CAML Query when using Or fails giving "Cannot complete this action"

Question

I am creating an SPFX web part which queries a list in SharePoint Online

This works fine:

camlQuery = "<Query><OrderBy><FieldRef Name='LinkTitle' Ascending='TRUE' /></OrderBy></Query>"

It brings back all values from the list.

However if I try to just bring back certain rows:

camlQuery = "<View><Query><Where>";

        camlQuery += "<Or>";
        camlQuery += "<Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>bloggsj</Value></Eq>";
        camlQuery += "<Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>bloggsa</Value></Eq>";
        camlQuery += "<Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>bloggsb</Value></Eq>";

        camlQuery += "</Or>";
        
        camlQuery += "</Where></Query></View>";

I get the error:

Error making HttpClient request in queryable [500] Internal Server Error ::> {"odata.error":{"code":"-2147467259, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"Cannot complete this action.\n\nPlease try again."}}}

Answer 1

Use CAML query in this format:

<View>
    <Query>
        <Where>
            <Or>
                <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>bloggsj</Value></Eq>
                <Or>
                    <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>bloggsa</Value></Eq>
                    <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>bloggsb</Value></Eq>
                </Or>
            </Or>
        </Where>
    </Query>
</View>

Note

The Or element can be nested inside other Or and And elements. The server supports unlimited complicated queries. However, any given Or element can have only two child elements. If you need to join three or more conditions, you must nest the Or elements.

Documentation: Or element (Query)

Update from comments:

You can write CAML query in below format for 6 users:

<View>
    <Query>
        <Where>
            <Or>
                <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>user1</Value></Eq>
                <Or>
                    <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>user2</Value></Eq>
                    <Or>    
                        <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>user3</Value></Eq>
                        <Or>    
                            <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>user4</Value></Eq>
                            <Or>    
                                <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>user5</Value></Eq>
                                <Eq><FieldRef Name='onPremisesSamAccountName'></FieldRef><Value Type='Text'>user6</Value></Eq>
                            </Or>
                        </Or>
                    </Or>
                </Or>
            </Or>
        </Where>
    </Query>
</View>