View source for WpclsQueryDetailsInfo

{{DISPLAYTITLE:wpclsQueryDetailsInfo}}
This method is called to allow the class object to specify its details to be used for its instances.

==Syntax==
<pre>
ULONG _wpclsQueryDetailsInfo(M_WPObject *somSelf, PCLASSFIELDINFO pClassFieldInfo, PULONG pSize)
</pre>

==Parameters==
;''somSelf'' ([[M_WPObject *]]) - input
:Pointer to the [[WPObject]] class object.

;''pClassFieldInfo'' ([[PCLASSFIELDINFO]]) - in/out
:Pointer to details information.

;''pSize'' ([[PULONG]]) - in/out
:Total number of bytes of details data. This total includes the details added by this class and ancestor classes.

==Returns==
;''ulReturn'' ([[ULONG]]) - returns
:Sum of the number of detail columns for the object. This sum includes details added by this class and ancestor classes.

==Remarks==
All objects which have information to display in details view must override this method. The two possible queries are:

**Query 1**
A request for the [[CLASSFIELDINFO]] linked list segment associated with an object. This information is needed just prior to changing the view of a container control to details view.

If **pClassFieldInfo** is `NULL` (no subclasses have appended details data), the number of columns of details information for this class and all its superclasses is returned. If **pClassFieldInfo** is `NON-NULL`, the number of columns of details information is returned and ***pClassFieldInfo** points to the head of a linked list of [[CLASSFIELDINFO]] structures to which a linked list of [[CLASSFIELDINFO]] structures describing the details fields of objects of this subclass should be appended.

For example, on input ***pClassFieldInfo**:
<pre>
CLASSFIELDINFO_1_grandparent
CLASSFIELDINFO_2_grandparent
  CLASSFIELDINFO_1_parent
</pre>

On output, ***pClassFieldInfo**:
<pre>
CLASSFIELDINFO_1_grandparent
CLASSFIELDINFO_2_grandparent
  CLASSFIELDINFO_1_parent
CLASSFIELDINFO_1_self
</pre>

The correct way to handle this request is to do the following:
* Call the parent method. The parent method returns the number of columns the ancestors have contributed.
* Walk the chain of [[CLASSFIELDINFO]] structures to the end and append the chain of [[CLASSFIELDINFO]] structures for the current class (using the **pNextFieldInfo** element).
* If ***pClassFieldInfo** is zero (indicating no parent columns), assign ***pClassFieldInfo** = beginning of [[CLASSFIELDINFO]] chain for this subclass.
* Return the sum of the details columns of the parent and the current subclass.

Note the following differences between the [[CLASSFIELDINFO]] and [[FIELDINFO]] structures:
* The **offFieldData** and **ulLenFieldData** fields are required so that appropriate offsets for the data can be computed. The application is responsible for providing **offFieldData** and **ulLenFieldData** fields.
* The **ulReserved** field should be left `NULL`.
* Owner draw, comparison, and sort functions may be specified for the field.

For example, if an object has three fields:
<pre>
typedef struct _SAMPLE_DETAIL_DATA {
  CDATE   cdate;
  CTIME   ctime;
  PSZ     psz;
}  SAMPLE_DETAIL_DATA;

classfieldinfo[0].offFieldData   = FIELDOFFSET(SAMPLE,cdate);
classfieldinfo[0].ulLenFieldData = FIELDOFFSET(SAMPLE,ctime)
                                     FIELDOFFSET(SAMPLE,cdate);

classfieldinfo[1].offFieldData   = FIELDOFFSET(SAMPLE,ctime);
classfieldinfo[1].ulLenFieldData = FIELDOFFSET(SAMPLE,psz) -
                                     FIELDOFFSET(SAMPLE,ctime);

classfieldinfo[2].offFieldData   = FIELDOFFSET(SAMPLE,psz);
classfieldinfo[2].ulLenFieldData = sizeof(SAMPLE) -
                                     FIELDOFFSET(SAMPLE,psz);
</pre>

Note that ***pClassFieldInfo** must be modified to point to the beginning of the [[CLASSFIELDINFO]] linked list only if ***pClassFieldInfo** is `0`. The application must return the sum of the details columns of the parent and itself:
<pre>
return(n_cols + n_parent_cols);
</pre>

Note also that the fields MUST be set up sequentially. `classfieldinfo[0]` must point to data at an offset of `0`. `classfieldinfo[n]` must point to data adjacent, and directly following that described by `classfieldinfo[-1]`.

**Query 2**
The number of bytes of details data associated with an object. This information is needed prior to allocating memory for a container control insert record.

If **pSize** is `NON-NULL`, the override should adjust ***pSize** by the number of bytes which must be added to the end of a [[MINIRECORDCORE]] structure to hold the details information for objects of this class.

Example:
<pre>
*pSize += bytes_of_details_data;
</pre>

In the case of the above example,
<pre>
*pSize += sizeof(SAMPLE_DETAIL_DATA);
</pre>

**Note:** All class field pointers returned should be pointers to static data areas.

==How to Override==
This method should be overridden by classes that introduce class-specific details to be displayed in details view. The parent method must always be called before appending the request information.

==Usage==
This method is generally called only by the system.

==Example Code==
This example adds details data for the Car object by appending `FIELDINFO` structures to `*ppClassFieldInfo`.
<pre>
SOM_Scope ULONG SOMLINK carM_wpclsQueryDetailsInfo(M_Car *somSelf,
                                  PCLASSFIELDINFO *ppClassFieldInfo,
                                  PULONG pSize)
{
  ULONG           cParentCol;
  PCLASSFIELDINFO pCFI;
  ULONG           i;

    /* M_CarData *somThis = M_CarGetData(somSelf); */
    M_CarMethodDebug("M_Car","carM_wpclsQueryDetailsInfo");

   /* Always call the parent method first to retrieve the number of
       details columns and any data already defined in the details buffer. */

   cParentCol = parent_wpclsQueryDetailsInfo(somSelf, ppClassFieldInfo, pSize);

       /* If details columns exist, add the size of ours to it */

   if (pSize)
       *pSize += sizeof(CARDETAILS);

   /* If the request was for the chained fieldinfo structures
    * (ppClassFieldInfo is non-NULL), link them in
    *
    * eventually the chain will look like
    *
    * Grandad - Dad - Me - Kid - Grandkid
    *
    * I will be getting the pointer to the beginning of the chain
    *
    * If the beginning of the chain is 0, I will assign the address
    * of my first CLASSFIELDINFO structure to *ppClassFieldInfo.
    * Otherwise *pp points to the first column description in the
    * chain.  We need to walk the chain and link our CLASSFIELDINFO
    * structures at the end.
    */

   if (ppClassFieldInfo) {

       if (*ppClassFieldInfo) {
         pCFI = *ppClassFieldInfo;
         for (i=0;i<cParentColumns;i++)
             pCFI = (pCFI->pNextFieldInfo) ? pCFI->pNextFieldInfo : pCFI;

         pCFI->pNextFieldInfo = fieldinfo;
       } else {
         *ppClassFieldInfo = fieldinfo;
       } /* endif */

   } /* endif */

   return ((ULONG) (cParentColumns + NUM_CAR_FIELDS));
}
</pre>

==Related Methods==
* [[wpQueryDetailsData]]
* [[wpclsQueryDetails]]
* [[wpclsQueryDetailsInfo]]

[[Category:Workplace Class Methods]]