SMART datagrid :: Expression Overivew

Concepts.Expression Overivew

SMART datagrid Expression is being used to display and handle the data in the grid. Although it contains several special operators to handle the value, it has been defined and implemented as simple as possible to be used in big data set.

In particular, since the priority of relational, comparison, logical operator has been integrated into one in the existing language, it must be enclosed in brackets if necessary. Expression text except the value is not case sensitive.

It is used in EditValidation.expression, DynamicStyle.expression, etc.

1. Syntax Grammer

Expression ::= ComparisonExpression (LogicalOperator ComparisonExpression)*
ComparisonExpression ::= SimpleExpression (ComparisonOperator SimpleExpression | SetOperator ExpressionList)*
ExpressionList ::= "()" | "(" SimpleExpression ("," SimpleExpression)* ")"
SimpleExpression ::= Term *(AddingOperator Term)
Term ::= Factor (MultiplyingOperator Factor)*
Factor ::= "(" Expression ")" | Variable | Constant | Converting Factor | Unary Factor
Constant ::= Unsigned Number | Charactor String | null | empty | defined | nan | true | false

2. Operators

It displays from a high priority. There is no priority between operators involved in the same group. If you want to give priority by force, you should enclose in brackets. The priority of Set Operator and Comparison Operator is the same.

Table-1 Constants

Operator	Explanation	Example
null	JavaScript null. Use is, is not as operand only.	value is null
empty	Empty value. undefined, null, Empty String. Use is, is not as operand only.	value is empty
defined	The value not JavaScript undefiend. Use is, is not as operand only.	value is defined
nan	JavaScript NaN. Use is, is not as operand only.	value is nan
true, false	JavaScript true, false	value == true

Table-2 Converting operator

Operator	Explanation	Example	Result
str	Convert to String	str 100	'100'
num	Convert to Number	num '199'	199
int	Convert to Integer	int '199.9'	int
date	Convert to Date. Compare to Date.getTime() value when compare the converted two values.	date '2010/11/11' <= local date date('2010-11-11') <= utc date date('2010-11-11T00:00:00+09:00')	It should be the string which can be transferred by JavaScript Date Object Constructor. In particular, in order to run data comparison operation including time value in all browsers equally, you must use ISO standard format including time zone. Please refer to Date.parse function.
bool	Convert to Boolean	bool '1'	true

Table-3 Unaray Operator

Operator	Explanation	Example	Result
not, !	Denial	not true, ! true	false
-	Negative	-100	-100
+	Positive	+100	100
len	String Length	len 'abcd'	4
rand	Random Integer greater than 0 and less than parameter	rand 100	15
srand	Ascill string of the length specified by parameter	srand 7	'xfeDfdG'
lower	Change the string specified by parameter to lower case string	lower 'AbcdEf'	'abcdef'
upper	Change the string specified by parameter to upper case string	upper 'AbcdEf'	'ABCDEF'

Table-4 Multiplying Operator

Operator	Explanation	Example	Result
*	Multiplication	11 * 2	22
/	Division	5 / 2	2.5
div	Integer Division	5 div 2	2
% (mod)	Remainder	5 % 2, 5 mod 2	1

Table-5 Adding Operator

Operator	Explanation	Example	Result
+	Plus	11 + 2	13
-	Minus	5 - 2	3

Table-6 Comparison Operator

Operator	Explanation	Example	Result
==, !=, <, <=, >, >=	Comparison		true\|false
is	Comparison	value is null, value is empty, value is defined, value is nan	true\|false
is not	Comparison	value is not null, value is not empty, value is not defined, value is not nan	true\|false
match, not match	Regular expression	value match '[^d.-+]'	true\|false
imatch, not imatch	Regular expression not case sensitive	value match '[^d.-+]'	true\|false
like, not like	Text comparison	value like '%abc%', value not like '%abc', value like 'abc%	true\|false
ilike, not ilike	Text comparison not case sensitive	value ilike '%abc%', value not ilike '%abc', value ilike 'abc%	true\|false

*The priority of Set operators are the same as Comparison operators.

Table-7 Set Operator

Operator	Explanation	Example	Result
in, not in	Include	3 in (1, 2 3), value not in ('a', 'b', 'c') Right operand should be a list of being enclosed in brackets ('(', ')') and items being separated by comma (',').	true\|false

Table-8 Logical Operator

Operator	Explanation	Example	Result
&&	Logical AND(And)	true && false	false
\|\|	Logical OR(Or)	true \|\| false	true

Code -1

    grid.setColumns([{
        fieldName: 'product_id',
        styles: [{
            expression: "value > 1000",
            styles: {
                background: "#01ff0000",
                ...
            }
        }]
    ], {
        ...
    }]);

Code -2

    column.setValidations([{
        "expression": "value is not empty",
        "level": DataLudi.ValidationLevel.ERROR,
        "message": strings["CommCodeMsg"]
    }]);

See Also: DynamicStyle; EditValidation; DataColumn.dynamicStyles; GridBody.dynamicStyles

Examples: Column Dynamic Styles; Default Dynamic Styles; Cell Validation; Row Validation