MICROSOFT DYNAMICS 365: Query Expression Add Criteria for look up field (Dynamics 365

Microsoft Dynamics 365 Plugin C# code.

If you wanna retrieve multiple records, you may use RetrieveMultiple function.

You can set filters and select the columns(fields) in the retrieve response.

When I set a filter for a lookup field (GUID), I tried two ways.

Both options work normally, the second way is better, greatly reduced the Amount of retrieved records, better for system performance. But the first way is still a good try for reading and comparing GUID value from retrieve response.

Option 1: Add filter in retrieve result procession. (Bad performance.)

// Retrieve all tasks with regarding opportunity is current opportunity

var queryExpression = new QueryExpression(kidEntity);

var qeFilter = new FilterExpression(LogicalOperator.And);

qeFilter.AddCondition(new ConditionExpression("statecode", ConditionOperator.Equal, "Open"));

qeFilter.AddCondition(new ConditionExpression("subject", ConditionOperator.Like, "%F/U%"));

qeFilter.AddCondition(new ConditionExpression("description", ConditionOperator.Like, "%Automated Task%"));

queryExpression.Criteria = qeFilter;

queryExpression.ColumnSet = new ColumnSet("regardingobjectid");

//Get results:

var result = service.RetrieveMultiple(queryExpression);

foreach (var relatedTask in result.Entities)

{

if(((EntityReference)relatedTask.Attributes["regardingobjectid"]).Id.ToString() == (regardingobjectid).ToString())

{

// Create the Request Object

var state = new SetStateRequest();

state.State = new OptionSetValue(stateCode);

// Point the Request to the case whose state is being changed

state.EntityMoniker = new EntityReference(kidEntity, relatedTask.Id);

// Execute the Request

var stateSet = (SetStateResponse)service.Execute(state);

}

Option 2: Add the filter into the query expression criteria. (Good performance.)