Does John 15:7 promise that God will give me whatever I ask?

Most misuse of this verse comes from quoting the second half without the first. Jesus does not say ask what you will and it shall be done. He says if you remain in me, and if my words remain in you, then ask. The promise is genuine, and it is spoken to disciples whose desires are being formed by His speech.

This is not a loophole that empties the promise. It is a description of how prayer works in a real relationship. A person soaked in Christ's words gradually stops asking for things Christ never wanted, and starts asking for things He has already said He intends to do.

Verse 8 tells you what the Father is glorified by: much fruit. Verse 16 says the disciples were ordained to fruit that remains, and then attaches the promise of asking. Put those together and the prayers in view are prayers for a fruitful, obedient, loving life and for the work of witness that follows, not prayers for a life free of difficulty. Verse 18 onward makes clear how much difficulty is coming.

In His name, verse 16, is not a formula appended to a request. It means asking as His representative, for His purposes, on the strength of who He is. A messenger asking in a king's name asks for what the king sent him to accomplish.

Scripture is not embarrassed by unanswered prayer. James 4:3 says people ask and do not receive because they ask amiss, to spend on their own pleasures. Paul asked three times for a thorn to be removed and was told no, and given something else instead: my grace is sufficient for you. Jesus Himself prayed in Gethsemane, if it be possible, let this cup pass from me, and then, not as I will, but as you will.

So the pattern of confident asking in John 15 runs alongside the pattern of submitted asking in Gethsemane, and they are the same person's teaching. A believer may ask boldly precisely because the Father can be trusted to answer wisely.