使用CloudKit的NSPredicate和BEGINSWITH：字段值类型不匹配

Question

I have a table "Store" with the attributes "name" of type String (indexes checked for sort query and search). I want to execute a SQL like query to find all stores with name beginning with a substring.

So I tried this predicate :

NSPredicate *pred = [NSPredicate predicateWithFormat:@"ANY name BEGINSWITH %@",substring];

CKQuery *query = [[CKQuery alloc]initWithRecordType:@"Store" predicate:pred];

CKQueryOperation *queryOperation = [[CKQueryOperation alloc] initWithQuery:query];

queryOperation.desiredKeys = @[@"name",@"category"];

NSMutableArray *results = [[NSMutableArray alloc] init];

queryOperation.recordFetchedBlock = ^(CKRecord *record) {
    [results addObject:record];
};
queryOperation.queryCompletionBlock = ^(CKQueryCursor *cursor, NSError *error) {
   //my own code
}
[publicDatabase addOperation:queryOperation];

I have this error :

<CKError 0x1887a540: "Invalid Arguments" (12/1009); "Field value type mismatch in query predicate for field 'name'"> for query : <CKQuery: 0x18882650; recordType=Store, predicate=ANY name BEGINSWITH "mysubstring">

Answer 1

Wild guess...try:

[NSPredicate predicateWithFormat:@"ANY {'name','category'} BEGINSWITH %@",substring]; 

That may be an incorrect reversal of key/value but it might work.

Answer 2

A completely different approach would be to create a third field called "nameAndCategory", append the two strings and add them to the field. Then figure out how to do the full text search (tokenized string search) with the predicate:

[NSPredicate predicateWithFormat:@"self contains '%@'",substring]; 

or

[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"self contains '%@'",substring];

But perhaps the only sure approach is to do two searches and combine the results.

Answer 3

My guess is that you need to get rid of the "ANY".

The ANY and SOME aggregate operators may be combined with the IN and CONTAINS operators to perform list membership tests.

So ANY is for lists (Arrays). Since 'name' is a String, it is not a list, hence the mismatch error: "Field value type mismatch in query predicate for field 'name'"