Exception parameters.grid [in template “template/jquery/gridcolumn.ftl”

问题

I am trying to make a grid by using Struts 2 jquery grid plugin along with struts jquery plugin and struts json plugin. I am beginner to this.

Here is my JSP code:

<s:form action="misinfo">
        <s:textfield name="sdate" label="START DATE"></s:textfield>
        <s:textfield name="edate" label="END DATE"></s:textfield>
        <s:submit value="submit"></s:submit>
        </s:form>
        <s:url var="remoteurl" action="jsontable" />
        <sjg:grid id="gridTable" caption="login ID" dataType="json"
            href="%{remoteurl}" pager="true" gridModel="gridModel"
            rowList="10,15,20" rowNum="15" rownumbers="true" />
        <sjg:gridColumn name="login ID"/>
        <sjg:gridColumn name="select" />

struts.xml

<package name="mypackage" namespace="/" extends="struts-default, json-default">
     <result-types>
            <result-type name="json" class="org.apache.struts2.json.JSONResult" default="true"/>
            <result-type name="dispatcher" class="org.apache.struts2.dispatcher.ServletDispatcherResult" default="true"/>
        </result-types>
<action name="mis" class="com.action.JsonAction">
        <result name="success">/WEB-INF/jsp/mis.jsp</result>
        <result name="input">/WEB-INF/jsp/mis.jsp</result>
        </action>
        <action name="jsontable" class="com.action.JsonAction">
        <result name="success">/WEB-INF/jsp/mis.jsp</result>
        </action>
</package>

Action class

public class JsonAction extends ActionSupport {
    private String gridModel;
    private int rows = 0;
    private int page = 0;
    private String sortAsc;
    private String sortIndex;
    private String searchField;
    private String searchOprtn;
    private int total = 0;
    private int records = 0;

    @Override
    public String execute() throws Exception {

        int to = (rows * page);
        int from = to - rows;
        JsonActionDao jsn = new JsonActionDaoImpl();
        records = jsn.getNoOfRecords();
        gridModel = jsn.getRecords();
        total = (int) Math.ceil((double) records / (double) rows);
        System.out.println("row "+rows+"page "+page+"gridModel "+gridModel);
        return "success";
      // getter and setter for fields.,,,....
    }
}

Exception that I am getting

The following has evaluated to null or missing:
==> parameters.grid  [in template "template/jquery/gridcolumn.ftl" at line 22, column 29]

----
Tip: It's the step after the last dot that caused this error, not those before it.
----
Tip: If the failing expression is known to be legally refer to something that's null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----

----
FTL stack trace ("~" means nesting-related):
    - Failed at: ${parameters.grid?string?replace(".",...  [in template "template/jquery/gridcolumn.ftl" at line 22, column 27]
    - Reached through: #assign escapedOptionId = "\${paramet...  [in template "template/jquery/gridcolumn.ftl" at line 22, column 1]
----

Java stack trace (for programmers):
----
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]

回答1:

The grid tag shouldn't be self-closed, it should have a body where you put gridCoumn tags.

The name of the column should be a property of the gridModel, and as a bean's property must be an identifier, i.e. without spaces.

Grid model should be a list of objects that a reserialized to JSON via invoking an action that you use in href attribute.

<sjg:grid id="gridTable" caption="login ID" dataType="json"
    href="%{remoteurl}" pager="true" gridModel="gridModel"
    rowList="10,15,20" rowNum="15" rownumbers="true">
      <sjg:gridColumn name="loginID"/>
      <sjg:gridColumn name="select" />
</sjg:grid>

You can find an example of the grid using the project wiki page for Grid Tag.

来源：https://stackoverflow.com/questions/38320028/exception-parameters-grid-in-template-template-jquery-gridcolumn-ftl