Query Grammar

Data Types

The following are the supported basic data types by the DVR Query language:

• Integer A signed 64-bit integer data type. Example: 10, -12

• String A sequence of characters. Example: "Hello, world!"

• Boolean A binary value that can be either true or false

Operators

The list of supported operators:

• Boolean Operators:

  • or

  • and

• Relational Operators: >, >=, <, <=

  • Applies to integer

• Equality Operators

  • Equality operator: == Applies to boolean, integer, and string. In the case of a string, this is a case-sensitive comparison.

  • Inequality operator: != Applies to boolean, integer, string

  • String-specific Relational Operations

    • ~!= Case-insensitive inequality operation on a string

    • ~== Case-insensitive equality operation on string

Variable and Literals

The zkPass Query language also defines the following concepts:

• Variable The variable corresponds to the key name of the key/value json element in the query data. To reference nested elements in the json data, delimiter “.” is used as the path separator. The variable must appear on the left-hand side of a relational expression.

• Literal (Constant) The constant value is compared to the variable's value. The literal must appear on the right-hand side of a relational expression. The data type of the literal must match that of the variable.

Grammar BNF

<query> ::= <boolean-expression>

<boolean-expression> ::= "{" <logical-operator> ": [" <expression-list> "] "}"

<logical-operator> ::= "and" | "or"

<expression-list> ::= <expression> | <expression> "," <expression-list>
<expression> ::= <relational-expression> | <boolean-expression>

<relational-expression> ::= "{" <relational-operator> ": [" <variable> "," <literal> "] "}"

<relational-operator> ::= "==" | "!=" | ">" | ">=" | "<" | "<=" | "~==" | "~!="

<variable> ::= <string>

<literal> ::= <integer> | <string> | <boolean>

<integer> ::= ["-"] <digit>+

<string> ::= """ <characters> """

<boolean> ::= "true" | "false"

<characters> ::= <character>*
<character> ::= <letter> | <digit> | <special-character> | " "

<special-character> ::= "!" | "@" | "#" | "$" | "%" | "^" | "&" | "*" | "(" | ")" | "-" | "+" | "=" | "[" | "]" | "{" | "}" | "|" | ":" | ";" | "'" | "<" | ">" | "," | "." | "/" | "?" | "~"

<letter> ::= "a" ... "z" | "A" ... "Z"
<digit> ::= "0" ... "9"

Query Example

[
  {
    assign: {
      account_holder: {
        and: [
          { "==": [{ dvar: "bcaDocID" }, "DOC897923CP"] },
          { "~==": [{ dvar: "personalInfo.firstName" }, "Ramana"] },
          { "~==": [{ dvar: "personalInfo.lastName" }, "Maharshi"] },
          {
            "~==": [{ dvar: "personalInfo.driverLicenseNumber" }, "DL77108108"],
          },
          {
            ">=": [{ dvar: "financialInfo.creditRatings.pefindo" }, 650],
          },
          {
            ">=": [
              { dvar: "financialInfo.accounts.savings.balance" },
              55000000,
            ],
          },
        ],
      },
    },
  },
  { output: { result: { lvar: "account_holder" } } },
]