Re: [webdatabase] Handling of the query arguments
On Thu, 19 Nov 2009, Maciej Stachowiak wrote: ECMAScript defines a ToPrimitive conversion (Section 9.1 of ECMA-262 5th edition). I think the right thing to do would be for some spec to point to those steps. Probably it has to be Web Database, because in many cases where a Web IDL method takes an any type, it's not appropriate to do ToPrimitive conversion. So required. -- Ian Hickson U+1047E)\._.,--,'``.fL http://ln.hixie.ch/ U+263A/, _.. \ _\ ;`._ ,. Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
[webdatabase] Handling of the query arguments
Hi everyone. Neither the web database specification, nor the IDL, specify the fine grained handling that implementation must do of the several possible values that can be passed in the 2nd argument to executeSql, considering that those ecmascript values need to be handled by the SQL engine, and therefore converted into a database compatible value. The only reference to the arguments is the paragraph that tell that the arguments should be replaced, but I've already asked that paragraph language to be reviewed in http://lists.w3.org/Archives/Public/public-webapps/2009JulSep/1329.html Handling of ecmascript to database types could be done the following way: - numerical values would be converted to REAL - strings would be converted to TEXT, including the empty string - booleans would be converted to lowercase TEXT false or true - null and undefined would be handled as NULL - functions would be converted to TEXT Objects, which do not fit the primitive types about, can be handled in two ways. 1) The quick cheap way, which was already hinted, would be to convert them to string. However, that's not very helpful, if the object is a native type wrapper like: new String(aa); new Number(1); new Boolean(true) 2) We can define, in the Web IDL, how an object can be converted to a primitive type. Specifically, in an ecmascript binding we can do the following (note: returns means to stop the steps): - if object is null, return null - if object has a member function called valueOf, invoke valueOf in the context of object - if the returned value is a primitive type, return the value, - if object has a member function called toString, invoke toString in the context of object - if the returned value is a primitive type, return the value, - return Object.prototype.toString.call(object), so we get [object Class] The returned primitive type would then go through the ecmascript to database type steps above. However, the Web IDL need to be language agnostic, so I'll leave for the Web IDL maintainers to decide if this is of its scope and specifiable. There might need to be clarification on how to define what is a numerical value, a string, a boolean, null and undefined, and functions. We could say that a numerical value is just a number, but ideally, it should also include Number() instances, despite these could return non numerical values from their valueOf, but then we would go into the object-to-primitive steps. The complete, we need the specification to tell how to convert database types back into ecmascript object, but this is easier: - TEXT, and other text types are converted to DOMString - REAL and other number types are converted to double - NULL is converted to null - DATE/TIMESTAMP types should be converted to Date objects, if supported Thank you for your time. -- João Eiras Core Developer, Opera Software ASA, http://www.opera.com/
Re: [webdatabase] Handling of the query arguments
On Nov 19, 2009, at 2:12 PM, João Eiras wrote: Hi everyone. Neither the web database specification, nor the IDL, specify the fine grained handling that implementation must do of the several possible values that can be passed in the 2nd argument to executeSql, considering that those ecmascript values need to be handled by the SQL engine, and therefore converted into a database compatible value. The only reference to the arguments is the paragraph that tell that the arguments should be replaced, but I've already asked that paragraph language to be reviewed in http://lists.w3.org/Archives/Public/public-webapps/2009JulSep/ 1329.html Handling of ecmascript to database types could be done the following way: - numerical values would be converted to REAL - strings would be converted to TEXT, including the empty string - booleans would be converted to lowercase TEXT false or true - null and undefined would be handled as NULL - functions would be converted to TEXT Objects, which do not fit the primitive types about, can be handled in two ways. 1) The quick cheap way, which was already hinted, would be to convert them to string. However, that's not very helpful, if the object is a native type wrapper like: new String(aa); new Number(1); new Boolean(true) 2) We can define, in the Web IDL, how an object can be converted to a primitive type. Specifically, in an ecmascript binding we can do the following (note: returns means to stop the steps): - if object is null, return null - if object has a member function called valueOf, invoke valueOf in the context of object - if the returned value is a primitive type, return the value, - if object has a member function called toString, invoke toString in the context of object - if the returned value is a primitive type, return the value, - return Object.prototype.toString.call(object), so we get [object Class] ECMAScript defines a ToPrimitive conversion (Section 9.1 of ECMA-262 5th edition). I think the right thing to do would be for some spec to point to those steps. Probably it has to be Web Database, because in many cases where a Web IDL method takes an any type, it's not appropriate to do ToPrimitive conversion. Regards, Maciej
Re: [webdatabase] Handling of the query arguments
2) We can define, in the Web IDL, how an object can be converted to a primitive type. Specifically, in an ecmascript binding we can do the following (note: returns means to stop the steps): - if object is null, return null - if object has a member function called valueOf, invoke valueOf in the context of object - if the returned value is a primitive type, return the value, - if object has a member function called toString, invoke toString in the context of object - if the returned value is a primitive type, return the value, - return Object.prototype.toString.call(object), so we get [object Class] ECMAScript defines a ToPrimitive conversion (Section 9.1 of ECMA-262 5th edition). I think the right thing to do would be for some spec to point to those steps. Probably it has to be Web Database, because in many cases where a Web IDL method takes an any type, it's not appropriate to do ToPrimitive conversion. Indeed ! -- João Eiras Core Developer, Opera Software ASA, http://www.opera.com/
