Documentation
General
- MDriven Architecture
- Build Enterprise Information Systems
- Complexity shows up almost immediately–get the tools to manage it
- Different types of bugs
- Enterprise architect information
- Fashion Gist and Modernity
- GistMDriven
- Main concepts definition
- MDriven Turnkey Architecture
- Model Driven
- Philosophy–where lies the value
- Reality and the theoretical best model
- Database OR Mapping
- User interface technologies
MDriven Designer
- Barcode - on Android - with Xamarin and MDriven
- Catching more information in your model
- Creating CustomControl that Shows Data in a Gantt Chart
- Custom controls in ViewModel aided Views
- Delayed Fetch
- Derivation expressions
- Derived settable attributes
- Diagrams in Diagrams
- Ecomdl
- Enumerations
- Enumerations in Modlr
- Exception starting
- GuardConstraints
- Making sense of legacy data–DB Reverse
- Material Design Icons
- MDriven Designer and Modlr extensions–exporting data
- MDriven Designer–a new Rename function to save you time
- MDriven In Xamarin
- MDrivenDesignerPropertyInspectorHints
- NugetProject
- Object Identity
- PersistenceMapperWEBAPIClient
- Plugins in Modlr
- PopUp action
- PreserveLegacyFilenames
- Property inspector
- Simulate login
- Styling WPF Applications and ViewModels
- Text formatting
- The Concept application WhenAndWhereProject
- UI First–or information first
- UIOverride
- Updates to AutoForm and Debugger after latest feedback
- Using other than standard Persistence Mappers per attribute
- Using WECPOF in runtime
- WECPOF
- WECPOF Goodies
- WPF Debugger
- Xmi
Modeling
- Angular Ext Component
- autocomplete
- autofocus
- BlobDownloadLink
- ClientSortable
- DataIsHtml
- DataIsImageUrl
- DataIsLink
- BlobType
- FixColSize
- FormatAttr
- HideHeading
- MaxFetch
- MaxFileSizeInBytes
- Placeholder
- Resizable
- SeekerSortable
- SkipStyleLogic
- StringFormat
- StringFormatAngular
- StringFormatRazor
- Switch
- Autofocus
- BlobDownloadLink
- Texttype
- MaxFetch
- A few words on linq
- Acting on object changes
- Case sensitive or not
- Char to int and back
- ClassFromString
- Collection of strings
- Comparing strings
- Convert string to bytes
- Creating numeric types
- Custom types and custom operations in OCL
- Deepclone
- Default String Representation and asString
- Encoding
- Escape codes
- Examples on collection operators
- Methods
- Number conversions
- Ocl hex to dec
- Regular expressions
- Set vs bag
- Split
- Split time string to value
- State value as a string
- Understanding OCL with reference to SQL
- Unique constraints on 1 to 1 links
- VerbalizePatterns
- addReturnIndexOf0
- add
- and
- append
- asBag
- asCommaList
- asSeparatedList
- asSequence
- asSet
- at
- at0
- Bag
- clear
- collect
- dictionary
- difference
- excluding
- exists
- filterOnType
- first
- forAll
- foreach
- groupBy
- last
- includes
- includesAll
- including
- indexOf
- indexOf0
- insertAt
- intersection
- isEmpty
- notEmpty
- orderBy
- orderDescending
- prepend
- removeAt
- reject
- select
- sequence
- set
- size
- subSequence
- sum
- symmetricDifference
- union
- allInstances
- allInstancesAtTime
- allLoadedObjects
- allStates
- allSubClasses
- allSuperTypes
- associationEnds
- associationEndsWithType
- asString
- AsTaJson
- atTime
- attributes
- brokenConstraints
- canAccess
- constraints
- count
- emptyList
- existing
- externalId
- format
- let
- maxValue
- minValue
- nullValue
- objectfromExternalId
- oclAsType
- oclGetStates
- oclIsKindOf
- oclIsTypeOf
- random
- safeCast
- SoapCall
- superTypes
- taggedValue
- taggedValueOnFeature
- Translate
- typename
MDriven Turnkey
- CodeDress
- External login services in MDriven Turnkey
- Fonts
- Getting safe–limited–meta information from a Turnkey app
- How To Create a Dotnet MDriven Project
- How to Integrate Device Features in MDriven Apps Using the Navigator API
- Logging OCL in Turnkey
- Load balancing Turnkey and MDrivenServer
- MDriven on Synology
- Migrating From MDriven .NET Framework to .NET Core
- Office365 accesstoken
- Remote Turnkey access
- StartupViewTemplate
- SysDocBatch
- Use LibreOffice for PDF conversion
- Using Google Charts
- WPFMahappAndGantt
- AppWideAngularScriptIncludes
- AssetsTK
- Calling your own c - sharp .net things from Turnkey–server side
- Connecting javascript SinglePageApplications to Turnkey (SPA)
- DisplayWithVariables
- Geolocation
- Google Analytics in Turnkey app
- Google tag manager
- How to access your Turnkey site with FTP
- Javascript calling Turnkey rest
- Layout and CSS
- LiveUpdate
- MDriven turnkey Face - theme - styles - fashion
- MDriven Turnkey Series
- MDriven Turnkey theming
- Microsoft Azure
- Openid AzureAD
- OpenIdConnect access token and refresh token
- Overriding AngularJS MDriven Turnkey Views
- Pricing
- QR and barcode
- QR-Code to drive a workflow in any MDriven turnkey app
- Receive post data not known at design time
- Render data as html
- Render MVC ViewModel without turnkey
- Rendering the MDriven Turnkey application yourself
- Samples
- Scaling out Turnkey on Azure
- Serverside Turnkey and MVC functioning
- SiteAssets
- Size in Images in Turnkey
- Streaming Client
- SVG
- Theme and style
- Theme as data
- Time zones and sanity–post for future reference
- TinyMCE editor
- Tkusercss
- Turnkey App Current state: Paused
- Turnkey Client Timeout
- Turnkey debug
- Turnkey email settings
- Turnkey extra meta tags
- Turnkey local development tips
- Turnkey MVC Controllers
- Turnkey reload automatically on script change or style change
- Turnkey sample Board Map Balls Gantt
- Turnkey sample Empty start model
- Turnkey sample InstantPoll
- Turnkey sample ProjectPlanner
- Turnkey sample ProjectPlanning
- Turnkey sample SoftConflict
- Turnkey Styling
- TurnkeySettings
- TurnkeyUserLogin
- Use c-sharp code to post to TurnkeyRest
- View/Page override
- ViewMeta
MDriven Server
- Change password MDriven Server
- Corrupt MDriven Server
- Lost password or locked out
- MDriven Server problem with evolve
- MDrivenServer, opening the built-in database
- No suitable constructor found
- SQL not trusted
- The anti-forgery token could not be decrypted
- Troubleshooting Turnkey deployment
- Duplicate IDs in the database
- CodeFoundButOutOfSync
- AppPool user
- AsyncTicket
- Automating deployment of Turnkey and MDrivenServer on IIS
- CacheInvalidation
- Communication between MDrivenServers
- Deploy Turnkey on your own Azure with OneDrive
- Emailing from an app using MDrivenServer
- Eventlog
- Fill in the email settings in the admin UI
- HardServerUrl
- Injecting the Core server command line parameters via file
- Installation of MDriven Server on Windows 7 Enterprise
- LocalhostDevCert
- LocalServers
- MDriven administrative database tables
- MDrivenServer log
- MDrivenServer Slack web hook
- MDrivenServer with Windows authentication
- MDrivenServerOverride
- MultiTenantPrefix
- Purpose of History Server
- RecyclableMemoryStream
- Server Wide Variables
- Serverinfo
- Serverside actions
- Setting up a History slave
- Slave and History Server
- Slave server in action
- SysAsync package
- SysSingleton.Deflate
- SysSingleton.UrlEncode
- SysSingleton GetSystemUrl
- Turnkey and MDrivenServer logs
- Use SqlServer
- VistaDB
- WSL Windows subsystem for Linux
MDriven Framework
- Accessing objects and navigating meta-levels in code
- Api documentation
- Code generation
- Codegen Issues .net standard
- Constructor in generated code
- Debug CodeDress
- DisplayQueue
- Evolve db with code
- Side effects
- Unity 3D and MDriven
- Using different WCF Bindings with Enterprise Core Objects – ECO – MDriven framework
- HasUserCode in Enterprise Core Objects
- WinForms MDrivenFramework
- Working with legacy Handles
Legacy
Explore Documentation ⬇️
- Change tracking help SQL
- How your classes are stored in the SQL database when using MDriven
- Microsoft.data
- MySQL–notes to support the use of MySQL with MDriven
- Other PMappers
- Possible file version mismatch detected between ADO.NET Provider and native binaries of SQL Server Compact
- SQL Database
- SQL Server
- SQL Server change tracking
- SQLImport multiple tables with associations
- SQLite
- Versioned on class
- Authenticate with a jwt
- BankId
- Certificate
- External login screen problem
- Fault-finding certificate problems in IIS
- GDPRPolicy
- HashPassword
- HeaderBasedAuthenticationTag
- Hide External Login
- Hide Password login
- High or low exposure to risk
- How does OpenIdConnect work
- Lets encrypt
- OpenID config
- Sign client rest request with certificate
- AccessExpression
- Analyze ViewModel classes and expressions
- Breaking changes
- Cell level ReadOnly
- Comboboxes with strings
- Convergence
- Cursored or Full Tree
- Databind labels in ViewModels
- Databound Placeholder text
- Declarative ViewModels and Taborder
- Explaining “The ViewModel does not require a root object” warning
- How Null is represented in your picklist
- How to use vCurrent and “self” correctly in viewmodels
- Import xml and JSon with MDriven
- Index page
- Input Controls
- JsonToObject vs Tajson
- Multiple file upload component
- Opt out a constraint in all relevant viewmodel
- Per viewmodel ReadOnly mode
- QueryPlan
- RestAllowed UIAllowed
- SelfVM
- SOAP
- SOAP the protocol from the stone age
- Tables and Grids
- The combobox
- The VMClassId Explained
- Timedout viewmodel
- ViewModel access and security
- ViewModel for Business
OCLOperators nullValue
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Revision as of 21:05, 20 December 2023
This page was created by Alexandra on 2017-08-13. Last edited by Stephanie@mdriven.net on 2025-02-11.
A typed null value, used to assign a null value to an attribute, a variable or return null from a method.
someobject.someattribute := <Type>.nullValue
Do not use <Type>.nullValue to compare something to null, like this
vCurrent_UppdragTyp = Uppdragstyp.nullValue -- WRONG
For comparing to null, use the operators .isNull or .notNull