1. A computer-implemented method for content sharing in a community space, the method comprising: receiving a first sharing request for the community space from a user; creating the community space in a digital magazine server, the community space comprising a community space identification (ID) and an allocated storage space for the community space in the digital magazine server; generating a community digital magazine for the created community space; receiving one or more content items for the community digital magazine contributed by a plurality of users, wherein each of the plurality of users is a community member of the community digital magazine, and each content item from a community member of the community digital magazine is shared with remaining community members of the community digital magazine; presenting content items contributed by the one or more community members in the community digital magazine; and automatically selecting one or more candidate content items not shared by the community members for the community digital magazine based on the content items previously contributed by the community members, wherein the automatic selection comprises: accessing a machine learning model trained using information about a set of content items including the content items previously contributed by the community members, each content item being associated with a topic, where a label of the machine learning model is whether each content item was added to the community space, and one or more input features of the machine learning model include one or more of: a frequency of sharing of the topic associated with the content item, a number of comments of the topic associated with the content item, and a quality of comments on the topic associated with the content item, identifying the one or more candidate content items that have not been shared by the community members, applying the trained machine learning model to each of the candidate content items, generating a score for each of the identified candidate content items not shared by the community members using the machine learning model, where the score is a prediction of a likelihood of the candidate content item to be selected for the community digital magazine, and selecting the one or more identified candidate content items based on the scores associated with the identified candidate content items; and presenting the selected one or more candidate content items in the community digital magazine to the community members.