list
in the datamodel, and in this list create fields
that represent the properties of the entity.Data model-tab
, you get to all the data model functionalities. You will also see a menu with several options:New list
, you get a popup where you can enter the following:Name
: this is the name you want to give the list. It must be a unique name;Technical name
: the technical name is an automatically generated field. This is the name WEM uses to reference this field. You will see this name when you are, for example, using expressions where you need to access this field. List type
: You can choose whether you want a transient list
or a database list
. The rows of a database list are stored in the database of the project. The data in a transient list have the lifetime of the client session. Save
button and the list is created.ID
: this is the unique identifier for a row in a list. This field is required and cannot be changed;Last modified
: this field contains the date of when a specific row is last modified. As with the ÃŒD
field, you cannot change or delete the Last modified
field.New field
pop-up window. You can now select the type of field you want to add. The list is the same as the data types mentioned above. After you have selected the type of field you need, you get a popup where you can add additional information that is needed for the field.Name
: The name you want to give a field;Technical name
: The technical name that WEM uses throughout the Modeler;Save this field to the database
: This checkbox is checked by default. In some cases you may want a field that you want to use temporarily so no data needs to be stored. But normally this box is always checked;Default value
: the default value that you want to give this field every time e new row for a list is added.Text field
Validation
: A number of pre-defined validation rules can be applied. For example when the validation e-mail
is used, WEM checks whether the entered value is a correct email address;Max length
: The maximum number of characters that can be stored in this field;Numeric
Minimum value
: this is the minimum value this Numeric field will accept;Maximum value
: the maximum value this Numeric field will accept;File
Validation
: Allows you to select one (1) file-type that is allowed for this field. So if you want to store, let's say, only pdf files, you can specify that here;Maximum file size
: if the file that is stored can only have a maximum size, then you can specify that here. The file size is specified in kilobytes;Allow access when
: this is where you can restrict access to this field. You can define the access rule using the expression editor. This field is required when you create a File
field, and should be put to True
when used without any constraints;Single select
& Multi select
Root concept
: you need to specify which concept you want to use for the single select field. Check the Ontology/Concept section for more information on 'concepts';Depth
: if a concept has multiple levels, you have the possibility to specify whether you only want to be able to select the direct children of the concept, or the children of all levels of this concept. Again, check the Ontology/Concept section for more information on 'concepts';Only concepts with type
: you can restrict the available concepts to concepts that have a specific type. Do this by selecting the particular type you're interested in;Reference
Referenced list
: a reference field refers to another list, so obviously you need to specify to which list this field is refering. Simply click on the button on the right-hand side of the field and a selection pop-up appears that enables you to select the list that that needs to be referenced to.Edit
is used to change the properties of a field or list. To edit a field: select the field/list and click the edit
button;Move
is used to move a field/list to another list or folder . When a field/list is selected and move
is selected, a popup appears where you can select the destination of the field/list;Delete
is straightforward, thus will delete the field or list you have selected. When you do this, all data that is stored in the database will also be deleted. Calculated field
to a list. A calculated field is a field that contains a value that is calculated. When you add a calculated field, the calculation needs to result in a data type that is the same as the data type of the calculated field. The calculation itself is defined using a WEM expression.Name
: The name you want to give a field;Technical name
: The technical name WEM uses throughout the Modeler;Type
: The type that the expressions should yield as result (only available when creating a new calculated field);Calculated value
: this is where you enter the expression that specifies the calculation.Find usages
button provides very useful information: it shows where the selected element is used in your application. When you need to change something or delete a field, you need to know where it is used. This is a simple way to find out whether that is possible, and even better, it allows you to go to the locations where an item is used if you want to change or delete it.