collection.query( )

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4D v18

collection.query( )

Description

The collection.query( ) method returns all elements of a collection of objects that match the search conditions defined by queryString and (optionally) value and querySettings. If the original collection is a shared collection, the returned collection is also a shared collection.

Note: This method does not modify the original collection.

The queryString parameter uses the following syntax:

propertyPath comparator value {logicalOperator propertyPath comparator value}

For detailed information on how to build a query using queryString, value and querySettings parameters, please refer to the dataClass.query( ) method description.

Example 1

 C_COLLECTION($c)

 $c:=New collection

 $c.push(New object("name";"Cleveland";"zc";35049))

 $c.push(New object("name";"Blountsville";"zc";35031))

 $c.push(New object("name";"Adger";"zc";35006))

 $c.push(New object("name";"Clanton";"zc";35046))

 $c.push(New object("name";"Clanton";"zc";35045))

 $c2:=$c.query("name = :1";"Cleveland") //$c2=[{name:Cleveland,zc:35049}]

 $c3:=$c.query("zc > 35040") //$c3=[{name:Cleveland,zc:35049},{name:Clanton,zc:35046},{name:Clanton,zc:35045}]

Example 2

 C_COLLECTION($c)

 $c:=New collection

 $c.push(New object("name";"Smith";"dateHired";!22-05-2002!;"age";45))

 $c.push(New object("name";"Wesson";"dateHired";!30-11-2017!))

 $c.push(New object("name";"Winch";"dateHired";!16-05-2018!;"age";36))

 $c.push(New object("name";"Sterling";"dateHired";!10-5-1999!;"age";Null))

 $c.push(New object("name";"Mark";"dateHired";!01-01-2002!))

This example returns persons whose name contains "in":

 $col:=$c.query("name = :1";"@in@")

  //$col=[{name:Winch...},{name:Sterling...}]

This example returns persons whose name does not begin with a string from a variable (entered by the user, for example):

 $col:=$c.query("name # :1";$aString+"@")

  //if $astring="W"

  //$col=[{name:Smith...},{name:Sterling...},{name:Mark...}]

This example returns persons whose age is not known (property set to null or undefined):

 $col:=$c.query("age=null") //placeholders not allowed with "null"

  //$col=[{name:Wesson...},{name:Sterling...},{name:Mark...}]

This example returns persons hired more than 90 days ago:

 $col:=$c.query("dateHired < :1";(Current date-90))

  //$col=[{name:Smith...},{name:Sterling...},{name:Mark...}] if today is 01/10/2018

Note: This last example requires that the "Use date type instead of ISO date format in objects" compatibility option is checked (see Compatibility page).

Example 3

More examples of queries can be found in the dataClass.query( ) page.