bmel:get-json-field¶

Category: JSON · Returns: bmel:any

bmel:get-json-field(object: bmel:any, field: bmel:json-field)

Description¶

Returns the value of one top-level field of a JSON object. The field is written with the #{FIELD_NAME} notation — the attribute reference operator (see Resource and field references operators).

When the object comes from bmel:get-resource-by-id, the BMEL editor knows its resource type: typing #{ lists that resource type's imported columns, the field name is validated against them, and the result takes the column's type — so a numeric column such as input_cost_per_token can be used directly in arithmetic. Returns null when the object is null or has no such field.

Arguments¶

Parameter	Type	Required	Description
`object`	`bmel:any`		The JSON object to read from — typically the result of `bmel:get-resource-by-id`.
`field`	`bmel:json-field`		The field to return, as `#{FIELD_NAME}` (e.g. `#{input_cost_per_token}`).

Example¶

Cost of an invocation: input and output tokens, each times the model's price per token.

{invokeAgent:Response Payload}.$.usage.prompt_tokens *
    bmel:get-json-field(bmel:get-resource-by-id(#{aimodel}, {invokeAgent:Request Payload}.$.model),
        #{input_cost_per_token})
+ {invokeAgent:Response Payload}.$.usage.completion_tokens *
    bmel:get-json-field(bmel:get-resource-by-id(#{aimodel}, {invokeAgent:Request Payload}.$.model),
        #{output_cost_per_token})

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Template dependency changes¶

Resource-type and attribute references written with #{Name} participate in mapping dependency validation, including nested calls. Removing or redefining a referenced dependency can invalidate the enclosing expression and trigger IntelliSense revalidation during editing or a Published-version fork. See ASBO dependencies in BMEL.