Room2.1 DatabaseView あるある

by Koji Wakamiya

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Room2.1 DatabaseView ͋Δ͋Δ ͋Δ͋ΔLTʙ ͓ਖ਼݄ͩΑʂAndroid & iOS߹ಉ େLTେձ ʙ Vol.10

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ࣗݾ঺հ • Koji Wakamiya • Studyplus, inc. • @koji-1009 (Github) • @D_R_1009 (Twitter, Hatena, etc…)

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DatabaseView ࢖ͬͯ·͔͢ʁ

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DatabaseViewʹ͍ͭͯʢ͓͞Β͍ʣ • Room 2.1Ͱ௥Ճ͞Εͨػೳ • Inner/Outer joinΛRoomͰ࣮ݱ • ςʔϒϧΛ͋Δ΂͖ܗʹ෼ׂ͠ දࣔ(View)ʹ߹ΘͤͯσʔλΛ߹੒͢Δ͜ͱ͕Ͱ͖Δ

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ෳ਺ͷςʔϒϧͱForeignKey • ؔ࿈ͷ͋Δෳ਺ͷςʔϒϧΛѻ͏͜ͱʹͳΔͨΊ ForeignKeyΛར༻͢Δ͜ͱ͕͋Δ • ؔ࿈෇͚Λߦ͏͜ͱͰɺத৺ͱͳΔrowΛ࡟আͨ࣌͠ʹ ଞͷςʔϒϧͷrow΋࡟আ͢ΔͳͲͷߟྀΛߦ͏

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OnConﬂictStrategy.REPLACEͰ σʔλ͕ফ͑ͪΌ͏ࣄ݅

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OnConﬂictStrategy • InsetॲཧதʹConﬂict͕ൃੜ(row͕طʹଘࡏ)ͨ࣌͠ ͲͷΑ͏ͳѻ͍Λ͢Δ͔ΛܾΊΔ͜ͱ͕Ͱ͖Δ • DBͷར༻༻్΍໨తʹ߹Θͤͯར༻͢ΔStrategy͕มΘΔ

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OnConflictStrategy • ABORT (default) • OnConflict strategy constant to abort the transaction. • REPLACE • OnConflict strategy constant to replace the old data and continue the transaction. • Ignore • OnConflict strategy constant to ignore the conflict.

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ࣄ݅ঢ়گ • ΞΠςϜςʔϒϧͱΞΠςϜฒͼॱςʔϒϧ͕ଘࡏ • ΞΠςϜ͸ΞϓϦىಈ࣌ʹαʔόʔͱಉظ • @InsertͱOnConﬂictStrategy.REPLACEͰશσʔλߋ৽ • ฒͼॱͷσʔλ͸ΞϓϦ಺ʹ͔͠ଘࡏ͠ͳ͍ͨΊอ࣋

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ࣄ݅ঢ়گ • αʔόʔͱΞϓϦ಺DBΛಉظ(ϦϑϨογϡ)͢Δͱ ΞΠςϜϦετ͕දࣔ͞Εͳ͘ͳΔ • ௐ΂ͯΈΔͱʮΞΠςϜʯͷσʔλ͸͋Δ͕ ʮΞΠςϜฒͼॱʯ͕ଘࡏ͠ͳ͘ͳ͍ͬͯΔ • Inner JoinͷͨΊDatabaseView͕ੜ੒͞Ε͍ͯͳ͍……ʁ

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Ͳ͏ͯ͠σʔλফ͑ͪΌ͏Μ……

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REPLACEʹΑΔUpdateॲཧ • REPLACE͸࣮࣭తʹUpdateॲཧʢͩͱࢥ͍ͬͯͨʣ • Conﬂictൃੜ͠ͳ͍ → ৽نrow࡞੒ॲཧ • Conﬂictൃੜ͢Δ → طଘrowߋ৽ॲཧ

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REPLACEʹΑΔUpdateॲཧ • REPLACE͸࣮࣭తʹUpdateॲཧʢͰ͸ͳ͍ʣ • Conﬂictൃੜ͠ͳ͍ → ৽نrow࡞੒ॲཧ • Conﬂictൃੜ͢Δ → طଘrowߋ৽ॲཧ طଘrow࡟আॲཧ + ৽نrow௥Ճॲཧ

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REPLACEʹΑΔUpdateॲཧ • طଘrowͷ࡟আ + ForeignKeyʹΑΔؔ࿈෇͚ʹΑΓ ʮΞΠςϜʯͷ࡟আͰʮΞΠςϜฒͼॱʯ͕࡟আ͞Ε͍ͯͨ • @InsertͰ͸ͳ͘@UpdateΛར༻͠ͳ͚Ε͹ͳΒͳ͔ͬͨ • ௥Ճͱߋ৽ॲཧΛϝιουͰ੾Γ෼͚Δ͜ͱͰ ͜ͱͳ͖ΛಘΔ͜ͱ͕Ͱ͖ͨ