listTopics

JSON MQ "listTopics" action returns and filters a list of MQTT topics

The "listTopics" action lists the names of MQTT topics that the server is tracking.

  • You can return a filtered list by specifying a partial name in the "partialName" property.
  • You can include additional items in the list by searching for words contained in the item’s metadata.
  • Use "describeTopics" to get detailed information about specific MQTT topics.

 

Request examples

Minimal

{
  "action": "listTopics",
  "authToken": "replaceWithAuthTokenFromCreateSession"
}
 
 

Maximal

{
  "api": "mq",
  "apiVersion": "1.0",
  "requestId": "2",
  "action": "listTopics",
  "params": {
    "partialName": "test",
    "search": null,
    "dataFormat": "arrays",
    "skipRecords": null,
    "maxRecords": 20,
    "label": {
      "group": "group name",
      "name": "label name"
    }
  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}
 
 

 

Response examples

Minimal

{
  "result": {
    "data": [
      "test/ReasonCodes",
      "test/SharedSubscriptions",
      "test/topic1",
      "test/topic2"
    ]
  },
  "errorCode": 0,
  "errorMessage": "",
  "authToken": "replaceWithAuthTokenFromCreateSession"
}
 
 

Maximal

{
  "result": {
    "data": [
      "test/ReasonCodes",
      "test/SharedSubscriptions",
      "test/topic1",
      "test/topic2"
    ]
  },
  "requestId": "2",
  "errorCode": 0,
  "errorMessage": "",
  "authToken": "replaceWithAuthTokenFromCreateSession"
}
 
 

 

Properties

Request properties ("params")

Property Description Default Topic Limits (inclusive)

dataFormat

The "dataFormat" property defines the format of the "data" property. The default format is an array of arrays. The alternative is an array of objects. The default for "dataFormat" can be changed during a "createSession" action by assigning a different value to the "dataFormat" property in "defaultResponseOptions".

There are three different (but similar) versions of the "dataFormat" property:

Two of those versions occur in a request, and another occurs in a response. They all indicate how data is formatted.

  • "dataFormat" in the request in "responseOptions" determines how the "data" property in the response is formatted.
    • Possible values include:
      • "arrays"
        • This is the default and causes the server to return results as an array of arrays, which is the most efficient.
      • "objects"
        • This returns results as an array of objects. This is less efficient but is simpler to generate, read, and troubleshoot.
  • "dataFormat" in the request in the "params" object notifies the server how the "sourceData" property is formatted in the request. This version is rarely used because of the default "autoDetect" behavior.
    • Possible values include:
      • "arrays"
        • This causes the server to return results as an array of arrays, which is the most efficient.
      • "objects"
        • This returns results as an array of objects. This is less efficient but is simpler to generate, read, and troubleshoot.
      • "autoDetect"
        • This is the default, and the server automatically detects the format of the data in the "sourceData" property.
  • "dataFormat" in the response shows the client how the server formatted the "data" property.
    • Possible values include:
      • "arrays"
        • This is the default and causes the server to return results as an array of arrays, which is the most efficient.
      • "objects"
        • This returns results as an array of objects. This is less efficient but is simpler to generate, read, and troubleshoot.
 Optional with default of "arrays" string

"default"

"arrays"

"objects"

label

The "label" property assigns a label to an object. The "label" object contains "group" and "name" properties that uniquely identify a label. If you omit the "group" and "name" properties, they default to the empty string, "", which is a valid group and name for a label.

A label is a tag that you can add to some objects, such as an MQTT topic or session. You can use list actions such as "listTopics" and "listMqSessions" to find objects with a specific label.

The "label" property is mutually exclusive from the "labelId" property.

 Optional with default of null object 
"label": {
  "group": "group name",
  "name": "label name"
}

label

.group

The "group" property groups labels into a lookup list or tag set. It is a namespace for a set of labels that identifies their purpose. You can use the "listLabelGroups" action to return the list groups. You can use the "listLabels" action to return labels in one or more groups. 

The "group" and "name" properties work together to uniquely identify each label. They are its natural key. A group assigned to the empty string "" is the default group.

The group name may contain up to 64 bytes of UTF-8 encoded characters.

When you assign a group name to a label, the server automatically checks if the group name exists in the list of groups that the "listLabelGroups" action returns. If the group name does not exist, the server adds the group name to the list. When you rename a group assigned to a label, the server automatically adds a new group name to the list and removes the previous group name if no other label uses it.

Tip If your application creates many groups, you can use a delimiter character, such as the forward slash / in your group names to create a group hierarchy. Include the delimiter after each part of the hierarchy and at the end of the group name. In the "listLabels" action, you can use the "partialGroupFilter" filter to return subsets of groups in the hierarchy. For example, you if have groups named "product/size/", "product/weight/", "product/ranking/", "person/gender/", and "person/ranking/", you can set the "partialGroupFilter" to "product/" to return the product groups.

 Optional with default of "" string 1 to 64 bytes

label

.name

The "name" property is the name of a label or field. 

The "group" and "name" properties combined uniquely identify each label. The "createLabel" and "alterLabel" actions return an error if the "group" and "name" properties do not create a unique label name.

The "id" property also uniquely identifies each label, so you can rename a label's group and name without breaking "id" references to the label.

 Required - No default value string 1 to 64 bytes

maxRecords

 The "maxRecords" property specifies the maximum number of records to be returned. It is used with "skipRecords" to paginate the results. If the value is not null or omitted, the server returns the maximum number of results specified by "maxRecords". Optional with default of 20  integer -1 to 65535

partialName

The "partialName" property returns code packages with code names that match the value of "partialName". The match starts at the name's beginning, making it a "starts with" match instead of a "substring" match. If the partial name is empty, null, or omitted, it matches all names.

 Optional with default of "" string 1 to 64 bytes

search

The "search" property searches the content of the "metadata" property that is part of each topic and integration table.

  • If there is nothing in the "metadata" property for a topic or an integration table, there is nothing to search for, resulting in an empty array in the "data" property in the response.
  • The "metadata" property is a JSON field, meaning you can put a valid JSON in it — for example, a string or object.
 Optional with default of "" string 0 to 64 bytes

skipRecords

 The "skipRecords" property specifies the number of records to skip over when paginating the results. It is used with "maxRecords" to paginate the results. If the value is not null or omitted, the server returns results from the beginning. If it is > 0, the server skips over the specified number of records and returns results starting from that point up until it returns the maximum number of results as defined by "maxRecords". Optional with default of 0 integer 0 to 9223372036854775807

 

Response properties ("result")

Property Description Type Limits (inclusive)

data

The "data" property contains a response message. Its contents are defined by the action. It is an empty array when no results are available. The following is an example of the data property from a code package action.

  "result": {
    "data": [
      {
        "codeId": 6,
        "databaseName": "faircom",
        "ownerName": "admin",
        "codeName": "convertAndCategorizeTemperature",
        "codeVersion": 1,
        "clonedCodeId": 1,
        "codeStatus": "active",
        "codeLanguage": "javascript",
        "serviceName": "javascript",
        "codeType": "module",
        "description": "optional new description",
        "metadata": {},
        "createdBy": "ADMIN",
        "createdOn": "2025-08-25T21:48:38.109",
        "updatedBy": "ADMIN",
        "updatedOn": "2025-08-25T21:48:38.109",
        "comment": "Cloned from convertTemperature",
        "codeFormat": "utf8"
      },
    ]
 array of objects The action determines its contents.

 

Was this article helpful?

Give feedback about this article

Related Articles