Select (attribute of foreach)

From JRapid

The "foreach" element is useful when you have an entity A which specifies an embedded inline collection property of an entity B and you want that collection to be automatically loaded with elements of an entity C.

A first approach to solve this requirement will be overriding the find() method of the entity A. The new find() method can query all the C elements and then for each element of the entity C, create a new element B to hold that element. Finally, return the entity A with the collection of B elements.

JRapid's "foreach" does the same job. You only need to provide an EL expression for querying all the C elements and specify which is the property of the B entity which will hold each element.

The "foreach" element is specified inside the property which is an embedded inline collection.

Usage

<foreach 
         select = SELECT
         setproperty = PROPERTY
         property = PROPERTY
/>

1. select: EL expression for getting the collection of elements to be added.
2. setproperty: the property of the embedded inline entity for storing the items of the collection returned by the select expression.
3. property: only applicable when the foreach is inside a subset. It indicates the properties where it will be applied.

Examples

• Loading a company's additional data fields:

//Entity A
<entity label="Company" name="Company">
   ...
   <property childproperty="company" collection="sortedset" embedded="inline"
      entity="DataValue" label="Additional Info" labelposition="top" name="additionalData"
      setorder="data">
      <foreach select="Data:findAll()" setproperty="data"/>
   </property>
   ...
</entity>

//Entity B
<entity label="AdditionalInfoRow" name="AdditionalInfoRow">
   <property entity="Company" label="Empresa" name="company"/> //Connects entity A with B
   <property display="primary" entity="Data" label="Data" name="data"/> //Connects entity B with C
   <property display="secondary" label="Value" name="value"/>
</entity>

//Entity C
<entity label="Data" name="Data">
   <property display="primary" label="Data" name="data"/>
</entity>

Generated find() method in CompanyServicesAbstract.java:

    // code for find
    public Company find(String id) throws ELException {
        Company obj = null;
        
        // step 1: build map
        ExpressionVariableResolver evr = new ExpressionVariableResolver();
        FunctionMapper fm = new FunctionMapper();
        Session session = Session.getMySession();
            
        if (id.equals("0")) {    
            // step 2: new object
            obj = new Company();
            
            // step 3: setvalues               
            obj.setComments((String)el.evaluate("${'Comments for this company...'}",
            String.class, evr, fm));
        } else {
            obj = Company.DAO().findById(id);
        }
        
        // step 4: locking
        long time = new java.util.Date().getTime();
        
        obj.setReadLastUser(session.getUsername());
        obj.setReadTimestamp(time);
        
        // step 5: foreach
        for (Object o:((Iterable)el.evaluate("${Data:findAll()}", Object.class, evr, fm))) {
            if (!obj.containsAdditionalData(o)) {
                DataValue newObject = new DataValue();
                newObject.setData((Data)o);
                newObject.setCompany(obj);
                obj.getAdditionalData().add(newObject);
            }
        }
          
        // step 6: return
        return obj;
    }

• DailyCurrenyRates example:

    <entity label="Currency" name="Currency">
        <property display="primary" label="Name" name="name"/>
    </entity>

    <entity label="CurrencyValue" name="CurrencyValue">
        <property entity="Currency" fixed="fixed" label="Currency"
          name="currency"/>
        <property label="Value" name="value" type="double"/>
        <property entity="DailyCurrencyRates" label="Daily Currency Rates"
          name="dailyCurrencyRates"/>
    </entity>

    <entity label="Daily Currency Rates" name="DailyCurrencyRates">
        <property default="now" label="Date" name="rateDate" type="date"/>
        <property childproperty="dailyCurrencyRates" collection="sortedset"
         embedded="inline" entity="CurrencyValue" label="Values" 
         labelposition="fieldset" name="currencyValues" setorder="currency">
            <foreach select="Currency:findAll()" setproperty="currency"/>
        </property>
    </entity> 

See also

• Related article: The for each element
• embedded
• dynamicforeach