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sunus0001
sunus0001
February 3, 2022
Solved

I have a webAPI that creates record in Appian DB, I want to show custom error message for each field using an expression rule,where i can call this expression rule in API

  • February 3, 2022
  • 8 replies
  • 0 views

HI Appian team,

I need help from you to show custom error message in a web api, i have asked the same question 4 months ago, in that i got a suggestion that to create an expression rule and validate the api using that ,but where i can use expression rule in an API, Please find the code attached to understand webapi code and expression rule i created. How can i call the expression rule within webapi to validate API for errors,Is anyone have done similar requirement ,if yes please post code snippet for us.

thanks

a!startProcess(
  processModel: cons!PF_Create_Request_WithChanges,
  processParameters: 
  a!fromJson(
    http!request.body)  
    ,
    onSuccess: a!httpResponse(
      statusCode: 200,
      headers: {
        a!httpHeader(name: "Content-Type", value: "application/json")
      },
      body: a!toJson(
        fv!processInfo
      )
    ),
    onError: a!httpResponse(
      statusCode: 500,
      headers: {
        a!httpHeader(name: "Content-Type", value: "application/json")
      },
      body: a!toJson(
        {
          error: "There was an error starting the process"
        }
      )
    )
)
if(
  rule!GLB_isBlank(
    ri!PF_Request.GBEID
  ),

a!toJson(
  {
    field: ri!PF_Request.GBEID,
    error: "Error in GBEID field"
  }
),
true()
)

Please find the above code for web api and expression rule please guide us.

please find the url below for my previous post.

https://community.appian.com/discussions/f/process/22021/how-to-show-the-specific-custom-error-message-for-an-appian-web-api-which-is-used-for-creating-records-in-appian

Thanks  & Regards

Sunu Sam

Best answer by stefanhelzle0001

a!localVariables(
  local!validationresult: rule!yourValidationRule(
    input: a!fromJson(http!request.body)
  ),
  if(
    ,
    a!startProcess(
    .
    ),
    a!httpResponse(
    /* Error Messages */
    )
  )
)

8 replies

stefanhelzle0001
stefanhelzle0001
Brainy
February 3, 2022

A Web API is just a piece of expression code evaluated when called. This means, you can create local variables etc. as in any other expression.

- pass incoming data to expression and store the result in a local

- if validation is OK, return positive message

- If validations fails, return JSON containing one or more error messages.

sunus0001
sunus0001Author
February 3, 2022

Thanks Stefan for the reply, am confused in terms of the input data, my input is just a json body, how can i get the table and its corresponding column values as parameters,can you help me with the code snippet for the above explanation, for me to understand better.

processParameters: a!fromJson(
http!request.body
), - this is input how can i pass this to an expression rule for validation of the data??

Thanks

Sunu Sam

stefanhelzle0001
stefanhelzle0001Answer
Brainy
February 3, 2022

a!localVariables(
  local!validationresult: rule!yourValidationRule(
    input: a!fromJson(http!request.body)
  ),
  if(
    ,
    a!startProcess(
    .
    ),
    a!httpResponse(
    /* Error Messages */
    )
  )
)

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