Expands a field with dots into an object field. This processor allows fields with dots in the name to be accessible by other processors in the pipeline. Otherwise these fields can’t be accessed by any processor.

{
  "dot_expander": {
    "field": "foo.bar"
  }
}

For example the dot expand processor would turn this document:

{
  "foo.bar" : "value"
}

into:

{
  "foo" : {
    "bar" : "value"
  }
}

If there is already a bar field nested under foo then this processor merges the foo.bar field into it. If the field is a scalar value then it will turn that field into an array field.

For example, the following document:

{
  "foo.bar" : "value2",
  "foo" : {
    "bar" : "value1"
  }
}

is transformed by the dot_expander processor into:

{
  "foo" : {
    "bar" : ["value1", "value2"]
  }
}

If any field outside of the leaf field conflicts with a pre-existing field of the same name, then that field needs to be renamed first.

Consider the following document:

{
  "foo": "value1",
  "foo.bar": "value2"
}

Then the foo needs to be renamed first before the dot_expander processor is applied. So in order for the foo.bar field to properly be expanded into the bar field under the foo field the following pipeline should be used:

{
  "processors" : [
    {
      "rename" : {
        "field" : "foo",
        "target_field" : "foo.bar""
      }
    },
    {
      "dot_expander": {
        "field": "foo.bar"
      }
    }
  ]
}

The reason for this is that Ingest doesn’t know how to automatically cast a scalar field to an object field.