This section describes the functionality of the utility class FilterExpressionUtils, that provides a set of methods and utilities for building complex filtering expressions used in OntimizeWeb.

Filtering expression

A filtering expression is an object that defines an operation between two operands. The interface Expression contains the basic structure of a filtering expression. The second operand may be omitted in some expressions, for example, filtering with a NULL value.

The filtering expression structure is the following;

{
  /** The left operand. */
  lop: string | Expression

  /** The operator. */
  op: string

  /** The right operand. */
  rop?: string | Expression
}

Operators

OntimizeWeb defines a set of operators used as the op parametter of Expression for building filtering expressions. This operators cover most important operations defined by every database management system and they are the following:

Operators
AND	TRUE if both logical expressions are TRUE
EQUAL	equal to a value
LESS	less than a value
LESS EQUAL	less than or equal to a value
LIKE	TRUE if the operand matches a pattern
MORE	more than a value
MORE EQUAL	more than or equal to a value
NOT EQUAL	not equal to a value
NOT LIKE	TRUE if the operand not matches a pattern
NULL	is NULL
NOT NULL	is not NULL
OR	TRUE if either logical expression is TRUE
IN	TRUE if the operand is contained in the provided values

All this operator are defined statically in FilterExpressionUtils class with the operator prefix OP_ (OP_AND, OP_EQUAL, etc.).

Filter building methods

OntimizeWeb defines a set of methods for building filtering expressions automatically. This methods are the following:

buildArrayExpressionLike
Builds an Expression instance for filtering the provided keys LIKE the value provided.
Parameters
keys any[]	the keys
value any	the value
Returns
Expression	the Expression

buildExpressionEquals
Builds an Expression instance for filtering the provided key EQUAL to the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionIsNotNull
Builds an Expression instance for filtering the provided key with a NOT NULL value.
Parameters
key string	the key
Returns
Expression	the Expression

buildExpressionIsNull
Builds an Expression instance for filtering the provided key with a NULL value.
Parameters
key string	the key
Returns
Expression	the Expression

buildExpressionLess
Builds an Expression instance for filtering the provided key LESS than the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionLessEqual
Builds an Expression instance for filtering the provided key LESS OR EQUAL to the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionLike
Builds an Expression instance for filtering the provided key LIKE the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionLikeEnd
Builds an Expression instance for filtering the provided key ENDS LIKE the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionLikeStart
Builds an Expression instance for filtering the provided key STARTS LIKE the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionMore
Builds an Expression instance for filtering the provided key MORE than the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionMoreEqual
Builds an Expression instance for filtering the provided key MORE OR EQUAL to the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionNotEquals
Builds an Expression instance for filtering the provided key NOT EQUAL to the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionNotLike
Builds an Expression instance for filtering the provided key NOT LIKE to the provided value.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionNullAndValue
Builds an Expression instance for filtering the provided key with two conditions: * The first filter the provided key with a NULL value. * The second filter the provided key EQUAL to the provided value. Both expressions are joined using the provided operator.
Parameters
key string	the key
value any	the value
Returns
Expression	the Expression

buildExpressionIn
Builds an Expression instance for filtering the provided key IN the provided values.
Parameters
key string	the key
values any	the values
Returns
Expression	the Expression

Utility methods

OntimizeWeb also defines a set of utility methos to help you building complex filtering expressions. This methods are the following:

buildBasicExpression
Builds a IBasicExpression instance from the filtering expression (Expression) provided.
Parameters
exp Expression	the filtering expression
Returns
BasicExpression	the basic expression

buildComplexExpression
Builds a complex Expression instance joining two expressions with the provided operator.
Parameters
expr1 Expression	the first filtering expression to join
expr2 Expression	the second filtering expression to join
op string	the joining operator
Returns
Expression	the complex filtering expression

buildExpressionFromObject
Builds an Expression instance from the provided object.
Parameters
obj any	the object
Returns
Expression	the Expression

buildFilterExpression
Builds an IFilterExpression instance from the filtering expression (Expression) provided.
Parameters
exp Expression	the filtering expression
Returns
IFilterExpression	the IFilterExpression

instanceofBasicExpression
Evaluates if the the expression provided is an instance of IBasicExpression.
Parameters
exp Expression	the filtering expression
Returns
boolean	true if the provided expression is an instance of IBasicExpression, false otherwise

instanceofExpression
Evaluates if an expresion is instance of Expression.
Parameters
exp any	the expression to evaluate
Returns
boolean	true if the provided expression is an instance of Expression, false otherwise

instanceofFilterExpression
Evaluates if an expresion is instance of IFilterExpression.
Parameters
exp any	the expression to evaluate
Returns
boolean	true if the provided expression is an instance of IFilterExpression, false otherwise

Examples

The following example shows how to buid a Basic expression for querying a table using the FilterExpressionUtils class. The expressions passed to the method buildBasicExpression or buildFilterExpression can be as complex as you need, in this case it is a simple like expression.

const filterExpr = FilterExpressionUtils.buildExpressionLike('EMPLOYEENAME', 'Caroline');
const basicExpr = FilterExpressionUtils.buildBasicExpression(filterExpr);

this.table.queryData(basicExpr);

The *filter sent to the backend results like the following:

"filter": {
  "@basic_expression": {
    "lop": "EMPLOYEENAME",
    "op": "LIKE",
    "rop": "%Caroline%"
  }
}

It is possible to include additional filters that doesn’t belong to the Basic expression:

const filterExpr = FilterExpressionUtils.buildExpressionLike('EMPLOYEENAME', 'Caroline');
const basicExpr = FilterExpressionUtils.buildBasicExpression(filterExpr);

basicExpr['EMPLOYEETYPEID'] = 1;

this.table.queryData(basicExpr);

"filter": {
  "@basic_expression": {
    "lop": "EMPLOYEENAME",
    "op": "LIKE",
    "rop": "%Caroline%"
  },
  "EMPLOYEETYPEID": 1
}