private Value castValue(Type type, Value value) {
   Value newValue = value;
   if (!value.isNull()
       && type.getTypeCode() != value.getType()
       && TypeFactory.canBeCastTo(value.getType(), type.getTypeCode())) {
     newValue = value.toType(type.getTypeCode());
   }
   return newValue;
 }
 public static void failIfNull(Value... values) throws FunctionException {
   for (Value value : values) {
     if (value.getType() == Type.NULL) {
       throw new FunctionException("Cannot operate in null values");
     }
   }
 }
  @Override
  public String check(int fieldId, Value value) throws DriverException {
    // In order to build pk indexes
    initializeEdition();
    // Check special case of auto-increment not-null fields
    Type type = getMetadata().getFieldType(fieldId);
    boolean autoIncrement = type.getBooleanConstraint(Constraint.AUTO_INCREMENT);
    if (autoIncrement && type.getBooleanConstraint(Constraint.NOT_NULL) && value.isNull()) {
      return null;
    }
    int fieldType = type.getTypeCode();
    // Test geometry types.
    if (TypeFactory.isVectorial(type.getTypeCode())) {
      int valueType = value.getType();

      if (!checkGeometry(valueType, fieldType)) {
        return "Can't put a "
            + TypeFactory.getTypeName(valueType)
            + " in a "
            + TypeFactory.getTypeName(fieldType)
            + " column.";
      }
    }
    // Cast value
    Value val = castValue(type, value);
    int broadType = TypeFactory.getBroaderType(fieldType, val.getType());
    if (val.getType() != broadType
        && val.getType() != Type.NULL
        && !checkGeometry(val.getType(), fieldType)
        && fieldType != Type.STRING) {
      return "Can't cast a "
          + TypeFactory.getTypeName(value.getType())
          + " to a "
          + TypeFactory.getTypeName(fieldType);
    }

    // Check constraints
    String fieldName = getMetadata().getFieldName(fieldId);
    String error = type.check(value);
    if (error != null) {
      return "Value at field " + getFieldName(fieldId) + " is not valid:" + error;
    }

    // Check uniqueness
    if (type.getBooleanConstraint(Constraint.UNIQUE) || type.getBooleanConstraint(Constraint.PK)) {
      // We assume a geometry field can't have unique constraint
      IndexQuery iq = new DefaultAlphaQuery(fieldName, value);
      Iterator<Integer> it = queryIndex(iq);
      while (it.hasNext()) {
        if (getFieldValue(it.next(), fieldId).equals(value).getAsBoolean()) {
          return fieldName + " column doesn't admit duplicates: " + value;
        }
      }
    }

    return null;
  }
 public static void failIfNotOfType(Value value, int type) throws FunctionException {
   if (type != value.getType()) {
     throw new FunctionException(value.toString() + " is not of type " + type);
   }
 }