The filters block

The filters block contains information on how the layer is being filtered before displaying. In order for a feature to be shown on the map it must evaluate the filter expression to true.

Filters are written using a JSON infix notation that looks like one of [identifier, operator, operand], true or false .

• Valid identifiers are either a feature property or a nested expression.

• Valid operators are:

  • "lt" – Less than

  • "gt" – Greater than

  • "le" – Less than or equal to

  • "ge" – Greater than or equal to

  • "eq" – Equal to

  • "ne" – Not equal to

  • "and" – And, cast to boolean

  • "or" – Or, cast to boolean

  • "cn" – Contains the operand, cast to string

  • "nc" – Does not contain the operand, cast to string

  • "in" – Contained in the operand list

  • "ni" – Not contained in the operand list

  • "is" – Used to match against null values

  • "isnt" – Used to match against null values

• Operands are:

  • A numerical value, a string value, a boolean value

  • An array of numerical, string, or boolean values, a shorthand expanded to these patterns:

    • Input 1: [id, "in", [element1, …, elementN]]

    • Expansion 1: id is equal ("eq") to one or more of the elements

    • Input 2: [id, "ni", [element1, …, elementN]]

    • Expansion 2: id is not equal ("ne") to any of the elements

    • Not defined for operators other than "in" and "ni"

  • A nested expression

• In cases of type mismatch cast the identifier value to the operand’s type

  • Type casting applies element-wise to lists with "in" and "ni" operators

Example of a filter block that filters out features with a value less than 50000 on the acres property

"filters": ["acres", "lt", 50000]

Example of a more complex filter block

"filters": [["acres", "ge", 50000], "and", ["acres", "le", 70000]]

Behavior notes

• Case & diacritics: eq, ne, gt, ge, lt, le, cn, and nc compare strings case-insensitively and diacritic-insensitively. ["status", "eq", "active"] matches "Active" and "ACTIVE".

• in / ni are case-sensitive, unlike the operators above, and do per-element type coercion (["id", "in", [5]] matches a string "5"). in with an empty array always returns false; ni with an empty array always returns true.

• Null handling: use is / isnt only for null/existence checks (with null as the value) — not for value equality. Most other operators yield null (and filter the feature out) when the column is missing or null.

• Type coercion: the left-hand value is cast to match the right-hand type, so ["score", "eq", 100] matches whether the column stores 100 or "100".

Common patterns

There is no single "between" operator — combine two comparisons:

"filters": [["temperature", "ge", 0], "and", ["temperature", "le", 100]]

Check that a value exists and is non-empty:

"filters": [["name", "isnt", null], "and", ["name", "ne", ""]]

Three or more conditions must be written as nested pairs, not a flat list:

// WRONG: [a, "and", b, "and", c]
// RIGHT:
"filters": [["a", "eq", 1], "and", [["b", "eq", 2], "or", ["c", "eq", 3]]]