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A Concatenation field is computed. It joins the values of other fields on the same record, in the order you list them, separated by a character you choose. The classic use is a campaign name like awareness-us-black_friday, built from a few dropdowns and a text field.

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When to use it

  • Building one canonical string out of several inputs, for example a UTM campaign name from goal, country, and a short label.
  • Producing a deterministic identifier that should always follow the same shape across submissions.
  • Feeding a clean value into a Tagged URL parameter or a Short URL slug.
Don’t use a Concatenation field to attach query parameters to a URL. The output is a plain string and is not URL-aware. Use a Tagged URL field, which handles the base URL and parameter encoding for you.

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How it is configured

A Concatenation field is computed, so it is always required and submitters never type into it. In the field editor you set:
SettingRequiredDefaultWhat it does
partsYesNoneThe ordered list of fields to join. Each part references one other field by its ID. You pick the fields and drag to reorder them. At least one part is required.
separatorNoemptyThe character or string placed between parts, for example -, _, or a space.
remove_extra_separatorsNofalseWhen on, a part whose value is blank is dropped entirely, so you don’t get doubled separators. Cannot be combined with empty_field_replacement.
empty_field_replacementNoNoneA placeholder string used in place of any blank part, which keeps the separator count steady. Only available when remove_extra_separators is off.
uniqueNofalseWhen on, the computed value must be unique across the account’s records.
Each part references another field, not a literal string. Adding the same field twice is prevented, and you cannot add a new part until every existing part has a field selected. When the submission is saved, Terminus reads each referenced field’s current value on that record, applies your empty-value rule, and joins the results with the separator.

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A worked example

In the Campaign URL Builder, a utm_campaign Concatenation field joins a goal dropdown, a country dropdown, and a campaign label into one tracking string. 
type: concatenation
settings:
  parts:
    - { type: field, value: goal }
    - { type: field, value: country }
    - { type: field, value: campaign_label }
  separator: "-"
  remove_extra_separators: true
For a submission where goal is awareness, country is us, and campaign_label is black_friday, the field computes: 
awareness-us-black_friday
If the submitter leaves country blank, remove_extra_separators: true drops that part and the separators around it collapse: 
awareness-black_friday
Without remove_extra_separators, the same blank value would produce awareness--black_friday (two dashes where the country used to be). Switch to empty_field_replacement instead when you want a visible placeholder like na in that gap. The resulting utm_campaign value is then a clean input for the utm_campaign parameter of a Tagged URL field.

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Gotchas

  • You cannot use both empty-value strategies at once. remove_extra_separators and empty_field_replacement are mutually exclusive. The editor hides the replacement input while “Remove extra separators” is on.
  • Parts can only reference other fields. There is no literal-text part. To inject a fixed string, use a Constant field as one of the parts, or put the character in separator (it then appears between every part).
  • The separator is inserted as-is, not URL-encoded. If the output flows into a URL, keep the separator URL-safe (-, _, .) and avoid spaces or &. Encoding only happens later, inside a Tagged URL field.
  • A part that points at a missing or blank field contributes nothing useful. With remove_extra_separators off, a blank part becomes an empty segment; with it on, the part is dropped. Reordering or removing parts only affects records created afterward; existing approved records keep their stored value.