Updating managed metadata field in sharepoint online document library using SPFx

Question

I need to update the some columns(EmpId,DocumentDate,PRType,Commnunity) in my document library.Out of which PRType & Community is managed metadata column. All works file and updated when I update only EmpId & DocumentDate, but as soon as I added "PRType":{'label':'TermName','TermGuid':'GUID of Term','WssId':-1} & Community in my metadata to update it gives 400 error. So metadata column not updated, where I went wrong in updating the metadata column.

   var fileUrl=`https://xxxxx.sharepoint.com/sites/TestSite/_api/Web/Lists/getByTitle('Drop%20Off%20Library')/Items(id)`;
 
   const body = {
    '__metadata': { 'type': 'SP.Data.DropOffLibraryItem' }, "EmpId": "021345","DocumentDate":"Date"
    ,"PRType":{'label':'TermName','TermGuid':'GUID of Term','WssId':-1}
    ,"Community":{'label':'TermName','TermGuid':'GUID of Term','WssId':-1}
};
   
   let spOpts1 : ISPHttpClientOptions  = {
    headers: {
        'IF-MATCH': '*',
        'Content-type': 'application/json;odata=verbose',
        "accept": "application/json;odata=verbose",
        "odata-version":"3.0",
        'X-HTTP-Method': 'MERGE'
    },
    body: JSON.stringify(body)       
  };
   
   this.props.context.spHttpClient.post(fileUrl,SPHttpClient.configurations.v1,spOpts1).then((response: SPHttpClientResponse) => {
    alert(response.status + ':' + response.ok);        
        }) 
    }```

Answer 1

let requestUrl = this.context.pageContext.web.absoluteUrl.concat(“/_api/web/lists/getbytitle(‘YourListTitle’)/items(ListItemId)”);   

let dataToPost = JSON.stringify({   

    ‘__metadata’: {   

        ‘type’: ‘SP.Data.YourListTitleListItem’   

    },   

    “TermFieldSingle”:{ 

        “Label”:”Test Value 1″, 

        “TermGuid”:”GUID of the Term”, 

        “WssId”:-1 //which make sure to create an entry in TaxonomyHiddenList if not added. 

        }  

});   

let spOpts = {   

    headers: { 

        ‘Accept’: ‘application/json;odata=nometadata’, 

        ‘Content-type’: ‘application/json;odata=verbose’, 

        ‘odata-version’: ”, 

        ‘IF-MATCH’: ‘*’, 

        ‘X-HTTP-Method’: ‘MERGE’ 

    }, 

    body: dataToPost   

};   

this.context.spHttpClient.post(requestUrl, SPHttpClient.configurations.v1, spOpts).then((response: SPHttpClientResponse) => {   

    if (response.ok) {   

        response.json().then((responseJSON) => {   

            console.log(responseJSON);   

        });   

    }   

});   

Try this!