Custom WHERE Clause Functions

Overview

The Immuta Policy Builder allows you to use custom functions that extend the PostgreSQL WHERE syntax. These custom functions can be seen as utilities that help you create policies easier. Using the Immuta Policy Builder, you can include these functions in your policy queries by choosing where in the sub-action drop-down menu.

Custom Functions

The @attributeValuesContains() Function

This function returns true for a given row if the provided column evaluates to an attribute value for which the querying user has a corresponding attribute value. This function requires two arguments and accepts no more than three arguments.

Parameters

#	Parameter	Type	Required	Description
1	Attribute Name	String	Required	The name of the attribute to retrieve values for
2	Column Name/SQL Expression	String	Required	The column that contains the value to match the attribute key against
3	Placeholder	String	Optional	A placeholder in case the list of values is empty

The @columnTagged() Function

This function returns the column name with the specified tag.

If this function is used in a Global Policy and the tag doesn't exist on a data source, the policy will not be applied.

Parameters

#	Parameter	Type	Required	Description
1	Tag Name	String	Required	The name of the tag

The @groupsContains() Function

This function returns true for a given row if the provided column evaluates to a group to which the querying user belongs. This function requires at least one argument.

Parameters

#	Parameter	Type	Required	Description
1	Column Name/SQL Expression	String	Required	The column that contains the value to match the group against
2	Placeholder	String	Optional	A placeholder in case the list of values is empty

The @hasAttribute() Function

This function returns a boolean indicating if the current user has the specified attribute name and value combination. If the specified attribute name or attribute value has a single quote, you will need to escape it using a \'\' expression within a custom WHERE policy.

Parameters

#	Parameter	Type	Required	Description
1	Attribute Name	String	Required	The name of the attribute
2	Attribute Value	String	Required	The value to correspond with the attribute name

The @iam Function

This function returns the IAM ID for the current user.

Parameters

None.

The @interpolatedComparison() Function

Deprecation notice

Support for this function has been deprecated.

The Interpolated Comparison function is perhaps the most complex custom WHERE clause function. It essentially generates chained WHERE clauses. As opposed to the rest of the custom WHERE clause functions, its output is not a list of values or a boolean, but rather the comparison itself.

The @interpolatedComparison() function does not work with Immuta's database integrations.

Parameters

#	Parameter	Type	Required	Description
1	Column Name	String	Required	The name of a column in the remote database to use in the left-hand side of the clauses
2	Comparison Operator	String	Required	The comparison operator to use to compare the column and array value
3	Literal Template	String	Required	A necessary SQL logic and the template string which will be replaced with an array
4	Template String to Replace	String	Required	The string to replace in Literal Template with the array value
5	Custom function	Function	Required	A tagged function¹. Valid functions: @groupsContains, @purposesContains and @attributeValuesContains
6	Logical (Chain) Operator	String	Required	The logical operator used to link each generated clause (AND, OR, etc.)

¹ A custom function will not accept a placeholder argument when used inside @interpolatedComparison.

Example

The following invocation of interpolatedComparison():

WHERE @interpolatedComparison("group", "=", "upper('##')", "##", @groupsContains, "OR")

is equivalent to writing the following SQL WHERE clause, given that a user belongs to two groups called founders and engineers:

WHERE ((group = upper('founders')) or (group = upper('engineers')))

The @isInGroups() Function

This function returns a boolean indicating if the current user is a member of all of the specified groups. If any of the specified groups has a single quote, you will need to escape it using a \'\' expression within a custom WHERE policy.

Parameters

#	Parameter	Type	Required	Description
1	Group names	Array (String)	Required	A list of group names, e.g. groups('group_a', 'group_b', 'group_c')

The @isUsingPurpose() Function

This function returns a boolean indicating if the current user is using the specified purpose. If the specified purpose has a single quote, you will need to escape it using a \'\' expression within a custom WHERE policy.

Parameters

#	Parameter	Type	Required	Description
1	Purpose	String	Required	The name of the purpose to check the user against

The @purposesContains() Function

This function returns true for a given row if the provided column evaluates to a purpose under which the querying user is currently acting. This function requires at least one argument and accepts no more than two arguments.

Parameters

#	Parameter	Type	Required	Description
1	Column Name/SQL Expression	String/Expression	Required	The column that contains the value to match the purpose against
2	Placeholder	String	Optional	A placeholder in case the list of values is empty

The @username Function

This function returns the current user's user name.

Parameters

None.