# Data Storage not showing decoded data and only stores data two times a day

**URL:** <https://www.thethingsnetwork.org/forum/t/data-storage-not-showing-decoded-data-and-only-stores-data-two-times-a-day/39316>\
**Category:** How to get started\
**Created:** [August 18, 2020, 3:44pm UTC](https://www.thethingsnetwork.org/forum/t/data-storage-not-showing-decoded-data-and-only-stores-data-two-times-a-day/39316 "2020-08-18T15:44:07Z")\
**Posts on this page:** 1\
**Showing post:** 9

<div class="post-metadata">

**Author:** ![arjanvanb](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/arjanvanb/32/46626_2.png) [@arjanvanb](https://www.thethingsnetwork.org/forum/u/arjanvanb)\
**Post date:** [August 18, 2020, 7:48pm UTC](https://www.thethingsnetwork.org/forum/t/data-storage-not-showing-decoded-data-and-only-stores-data-two-times-a-day/39316/9 "2020-08-18T19:48:08Z")

</div>

> [@arjanvanb](#):
>
> Anything funny when comparing data that is received in the HTTP Integration but not stored, to data that is handled by both?

Answering my own question: I guess they differ in `null` values?

It seems the Data Storage Integration does not support `null` values…

One can easily test by just returning some hardcoded JSON result in the Decoder, and then use Simulate uplink (with a random payload) on a device’s Overview page to trigger the Decoder and the integrations. No need to abuse the Fair Access Policy for that:

![Simulate uplink](https://www.thethingsnetwork.org/forum/uploads/default/original/3X/d/0/d0866316339a4a3b8c86474d221c19ec06e40390.png)

(To automate this, [look at `ttnctl devices simulate`](https://www.thethingsnetwork.org/docs/network/cli/api.html#ttnctl-devices-simulate).)

Storage silently fails for this:

```javascript
function Decoder(bytes, port) {
  return {
    "bytes": "ME9LIjE4MDk1Ljg3NzAibC9oIjE4MDk1Ljg3NzAia2cvaA==",
    "decode_data_hex": "0x30,0x4f,0x4b,0x22,0x31,0x38,0x30,0x39,0x35,0x2e,0x38,0x37,0x37,0x30,0x22,0x6c,0x2f,0x68,0x22,0x31,0x38,0x30,0x39,0x35,0x2e,0x38,0x37,0x37,0x30,0x22,0x6b,0x67,0x2f,0x68",
    "health_status": "OK",
    "mass_flow_unit": "kg/h",
    "mass_flow_value": 18095.877,
    "totalizer1_unit": null,
    "totalizer1_value": null,
    "totalizer2_unit": null,
    "totalizer2_value": null,
    "totalizer3_unit": null,
    "totalizer3_value": null,
    "volume_flow_unit": "l/h",
    "volume_flow_value": 18095.877
  }
}

```

Removing the attributes with `null` values, or using `undefined`, does work:

```javascript
function Decoder(bytes, port) {
  return {
    ...,
    "totalizer1_unit": undefined,
    "totalizer1_value": undefined,
    "totalizer2_unit": undefined,
    "totalizer2_value": undefined,
    "totalizer3_unit": undefined,
    "totalizer3_value": undefined,
    ...
  };
}

```

I wonder if things changed, but I guess not.

I’ve always seen `null` values in the output of the Data Storage Integration, but that’s probably due to the following: changing the Decoder, or conditionally including specific attributes, also affects _fetching_ existing/other data from the Data Storage Integration. Any attributes added _after_ data was already stored, or outputted conditionally, are outputted with `null` values for old/other data. Likewise, any removed attributes are still outputted with `null` for new data (even when only new data is returned in the time period of the query).

In other words: it seems all returned items all have the very same attributes, though some may be `null` when not defined for that very item. That makes it looks like `null` was supported, but I guess it never was.

This does not explain why some items are stored without any decoded values, but I’ll leave that investigation to you. 😉

Aside: note that the Decoder is executed upon receiving the data, not when fetching it from the Data Storage Integration. You can easily test by adding something like `dummy: new Date().toISOString()` in the output.

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