Ensure a filter exists in a CaQL query.

ensure_caql_filter.js

var caql = require('caql');
var CaqlDecompiler = require('caql-decompiler');

function checkExpression(expr) {
  if (expr.type === 'Conjunction' && !expr.isNegated) {
    return checkExpression(expr.left) || checkExpression(expr.right);
  }

  return expr.type === 'ComparisonPredicate'
      && expr.field === 'type'
      && expr.operator === 'eq'
      && JSON.parse(expr.value) === 'photocell'
      && !expr.isNegated;
}

var query = 'where intensity >= 3.5';

var ast;
try {
  ast = caql.parse(query);
} catch(e) {
  console.error(e);
  process.exit();
}

var hasFilterExpression = checkExpression(ast.filterNode.expression);

var ql = query;

if (!hasFilterExpression) {
  var expr = ast.filterNode.expression;
  var filter = new caql.Ast.ComparisonPredicateNode('type', 'eq', JSON.stringify('photocell'));
  ast.filterNode.expression = new caql.Ast.ConjunctionNode(filter, expr);

  var decompiler = new CaqlDecompiler();
  ql = decompiler.decompile(ast);
}


console.log(ql);