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Loads a variable based on a Structured Data Type (SDT) or Business Component from a JSON string received as a parameter.

Syntax

[&Boolean =] &var.FromJson(&String[, &Messages])

Where:
&String
    Attribute or variable string with the JSON content.

&var
    Variable based on an SDT or Business Component.

&Messages
   Variable based on the GeneXus's Messages data type. In case of an error, it will contain the error information. This Parameter is optional. 

Type returned:
Boolean.
    It returns False in case of having an error; otherwise, it returns True. The assignment of the return value is optional. 

Scope

Objects: ProcedureTransactionWeb Panel, Panel
Generators: .NET Framework .NET, Java

Description

The FromJson method loads the &var structure from the &String variable content. The variable's JSON format (&String) must be compatible with the variable based on an SDT or Business Component structure (&var).

Samples 

Consider a Structured Data Type defined as follows:

SDT1
{
     NumericMember: Numeric
     CharacterMember: Character
     GeoPointMember: GeoPoint
 }

Define the following code (for example in a Procedure Source or in a Web Panel / Panel Event):

 &VarBasedOnSDT1.FromJson('[{"NumericMember": 0,"CharacterMember":"ValueCharacter","GeoPointMember":"POINT(-56.10 -33.01)"}]')

The above code initializes the &VarBasedOnSDT1 variable.

Note that the GeoPointMember receives a value in WellKnowText Format (WKT). Another alternative, only available when generating for Android, is to pass a Geolocation domain format as parameter, as follows:

&VarBasedOnSDT1.FromJson('[{"NumericMember": 0,"CharacterMember":"VallueCharacter","GeoPointMember":"57.10, 68.9"}]')

Technical Details

Data Type Mapping

The GeneXus basic data types are mapped to JSON data types in this way:

  • Character, VarChar, LongVarChar → JSON string
  • Boolean → JSON Boolean
  • Numeric → JSON Number
  • Collections → an ordered sequence of values, comma-separated and enclosed in square brackets

Ignored SDT Properties

The following properties are ignored in the process of serializing an SDT to JSON:

References

See Also

ToJson Method
Structured Data Type (SDT) object

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