spservices.js.Error:- Uncaught (in > promise) TypeError: Cannot read properties of undefined (reading > 'LookupList')

Question

Inside our SPFx web part we have the following code inside the spservices.js code:-

spservices.prototype.getLookupFieldOptions = function (siteUrl, listId, fieldInternalName) {  
        return __awaiter(this, void 0, void 0, function () {  
            var fieldOptions, web, results, options, _i, options_1, option, error_14;  
            return __generator(this, function (_a) {  
                switch (_a.label) {  
                    case 0:  
                        fieldOptions = [];  
                        _a.label = 1;  
                    case 1:  
                        _a.trys.push([1, 5, , 6]);  
                        web = new Web(siteUrl);  
                        return [4 /*yield*/, web.lists.getById(listId)  
                                .fields.usingCaching()  
                                .filter("InternalName eq '" + fieldInternalName + "'")  
                                .select("LookupList", "LookupWebId", "LookupField")  
                                .top(1)  
                                .get()];  
                    case 2:  
                        results = _a.sent();  
                        if (!results) return [3 /*break*/, 4];  
                        return [4 /*yield*/, web.lists.getById(results[0].LookupList)  
                                .items.usingCaching()  
                                .select("ID", results[0].LookupField)  
                                .getAll()];  
                    case 3:  
                        options = _a.sent();  
                        if (options && options.length > 0) {  
                            for (_i = 0, options_1 = options; _i < options_1.length; _i++) {  
                                option = options_1[_i];  
                                fieldOptions.push({  
                                    key: option.ID,  
                                    text: option[results[0].LookupField]  
                                });  
                            }  
                        }  
                        _a.label = 4;  
                    case 4: return [3 /*break*/, 6];  
                    case 5:  
                        error_14 = _a.sent();  
                        return [2 /*return*/, Promise.reject(error_14)];  
                    case 6: return [2 /*return*/, fieldOptions];  
                }  
            });  
        });  
    };  
  

but on runtime the SPFx web part will return this error and it will keep loading forever:-

calendar-web-part_a87ac4ce95dc9057c9f00ccd9727c133.js:1 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'LookupList')    

this is the piece of code which is returning the error:-

return [4 /*yield*/, web.lists.getById(results[0].LookupList)  

as follow:-

any advice on this please?

Answer 1

Hi @john john ,
The LookupList property is undefined because it might doesn't have an initial value. So in your service, try to initialize the LookupList property or confirm the value has pass to the LookupList.

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