[Solved] Why should I use ModelLink instead of just autocomplete component?

Use One.form.ModelLinkField (xtype: 'modellinkfield') for screens or MODEL_LINK field type in reports.
It makes user experiences seamless across all UI and gives ability to:

• select multiple models in picker
• search with wild-card
• force user to select a value from picker/autocomplete or just give a wild card

Please check short example below for a report, where both wild-card and exact user selection are supported. Single sql-based report is used for user selection in picker and autocomplete. In retrieval section duet o model link field type usage platform will automatically generate a registered drill down link from report to user details.

<Report>
  <Name>SearchUsers</Name>
  <SqlDef Name="SearchUsers" GroupName="Reports"><![CDATA[
  select sys_user_id, user_name from users 
  where ${filterIfNotNull:SYS_USER_ID,sys_user_id in $SYS_USER_ID$}
    and ${filterIfNotNull:USER_NAME,${reverseUpperLeadingWildcard:user_name,$USER_NAME$}}
  ]]></SqlDef>
  <Filters>
      <CustomFilterField>
        <FieldRef levelType="Undefined" category="MODEL_LINK">
          <ModelLinkTargetLevelType>User</ModelLinkTargetLevelType>
          <FieldName>UserName</FieldName>
        </FieldRef>
        <Type>MODEL_LINK</Type>
        <ModelLinkHandling>
          <CustomModelName/>
          <PickerReportDefName>OMS.UserPickerReport</PickerReportDefName>
          <AutocompleteReportBased>true</AutocompleteReportBased>
        </ModelLinkHandling>
        <ModelLinkMapping exactMode="false" surrogateIdSqlName="SYS_USER_ID" displayFieldSqlName="USER_NAME" multiSelectMode="false"/>
      </CustomFilterField>
    </Filters>
  <Retrievals>
    <CustomRetrievalField>
      <FieldRef levelType="User" category="PDF">
        <ModelLinkTargetLevelType>User</ModelLinkTargetLevelType>
        <FieldName>Name</FieldName>
      </FieldRef>
      <Type>MODEL_LINK</Type>
      <ModelLinkMapping surrogateIdSqlName="SYS_USER_ID" displayFieldSqlName="USER_NAME"/>
    </CustomRetrievalField>
  </Retrievals>
</Report>