There is a song called Presque l'amour by Rachid Ferrache. In the song he says:
C'est vrai que j'ai le moral à la rue
What does it really mean to have "le moral à la rue"?
Here are the lyrics to the song.
À la rue (literally: on the street, i.e. out of home, homeless) is here a colloquial idiom meaning "in bad condition, lost".
In the song, the meaning :
It's true, I'm depressed
when I spend two whole days without seeing you
(i.e. I get depressed after two days without seeing you)
A more common expression with the same meaning is avoir le moral à zéro.
One of the reasons why "à la rue" was preferred to "à zéro" is that it rhymes with:
Les copains ça m'intéresse plus
A few words as this question triggered quite a lot of discussions in comments and chats.
This song was aimed at teenagers. It was one of the three Rachid Ferrache's hits in the late eighties. While être à la rue originally meant to be homeless, a new figurative meaning appeared in suburban slang that was "to be lost, to fail miserably" in a context where there is something to achieve, for example at school, at work or while socializing. This new meaning was eventually unrelated to being homeless. You can be both à la rue and at home or at school. Any attempt to link this à la rue and homelessness is missing the point.
Q1: Is j'ai le moral à la rue poetry?
R1: À la rue being technically slang, it's a bit off to say it's poetry.
Q2: Isn't j'ai le moral à la rue actually two expressions?
R2: No, J'ai le moral à la rue is a single expression, a single sentence following the pattern j'ai le moral à/dans/au xxx. It doesn't mean at all j'ai (pas) le moral and je suis à la rue. What is à la rue is not the person but le moral.
Q3: Why didn't the authors of the song didn't use j'ai le moral à zéro which is the canonic form for it?
R3: Because it was already taken! Using it would have been kind of plagiarism. A major French hit named "Ohio" by Serge Gainsbourg, sung by Isabelle Adjani, and released four years earlier had engraved in memories this very sentence so another one had to be found.
Q4: Why should it be considered as an idiom despite not being present elsewhere than in this song?
R4: Because it matches the first definition of idiom found in the Merriam Webster:
an expression in the usage of a language that is peculiar to itself either in having a meaning that cannot be derived from the conjoined meanings of its elements (such as up in the air for "undecided") or in its grammatically atypical use of words (such as give way)
The creative usage of à la rue for a feeling and not a person also makes this sentence an idiom.
Q5: Doesn't the fact no other occurrence seem to exists disqualify this expression to be called an idiom?
R5: Why would it? This song was not a major hit but was likely sung by tens of thousands of teenagers at that time. Let's say it was an ephemeral idiom.
Interestingly, the song Ohio mentioned earlier did definitely create an idiom, and that one was very successful because it is still used almost 40 years later. The idiom is Je suis dans un état proche de l'Ohio and is understood to mean "I'm lost, I'm exhausted".
avoir ou ne pas avoir le moral:
to feel good, to be in good spirits, to be happy versus to not feel good, be in poor spirits, to be down or sad
être à la rue: to be homeless, also in English could be: down and out. If you are homeless, it's usually depressing and we often say for that: to be down and out.
It is in several dictionaries:
Subir un échec cuisant. Origine
Se dit d'une personne qui vient de connaître une situation si difficile qu'elle ne peut envisager d'avenir plus positif [to be down and out]. Peut aussi, plus rarement, désigner le fait d'être en retard. Plus généralement, cette expression est employée quand quelqu'un ne sait pas où dormir et cherche une solution d'hébergement provisoire.
[Please note: not depressed]
So, poetically speaking: I feel down and out.
C'est vrai is, of course, it's true.
You could say homeless too: I feel homeless.
All songs use poetry. This is a general statement.