Transformation helpers in util.transform

util.transform contains helper methods that make it easier to perform complex operations against data sources.

util.transform.toDynamoDBFilterExpression(filterObject: DynamoDBFilterObject) : string

Converts an input string to a filter expression for use with DynamoDB. We recommend using toDynamoDBFilterExpression with built-in module functions.

util.transform.toElasticsearchQueryDSL(object: OpenSearchQueryObject) : string

Converts the given input into its equivalent OpenSearch Query DSL expression, returning it as a JSON string.

Example input:


util.transform.toElasticsearchQueryDSL({
    "upvotes":{
        "ne":15,
        "range":[
            10,
            20
        ]
    },
    "title":{
        "eq":"hihihi",
        "wildcard":"h*i"
    }
  })

Example output:


{
    "bool":{
      "must":[
          {
            "bool":{
              "must":[
                  {
                    "bool":{
                      "must_not":{
                        "term":{
                          "upvotes":15
                        }
                      }
                    }
                  },
                  {
                    "range":{
                      "upvotes":{
                        "gte":10,
                        "lte":20
                      }
                    }
                  }
              ]
            }
          },
          {
            "bool":{
              "must":[
                  {
                    "term":{
                      "title":"hihihi"
                    }
                  },
                  {
                  "wildcard":{
                      "title":"h*i"
                    }
                  }
              ]
            }
          }
      ]
    }
}

Note

The default operator is assumed to be AND.

util.transform.toSubscriptionFilter(objFilter, ignoredFields?, rules?): SubscriptionFilter

Converts a Map input object to a SubscriptionFilter expression object. The util.transform.toSubscriptionFilter method is used as an input to the extensions.setSubscriptionFilter() extension. For more information, see Extensions.

Note

The parameters and return statement is listed below:

Parameters

objFilter: SubscriptionFilterObject

A Map input object that's converted to the SubscriptionFilter expression object.
ignoredFields: SubscriptionFilterExcludeKeysType (optional)

A List of field names in the first object that will be ignored.
rules: SubscriptionFilterRuleObject (optional)

A Map input object with strict rules that's included when you're constructing the SubscriptionFilter expression object. These strict rules will be included in the SubscriptionFilter expression object so that at least one of the rules will be satisfied to pass the subscription filter.

Response

Returns a SubscriptionFilter.

util.transform.toSubscriptionFilter(Map, List)

The first argument is the Map input object that's converted to the SubscriptionFilter expression object. The second argument is a List of field names that are ignored in the first Map input object while constructing the SubscriptionFilter expression object.

util.transform.toSubscriptionFilter(Map, List, Map)

util.transform.toDynamoDBConditionExpression(conditionObject)

Creates a DynamoDB condition expression.

Subscription filter arguments

The following table explains the how the arguments of the following utilities are defined:

Util.transform.toSubscriptionFilter(objFilter, ignoredFields?, rules?): SubscriptionFilter

Argument 1: Map

Argument 1 is a Map object with the following key values:

field names
"and"
"or"

For field names as keys, the conditions on these fields' entries are in the form of "operator" : "value".

The following example shows how entries can be added to the Map:


"field_name" : {
                    "operator1" : value             
               }

## We can have multiple conditions for the same field_name: 

"field_name" : {
                    "operator1" : value             
                    "operator2" : value
                    .
                    .
                    .                  
               }

When a field has two or more conditions on it, all of these conditions are considered to use the OR operation.

The input Map can also have "and" and "or" as keys, implying that all entries within these should be joined using AND or OR logic depending on the key. The key values "and" and "or" expect an array of conditions.


"and" : [
            
            {
                "field_name1" : {
                    "operator1" : value             
                }
             },
             
             {
                "field_name2" : {
                    "operator1" : value             
                }
             },
             .
             .
        ].

Note that you can nest "and" and "or". That is, you can have nested "and"/"or" within another "and"/"or" block. However, this doesn't work for simple fields.


"and" : [
            
            {
                "field_name1" : {
                    "operator" : value             
                }
             },
             
             {
                "or" : [
                            {
                                "field_name2" : {
                                    "operator" : value             
                                }
                            },
                            
                            {
                                "field_name3" : {
                                    "operator" : value             
                                }
                            }
              
                        ].

The following example shows an input of argument 1 using util.transform.toSubscriptionFilter(Map) : Map.

Input(s)

Argument 1: Map:


{
  "percentageUp": {
    "lte": 50,
    "gte": 20
  },
  "and": [
    {
      "title": {
        "ne": "Book1"
      }
    },
    {
      "downvotes": {
        "gt": 2000
      }
    }
  ],
  "or": [
    {
      "author": {
        "eq": "Admin"
      }
    },
    {
      "isPublished": {
        "eq": false
      }
    }
  ]
}

Output

The result is a Map object:


{
  "filterGroup": [
    {
      "filters": [
        {
          "fieldName": "percentageUp",
          "operator": "lte",
          "value": 50
        },
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 2000
        },
        {
          "fieldName": "author",
          "operator": "eq",
          "value": "Admin"
        }
      ]
    },
    {
      "filters": [
        {
          "fieldName": "percentageUp",
          "operator": "lte",
          "value": 50
        },
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 2000
        },
        {
          "fieldName": "isPublished",
          "operator": "eq",
          "value": false
        }
      ]
    },
    {
      "filters": [
        {
          "fieldName": "percentageUp",
          "operator": "gte",
          "value": 20
        },
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 2000
        },
        {
          "fieldName": "author",
          "operator": "eq",
          "value": "Admin"
        }
      ]
    },
    {
      "filters": [
        {
          "fieldName": "percentageUp",
          "operator": "gte",
          "value": 20
        },
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 2000
        },
        {
          "fieldName": "isPublished",
          "operator": "eq",
          "value": false
        }
      ]
    }
  ]
}

Argument 2: List

Argument 2 contains a List of field names that shouldn't be considered in the input Map (argument 1) while constructing the SubscriptionFilter expression object. The List can also be empty.

The following example shows the inputs of argument 1 and argument 2 using util.transform.toSubscriptionFilter(Map, List) : Map.

Input(s)

Argument 1: Map:


{
  "percentageUp": {
    "lte": 50,
    "gte": 20
  },
  "and": [
    {
      "title": {
        "ne": "Book1"
      }
    },
    {
      "downvotes": {
        "gt": 20
      }
    }
  ],
  "or": [
    {
      "author": {
        "eq": "Admin"
      }
    },
    {
      "isPublished": {
        "eq": false
      }
    }
  ]
}

Argument 2: List:


["percentageUp", "author"]

Output

The result is a Map object:


{
  "filterGroup": [
    {
      "filters": [
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 20
        },
        {
          "fieldName": "isPublished",
          "operator": "eq",
          "value": false
        }
      ]
    }
  ]
}

Argument 3: Map

Argument 3 is a Map object that has field names as key values (cannot have "and" or "or"). For field names as keys, the conditions on these fields are entries in the form of "operator" : "value". Unlike argument 1, argument 3 cannot have multiple conditions in the same key. In addition, argument 3 doesn't have an "and" or "or" clause, so there's no nesting involved either.

Argument 3 represents a list of strict rules, which are added to the SubscriptionFilter expression object so that at least one of these conditions is met to pass the filter.


{
  "fieldname1": {
    "operator": value
  },
  "fieldname2": {
    "operator": value
  }
}
.
.
.

The following example shows the inputs of argument 1, argument 2, and argument 3 using util.transform.toSubscriptionFilter(Map, List, Map) : Map.

Input(s)

Argument 1: Map:


{
  "percentageUp": {
    "lte": 50,
    "gte": 20
  },
  "and": [
    {
      "title": {
        "ne": "Book1"
      }
    },
    {
      "downvotes": {
        "lt": 20
      }
    }
  ],
  "or": [
    {
      "author": {
        "eq": "Admin"
      }
    },
    {
      "isPublished": {
        "eq": false
      }
    }
  ]
}

Argument 2: List:


["percentageUp", "author"]

Argument 3: Map:


{
  "upvotes": {
    "gte": 250
  },
  "author": {
    "eq": "Person1"
  }
}

Output

The result is a Map object:


{
  "filterGroup": [
    {
      "filters": [
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 20
        },
        {
          "fieldName": "isPublished",
          "operator": "eq",
          "value": false
        },
        {
          "fieldName": "upvotes",
          "operator": "gte",
          "value": 250
        }
      ]
    },
    {
      "filters": [
        {
          "fieldName": "title",
          "operator": "ne",
          "value": "Book1"
        },
        {
          "fieldName": "downvotes",
          "operator": "gt",
          "value": 20
        },
        {
          "fieldName": "isPublished",
          "operator": "eq",
          "value": false
        },
        {
          "fieldName": "author",
          "operator": "eq",
          "value": "Person1"
        }
      ]
    }
  ]
}

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