Data and expressions

In any field that takes a value, «Insert variable» opens a picker with the variables available at that step. A variable belongs to a group:

• You drill down into structures: Order > Contact's email. The picker shows the path as a breadcrumb.
• The picker only offers variables whose type fits the field. A variable of the type Unknown fits no typed field.
• A step sees the system variables, the trigger, the steps before it at the same level and the steps of the levels above it.
• Because the key is the step's id, renaming a Set variable step does not break anything, and deleting a step breaks every reference to it. A broken reference is painted red in the editor and blocks switching the workflow live. The server does not check references when you save.
• The editor does not offer values created inside a branch or a loop after it ends, even though they do exist at run time if that branch ran. Compute the value before the composite step if you need it after.
• A «Try» step publishes only its outcome, as «Try result»: «Has failed» (true or false) and «Error message» (text, empty when nothing failed). What the steps inside it created never comes out, because after a failure some of it may not exist. See the Try step.

A value has a type. The editor knows the type of every variable it offers. You declare types yourself in five places: the body of a webhook, the response of an HTTP request, the data of a signal, and the form of a manual trigger and of a "from another workflow" trigger. The types reference lists the eleven kinds with their operators (text, number, true/false, date, enumeration, record, structure, list, tuple, file and unknown). What each one does when the run checks data against it:

• A number is a JSON number: the text "42" is not one. True/false is strict.
• A date is a day or an instant. You must say which when you declare it; both are accepted at run time, and a declared date defaults to an instant.
• An enumeration holds the option's value, not its label.
• A structure has named fields and every declared field is required; extra fields are ignored. In a list every item is checked; in a tuple only the declared positions are.
• A text can say it is the id of a kind of record; that only helps the picker.
• A file is produced by a step and cannot be written by hand.
• Unknown accepts anything, including a missing or null value, and a variable of that type fits no typed field of the picker.

When the data does not match its declared type, the step (or the trigger) fails with the path of the first fields that do not match, for example customer.email: expected a text and received a number. A webhook body is validated after Filmo has answered; see the page on incoming webhooks.

Functions are available in the «Set variable» step. Choose «Function» as the kind of value, pick the function and fill in its arguments, which can be functions themselves. Use the result afterwards as a variable. The data of a Fire a signal step also accepts functions.

The functions come in eight groups: arithmetic, boolean, comparison, text, date, lists, conditional and objects. The functions reference lists each one with its arguments and where it can be used.

Three examples from the engine's own checks:

• Format date uses date-fns letters, such as dd/MM/yyyy (not DD/MM/YYYY, which is refused); the month and day names it writes are always in Spanish, whatever language the app is in.
• Starts with, Ends with and Contains are case-sensitive and only accept text. An empty text to look for always matches.
• Arithmetic uses ordinary floating-point numbers, with their usual rounding artifacts. There is no currency type and no number-formatting function. For exact money totals use the Aggregate values step, which sums exactly.
• There is no default-value ("coalesce") function. You can build one with Condition (if, then, else).

How an empty or missing value behaves depends on where it is used. These rules decide most of the failures you will see.

• system_today is a date without a time, in the company's time zone. Trigger dates, such as trigger_createdAt and trigger_scheduledAt, are instants in UTC. Compare like with like.
• Add days, Days between and Format date keep the precision of what you give them: a date gives a date, an instant gives an instant. A date with an impossible day, or an instant without a zone, produces no value.
• Operations on instants may use the time zone of the server rather than the company's. Prefer dates without a time, which are exact, when the day matters.
• Change the company's time zone in «Date and formats» («Company time zone») in the business settings.

• Saving checks the shape of the workflow only: that each field holds a kind of value it accepts, and that the definition is not more than 100 levels deep. A failed check is a 422 that names the path and the first three problems.
• Blank required fields are allowed in a draft. They stop you switching the workflow live.
• Whether a variable exists, whether a function's arguments make sense and whether a value has a value at run time are not checked on the server.