`json-template` (Transform Node)

The JSON Template node takes a single JSON input and an object-shaped template. Each string value in the template is treated as a JMESPath expression and evaluated against the input; the results are combined into a new JSON object. Non-string values (numbers, booleans, null, nested objects and arrays) are copied as-is.

Use this node to reshape or extract data from upstream JSON (e.g. from a previous transform or from a dashboard payload) into a structure required by a downstream node or dashboard.

Configuration Schema

Property	Type	Required	Description
`template`	`object`	Yes	Object tree whose string leaves are JMESPath expressions. Nested objects and arrays are allowed; only string values are evaluated as expressions.
`strict`	`boolean`	No	If `true`, the node fails when any JMESPath expression errors. If `false`, failing expressions yield `null` and the node continues. Defaults to `true`.

How it works

The node parses the upstream payload as JSON.
It walks the template recursively. For every string value it finds, it compiles and runs that string as a JMESPath expression against the input JSON and replaces the string with the result.
For object and array values in the template, it recurses and applies the same rule to their children.
For numbers, booleans, and null in the template, it copies them unchanged to the output.

To output a literal string in the template, use JMESPath string literal syntax: "'Your literal string'".

Example

Input JSON:


{
  "tables": {
    "with_timestamps": {
      "rows": [
        { "captured_at": "2025-01-01T00:00:00Z", "speed": "10" },
        { "captured_at": "2025-01-01T00:00:01Z", "speed": "12" }
      ]
    }
  }
}

Template:


{
  "template": {
    "chartTitle": "'Timeline'",
    "points": "tables.with_timestamps.rows[].{Data: speed, DateTime: captured_at}"
  },
  "strict": true
}

Output:


{
  "chartTitle": "Timeline",
  "points": [
    {"Data": "10", "DateTime": "2025-01-01T00:00:00Z"},
    {"Data": "12", "DateTime": "2025-01-01T00:00:01Z"}
  ]
}

Example configuration


{
  "template": {
    "summary": "stats.summary",
    "count": "length(items)",
    "firstItem": "items[0]"
  },
  "strict": true
}

Integration in a session template

Place a json-template node after any node that emits JSON (e.g. tabular-query, json-filter, or another transform).
Define the template object so that string leaves are JMESPath expressions over that input.
Set strict to true to fail on expression errors, or false to substitute null and continue.
Connect downstream nodes to consume the rendered JSON.

Core Utils Runner
Node Templates
JSON Flatten Node (to flatten the result to CSV/TSV)

json-template (Transform Node)