[seam-issues] [JBoss JIRA] Updated: (SEAMFACES-141) Create a converter for dealing with lists

[Brian Leathem (JIRA)]

     [ https://issues.jboss.org/browse/SEAMFACES-141?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Brian Leathem updated SEAMFACES-141:
------------------------------------

    Description: 
A converter is required to serialize an object into the query string for use as a view param.  If that object is a list, it would be helpful to make use of an existing converter that converts each individual entry, and has the cumulative result serialized as a string.

The standard CGI syntax represents arrays as multiple values, each with the same key.  This may already be supported in JSF, but at the time of writing this, I couldn't find it.

Possible implementation (not conformant with the above mentioned CDI standard syntax:
{code}
abstract public class ListConverter<T> implements Converter {
    private final Converter converter;
    private final String SEPERATOR_CHAR=":";

    public ListConverter(Converter converter) {
        this.converter = converter;
    }
    
    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        List<T> newList = new ArrayList<T>();
        if (value == null || value.isEmpty()) {
            return newList;
        }
        String[] chunkArray;
        if (value.startsWith("[")) {
            String chunks = value.substring(1, value.length()-1);
            chunkArray = chunks.split(SEPERATOR_CHAR);
        } else {
            chunkArray = new String[] {value};
        }
        for (String chunk : chunkArray) {
            try {
                Object object = converter.getAsObject(context, component, chunk);
                newList.add((T) object);
            } catch (IllegalArgumentException e) {
                FacesMessage facesMessage = new FacesMessage(FacesMessage.SEVERITY_ERROR, String.format("%s is not a valid search term",value), null);
                context.addMessage(null, facesMessage);
            }
        }
        return newList;
    }
    
    @Override
    public String getAsString(FacesContext context, UIComponent component, Object value) {
        if (value instanceof List) {
            List<T> conversionList = (List<T>) value;
            if (conversionList.isEmpty()) {
                return "";
            }
            StringBuilder sb = new StringBuilder();
            sb.append("[");
            for (int i=0; i < conversionList.size(); i++ ) {
                String string = converter.getAsString(context, component, conversionList.get(i));
                sb.append(string);
                if (i < conversionList.size() -1) {
                    sb.append(SEPERATOR_CHAR);
                }
            }
            sb.append("]");
            return sb.toString();
        } else {
            throw new IllegalArgumentException(String.format("Cannot convert object of class %s", value.getClass().getName()));
        }
    }
}
{code}

  was:
A converter is required to serialize an object into the query string for use as a view param.  If that object is a list, it would be helpful to make use of an existing converter that converts each individual entry, and has the cumulative result serialized as a string.

The standard CGI syntax represents arrays as multiple values, each with the same key.  This may already be supported in JSF, but at the time of writing this, I couldn't find it.



> Create a converter for dealing with lists
> -----------------------------------------
>
>                 Key: SEAMFACES-141
>                 URL: https://issues.jboss.org/browse/SEAMFACES-141
>             Project: Seam Faces
>          Issue Type: Feature Request
>          Components: Validation & Conversion
>            Reporter: Brian Leathem
>
> A converter is required to serialize an object into the query string for use as a view param.  If that object is a list, it would be helpful to make use of an existing converter that converts each individual entry, and has the cumulative result serialized as a string.
> The standard CGI syntax represents arrays as multiple values, each with the same key.  This may already be supported in JSF, but at the time of writing this, I couldn't find it.
> Possible implementation (not conformant with the above mentioned CDI standard syntax:
> {code}
> abstract public class ListConverter<T> implements Converter {
>     private final Converter converter;
>     private final String SEPERATOR_CHAR=":";
>     public ListConverter(Converter converter) {
>         this.converter = converter;
>     }
>     
>     @Override
>     public Object getAsObject(FacesContext context, UIComponent component, String value) {
>         List<T> newList = new ArrayList<T>();
>         if (value == null || value.isEmpty()) {
>             return newList;
>         }
>         String[] chunkArray;
>         if (value.startsWith("[")) {
>             String chunks = value.substring(1, value.length()-1);
>             chunkArray = chunks.split(SEPERATOR_CHAR);
>         } else {
>             chunkArray = new String[] {value};
>         }
>         for (String chunk : chunkArray) {
>             try {
>                 Object object = converter.getAsObject(context, component, chunk);
>                 newList.add((T) object);
>             } catch (IllegalArgumentException e) {
>                 FacesMessage facesMessage = new FacesMessage(FacesMessage.SEVERITY_ERROR, String.format("%s is not a valid search term",value), null);
>                 context.addMessage(null, facesMessage);
>             }
>         }
>         return newList;
>     }
>     
>     @Override
>     public String getAsString(FacesContext context, UIComponent component, Object value) {
>         if (value instanceof List) {
>             List<T> conversionList = (List<T>) value;
>             if (conversionList.isEmpty()) {
>                 return "";
>             }
>             StringBuilder sb = new StringBuilder();
>             sb.append("[");
>             for (int i=0; i < conversionList.size(); i++ ) {
>                 String string = converter.getAsString(context, component, conversionList.get(i));
>                 sb.append(string);
>                 if (i < conversionList.size() -1) {
>                     sb.append(SEPERATOR_CHAR);
>                 }
>             }
>             sb.append("]");
>             return sb.toString();
>         } else {
>             throw new IllegalArgumentException(String.format("Cannot convert object of class %s", value.getClass().getName()));
>         }
>     }
> }
> {code}

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