Allow null value in child "When a HTTP request is received"

[ishraqiyun77]

In the past when I've had to parse JSON, or construct a schema, and I need to allow for "null", this has always worked for me in Power Automate:

{
    "type": "object",
    "properties": {
        "accountId": {
            "type": "string"
        },
        "industryTags": {
            "type": [
                "string",
                "null"
            ]
        }
    }
}

This is also confirmed here: https://stackoverflow.com/a/56708378/3123109.

Now I'm trying to work on a child flow and need it to receive null values and it isn't working. The field doesn't show up in the parent child request:

If I change it to "type": "string", then it does show up. But then inevitably some data is sent over without industryTags and it fails.

So how do I allow for null values in this use case?

[abm]

Hi @ishraqiyun77 

Are you passing the null as expression?

Thanks

[ishraqiyun77]

No, I am just passing the value of the field from Dynamics 365. So if the field value is empty, it just passes it null.

[abm]

Hi @ishraqiyun77 

Thanks for your quick reply. What's the error you getting? Make sure the child flow input is not mandatory.

[ishraqiyun77]

That is one thing I was trying to figure out how to do was not make it mandatory. How do you do that in the JSON scheme declaration?

I don't have the error in front of me anymore, but it was something along the lines of: "Was expecting a string/integer, but received 'Null'."

[abm]

Hi @ishraqiyun77 

The JSON scheme declaration you described earlier is correct other than you haven't specified the null optional set for accountId. Believe this was a typo and you already taken care of it in your flow.

{
    "type": "object",
    "properties": {
        "accountId": {
            "type": "string"
        },
        "industryTags": {
            "type": [
                "string",
                "null"
            ]
        }
    }
}

[MinRao]

@ishraqiyun77 

Where (or how) you use the "industryTags" in your child?

I try to reproduce by following parent and child flow. the result is if "industryTags" pass to child is null, then "industryTags" is not included in the http request (not sent over), if has some value then it will be included in request.

[charlePA]

Did anyone has an answer to this?

I also facing the same issue. 

I try  doing this 

"type": [
                "string",
                "null"
            ]

but doesn't work.

Power automate wont save and if you try to validate it using paconn, it will gives you an error.

The response looks like this:

The error occurs because the 2nd item Count property is null.

{
	[
		{
			Name: "test 1",
			Count: 1
		},
		{
			Name: "test 2",
			Count: null
		}
	]
}