QGIS/resources/function_help/json/coalesce

{
  "name": "coalesce",
  "type": "function",
  "groups": ["Conditionals"],
  "description": "Returns the first non-NULL value from the expression list.<br>This function can take any number of arguments.",
  "variableLenArguments": true,
  "arguments": [{
    "arg": "expression1",
    "syntaxOnly": true
  }, {
    "arg": "expression2",
    "syntaxOnly": true
  }, {
    "arg": "expression",
    "descOnly": true,
    "description": "any valid expression or value, regardless of type."
  }],
  "examples": [{
    "expression": "coalesce(NULL, 2)",
    "returns": "2"
  }, {
    "expression": "coalesce(NULL, 2, 3)",
    "returns": "2"
  }, {
    "expression": "coalesce(7, NULL, 3*2)",
    "returns": "7"
  }, {
    "expression": "coalesce(\"fieldA\", \"fallbackField\", 'ERROR')",
    "returns": "value of fieldA if it is non-NULL else the value of \"fallbackField\" or the string 'ERROR' if both are NULL"
  }],
  "tags": ["list", "first", "arguments", "null"]
}