sharepoint 2013 how to update managed metadata field (TaxonomyFieldType) using soap API

Question

I am trying to update managed metadata field (TaxonomyFieldType) using SOAP API following is my SOAP XML

<Batch OnError = "Continue">
    <Method ID = "1" Cmd = "Update">
        <Field
            Name = "ID"
            xsi:type = "xsd:string"
            xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
            xmlns:xsd = "http://www.w3.org/2001/XMLSchema">12</Field>
        <Field
            Name = "TaskOutcome"
            xsi:type = "xsd:string"
            xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
            xmlns:xsd = "http://www.w3.org/2001/XMLSchema">Approved</Field>
        <Field
            Name = "Title"
            xsi:type = "xsd:string"
            xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
            xmlns:xsd = "http://www.w3.org/2001/XMLSchema">sample</Field>
        <Field
            Name = "FileRef"
            xsi:type = "xsd:string"
            xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
            xmlns:xsd = "http://www.w3.org/2001/XMLSchema">sample.txt</Field>
        <Field
            Name = "MM"
            DisplayName = "MM_0"
            Type = "TaxonomyFieldTypeMulti"
            xsi:type = "xsd:string"
            xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
            xmlns:xsd = "http://www.w3.org/2001/XMLSchema">-1;#test2|168baffc-6f72-46cd-8750-98d53ed1acca</Field>
    </Method>
</Batch>

There is no error from the server and managed metadata filed not getting updated.

Could you please help me that i am doing somethink wrong here...

Answer 1

When you add Managed metadata field in SharePoint with Note fieldType It will add a hidden field with field type Note and Non-hidden field with field type as TaxonomyFieldTypeMulti or TaxonomyFieldType

<Field
       Name = "MM"
        DisplayName = "MM_0"
        Type = "TaxonomyFieldTypeMulti"
        xsi:type = "xsd:string"
        xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
        xmlns:xsd = "http://www.w3.org/2001/XMLSchema">-1;#test2|168baffc-6f72-46cd-8750-98d53ed1acca</Field>

Instead of updating the above field you need to update its hidden Note field type with DisplayName = "MM_0" and Name = "Some Id"

<Field
        Name = "of525fec62a44747aa623e3c49dac9e8"
        DisplayName = "MM_0"
        Type = "Note"
        xsi:type = "xsd:string"
        xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
        xmlns:xsd = "http://www.w3.org/2001/XMLSchema">test2|168baffc-6f72-46cd-8750-98d53ed1acca</Field>

In SOAP your request should be like this below

<Method Cmd="Update" ID="1">
  <Field Name="ID">12</Field>
  <Field Name="Title">Sample</Field>
  <Field Name="of525fec62a44747aa623e3c49dac9e8">test2|168baffc-6f72-46cd-8750-98d53ed1acca</Field>
</Method>

If you used the schema generate schema with the hidden field type as Note You will get schema with "Name="of525fec62a44747aa623e3c49dac9e8" you can easily update that value.

Sharpoint return as Note fieldType as

<Field Type="Note" DisplayName="MM_0" StaticName="of525fec62a44747aa623e3c49dac9e8" 
 Name="of525fec62a44747aa623e3c49dac9e8" 
 ID="{6DDB9ADF-BC5E-4D07-BE70-F450A24C7520}" ShowInViewForms="FALSE" Required="FALSE" 
 CanToggleHidden="TRUE"  Hidden="TRUE"/>

I hope the above explanation will solve your issue !!!