调用webapi接口保存单据时使用id为维度关联字段赋值

在调用webapi的保存接口时，想通过id为维度关联字段赋值，试了好久没赋值成功。维度关联字段该怎么赋值？
json字符串如下：
[code]

{
"formid": "PBMQ_PDA_TEST",
"data": {
"Creator": "",
"NeedUpDateFields": [],
"NumberSearch": false,
"Model": {
"FID": "0",
"FBillNo": "",
"FbillTypeID": "PBMQ_PDA_TEST",

//物料字段
"F_PBMQ_Base": {
"FMATERIALID": 370777
},
"F_PBMQ_Base1": {
"FCUSTID": 374581
},
"F_PBMQ_UnitID": {
"funitid": 100398
},

//物料关联的辅助属性字段，就是需要赋值的字段
"FAuxPropId": {
"FF100001": {
"fylmxid": 221120
},
"FF100002": {
"ftrdbshid": 317696
},
"FF100003": null,
"FF100004": {
"fskshid": 426388
},
"FF100005": {
"fysid": 227120
},
"FF100006": null,
"FOPCODE": null
},
"FStockID": {
"FStockID": 444615
},

//仓位辅助属性字段，也是需要赋值的字段
"FSPID": {
"FF100004": {
"fid": "1.002"
},
"FF101001": null,
"FF101002": null,
"FF101003": null,
"FF101004": null,
"FF101501": null,
"FF101507": null,
"FF101509": null,
"FF102001": null,
"FF102002": null,
"FOPCODE": null
}
}
}
}

[/code]