs before the budget check.
Failures are captured as error validations — the pipeline continues with remaining actions.
All calls are logged to _fyso_ai_call_logs.

`webhook_send`

Sends an HTTP POST request to an external URL. Useful for notifications, integrations, and event forwarding.

{
  "type": "webhook_send",
  "url": "https://hooks.example.com/notify",
  "headers": {
    "X-Api-Key": "my-token"
  },
  "payload": {
    "ticket_id": "id",
    "status": "estado",
    "customer": "nombre_cliente"
  },
  "timeoutMs": 5000
}

Property	Type	Required	Description
`url`	string	Yes	Destination URL. Supports `{{field}}` templates. SSRF protection enforced.
`headers`	object	No	Custom HTTP headers. Supports `{{field}}` templates.
`payload`	object	No	Key→value payload. Values resolve from the current record at fire time. `_record_id` is injected automatically.
`timeoutMs`	number	No	100–30000 ms (default: 5000)

Behavior:

Always sends a POST request with a JSON body.
1 automatic retry on failure (fire-and-forget — does not block the rule pipeline).
SSRF filter blocks private/internal IPs both at rule save time and at execution time.

Execution Context

Business rules can share data between actions using the execution context ($ctx). This is how you chain actions together — for example, calling an AI model and then writing the result back to the record.

The flow:

An ai_call action stores its result via store_result_as: "$ctx.classification".
A subsequent update_record action references $ctx.classification in its fields.

{
  "actions": [
    {
      "type": "ai_call",
      "prompt": "Classify: {{descripcion}}",
      "system_prompt": "Respond with one of: bug, feature, question",
      "store_result_as": "$ctx.classification"
    },
    {
      "type": "update_record",
      "fields": {
        "categoria": "$ctx.classification"
      }
    }
  ]
}

Context variables are scoped to a single rule execution. They do not persist across separate rule triggers.

Optimistic Locking

All records include a _record_version field in API responses. When you update a record via the API and include _record_version in the payload, the server checks that the version matches the stored value. If it doesn't match (another update happened in between), the request is rejected with a version conflict error.

Actions triggered by business rules (update_related, update_record) bypass the version check to avoid conflicts during automated processing.

Allowed Operators

Category	Operators
Arithmetic	`+`, `-`, `*`, `/`
Comparison	`>`, `<`, `>=`, `<=`, `==`, `!=`
Logical	`and`, `or`

Allowed Functions

Function	Description	Example
`round(x, n)`	Rounds to n decimal places	`round(total, 2)`
`coalesce(a, b)`	First non-null value	`coalesce(descuento, 0)`
`abs(x)`	Absolute value	`abs(diferencia)`
`min(a, b)`	Minimum	`min(stock, pedido)`
`max(a, b)`	Maximum	`max(precio, precio_minimo)`
`floor(x)`	Round down	`floor(cantidad)`
`ceil(x)`	Round up	`ceil(horas)`
`len(s)`	String length	`len(nombre)`
`upper(s)`	Uppercase	`upper(codigo)`
`lower(s)`	Lowercase	`lower(email)`
`trim(s)`	Remove whitespace	`trim(nombre)`
`now()`	Current date and time	`now()`
`today()`	Current date	`today()`

General Structure​

Compute​

Simple Formula (shorthand)​

Explicit Formula​

Conditional​

Lookup​

Aggregate​

Validate​

Transform​

Actions​

update_related​

update_record​

ai_call​

webhook_send​

Execution Context​

Optimistic Locking​

Allowed Operators​

Allowed Functions​